m/s big buoy

M/S BIG BUOYSpecialised Cargo Vessel for Waves4Power ABMarine Design Project 2017

Naval Architecture and Ocean Engineering International Master Programme

Department of Mechanics and Maritime SciencesCHALMERS UNIVERSITY OF TECHNOLOGYGothenburg, Sweden 2017


Aristomenis ChidiroglouErik LengyelGabor GulyasJillian AdamsPaulo MacedoTor-Håkon StrömsengVinayak ShuklaWael Al HajiYangfan Li


Department of Mechanics and Maritime SciencesChalmers University of TechnologySE-412 96 Göteborg SwedenTelephone +46(0)31-772 1000Printed by Chalmers ReproserviceGothenburg, Sweden, 2017

Abstract

The M/S Big Buoy is a specialised cargo vessel intended to carry and install wave energyconverter buoys from Norway to offshore farms in the North Sea. The ship has beendesigned according to DNV-GL classification rukes as a 1A Specialised Cargo ship. Ithas the capacity to transport 25 buoys at a time by utilising its three cargo holds. Thebuoys are supported by specialised frames designed to be moved with translifters to theirstorage locations. The cargo holds are linked with an elevator that services two decksat a time. Finally, the buoys are brought onto the ship directly from the water with aunique stern ramp.Beginning with a conventional open bow shape and followed by investigations of bulbousbow performance and different bow concepts, the final hull of the ship is inspired by theULSTEIN X-BOW®. The closed concave bow is proven to provide better seakeepingproperties which, due to the installation operation, was the principal focus of hydrody-namic optimisation of this project. The wave making resistance was minimised throughsystematic evaluation of parameter variations of the parametrically designed hull model.The vessel complies with intact and damage stability IMO and SOLAS criteria. Theseare directly connected to the vessel design. The M/S Big Buoy is equipped with dynamicpositioning and designed to be able to maintain its position during the installation ofbuoys in sea waves up to a significant height of 3 m. Different sized propellers wereevaluated, in conjunction with the ship to ensure the highest cost-benefit is achieved.The structural design of the vessel concentrates on the parallel midbody of the ship,being the most challenging part of the design due to the lack of bulkheads and pillars.The side and bottom structures are primarily governed by the internal pressures in theballast tanks. The deck structures are dimensioned to accommodate higher loads thaninduced by the buoys to ensure flexibility in the cargo carrying capacity. The structuresare selected to be as lightweight as possible while still meeting the rule requirements.Equipped with two Wärtsilä 10V31D main engines and two 6L20D auxiliary engines, theM/S Big Buoy is capable of generating a total 13.5 MW of power. The primary fuelsource is methanol. The ship is also equipped with batteries and an efficient waste heatrecovery system to increase the energy efficiency of the ship.In addition to carrying wave energy converter buoys, the M/S Big Buoy can serve asa traditional RORO vessel in the future. The large, open cargo decks allow for a vari-ety of cargoes to be carried with minimal changes to the hull structures or the vessel’sarrangement.

Keywords: wave buoy, cargo ship, North Sea, safety, offshore, seakeeping performance,FEM, clean technology, methanol, RORO

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Preface and Acknowledgement

The Marine Design Project, MMA 151, is a mandatory 15 credit course within the Mas-ter’s program of Naval Architecture and Ocean Engineering at Chalmers University ofTechnology. The course is organised by the department of Mechanics and Maritime Sci-ences.The objective is to develop a conceptual design of a vessel to transport and install waveenergy converter buoys designed by Waves4Power.The project members would like thank and acknowledge the help and support of thefollowing:

To Bengt Ramne, Per Hogström, Fabian Tillig and Anders Ulfvarson, thank youfor the guidance, knowledge and patience throughout the duration of the project.To Bengt Mårlind and Tore Mårlind, thank you for providing us the opportunityto work on such a unique design.To our classmates, thank you for listening to our ideas and providing company andemotional support throughout the project.To Chalmers University of Technology, thank you for Ritsalen; this project wouldhave been significantly more difficult without a place to call home.To all the software developers, thank you for streamlining the process of transferringfiles between programs.To Föreningen Chalmers Skeppsbyggare, thank you for keeping the kitchen alwaysstocked and the prices always low.

Project Members

General Arrangement Erik LengyelJillian Adams

Hydrodynamics Paulo MacedoTor-Håkon Strömseng

Structure Aristomenis ChidiroglouYangfan Li

Machinery Gabor GulyasVinayak Shukla

Wael Al Haji

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Executive Summary

The following section is a brief outline of the work accomplished. The mission profile,the main particulars and a general overview of the vessel are presented in this section.

Mission Profile

The aim of the project is to design a specialised cargo ship to transport wave energyconverter buoys designed by Waves4Power. The ship should be able to transport andinstall 1000 buoys each year between the production site and the offshore wave energyfarm. Sustainability and safety of the crew are two of the most important factors in thedesign of the ship. The general arrangement of the M/S Big Buoy is shown in AppendixB.

Main Particulars

Type Specialised Cargo ShipFlag NorwegianClass DNV-GL 1A

Battery (Safety)E0DYNPOS (AUT)Clean (Tier III)COMF (V-crn)

Dimensions Length overall, LOA 197.6 mRule length, LPP 197.6 mBeam moulded, B 32 mDraft, T 5 mDepth, D 22.5 mDesign Speed, VD 15 knotsFrame Spacing 800 mmDisplacement, ∆ 19 828 tLightship Weight, WLS 12 542 tMethanol Capacity 2750 m3

Main Engine Wärtsilä 10V31D 11.3 MWAuxiliary Engine Wärtsilä 6L20D 2.2 MWPropulsion 2 x Azipod CO1400 FPP

Diameter, DP 3.5 mNo. Blades, Z 5

Accommodations Cabins 24

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Executive Summary

Figure I: Main profiles of the M/S Big Buoy

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Executive Summary

General Overview

The M/S Big Buoy is a specialised cargo vessel designed to carry wave energy converterbuoys designed by Waves4Power. The aim of the design project is to develop a concep-tual design that could transport and install 1000 buoys per year. The primary area ofoperation of the M/S Big Buoy is the North Sea since it will transport the buoys fromthe west coast of Norway to the north-western coast of Ireland. For the ship to be afeasible investment, it must carry 25 buoys per round trip. The outboard and centerlineprofiles of the M/S Big Buoy are presented in Figure I.The arrangement of the M/S Big Buoy is governed by the large volume occupied by the25 buoys it must carry. Three cargo holds are located in the midbody and stern of theship. The lower hold, contained within the watertight portion of the hull, holds 5 buoys.The main cargo hold, located on the main deck 12.5 m above the baseline, holds 11buoys and serves as the centre of the cargo handling operations. The upper cargo hold,found on the weather deck, houses 9 buoys and the control stations for the installationand recovery operations. The cargo holds are all connected through a specialised cargoelevator specifically designed to fit the buoys. To deploy buoys from the ship and recoverbuoys from the water, a stern ramp is installed on the starboard side. The stern rampis rather unconventional, since it must be able to rotate 180◦ to place the buoys in thevertical position in the water. Additionally, two platforms are incorporated into the rampto give access for the installation crews to the head of the buoy.The hull of the ship is inspired by the ULSTEIN X-BOW®. Compared to a conventionalhull, the closed concave bow hull is superior in its seakeeping ability, a crucial charac-teristic for the intended operation in the North Sea. Additionally, the ship passes allrelevant intact and damage stability criteria. Two 3.5 m diameter propellers are installedto provide the thrust necessary to overcome the hull’s resistance of 366.1 kN in calmwater.The structures of the M/S Big Buoy are carefully designed to accommodate the large,continuous cargo holds. The ship is longitudinally framed with a frame spacing of 800mm. A 4 m double hull is found throughout the majority of the ship to create a strongstructural foundation. The primary loads that govern the structural design are the wave-induced pressure, internal pressure in the ballast tanks and cargo loads.The machinery systems on the ship are designed to minimise the impact on the envi-ronment. Methanol is used to generate power through the two Wärtsilä 10V31D mainengines and two Wärtsilä 6L20D auxiliary engines. These engines supply a total of 13.5MW of energy to be distributed to the propulsion system, the hotel load and the cargohandling system. In addition to the engines, batteries have been installed to reduce thepeaks experienced by the engines and allow them to operate more efficiently.

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Executive Summary

ix

ContentsAbstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iiiPreface and Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . . . . vExecutive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viContents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xList of Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiiList of Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xivList of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviiiList of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxii

1 Introduction 11.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Project Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Design Basis 52.1 Ship Mission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.2 Stakeholders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.3 Special Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.4 Rules and Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3 Logistics and Operation 73.1 Cargo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.2 Instalment Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.3 Transit Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.4 Operational Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 103.5 Cost Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4 General Arrangement 154.1 Main Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.2 Cargo Holds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.3 Superstructure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194.4 Anchoring and Mooring . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.5 Safety Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234.6 Weight Estimate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264.7 Other Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

5 Hydrodynamics 315.1 Main Particulars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315.2 Lines Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325.3 Stability Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355.4 Hull Concepts Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . 395.5 Seakeeping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445.6 Resistance Estimations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 505.7 Propeller Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

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Contents

6 Structure 596.1 Design Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 596.2 Midship Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 616.3 Buckling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 696.4 Finite Element (FE) Analysis . . . . . . . . . . . . . . . . . . . . . . . . 71

7 Machinery 857.1 Rules and Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 857.2 Comparison of Fuel Types . . . . . . . . . . . . . . . . . . . . . . . . . . 877.3 Feasibility of Different Fuel Systems . . . . . . . . . . . . . . . . . . . . . 897.4 Engine Load Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . 937.5 Power Plant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 957.6 Propulsors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1047.7 Exhaust System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1057.8 Waste Heat Recovery Unit (WHRU) . . . . . . . . . . . . . . . . . . . . 1077.9 Fuel System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1157.10 Ventilation System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1167.11 Water Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1177.12 Anchoring and Mooring Equipment . . . . . . . . . . . . . . . . . . . . . 1237.13 Optimisation of Power Plant . . . . . . . . . . . . . . . . . . . . . . . . . 1237.14 Energy Efficiency Design Index . . . . . . . . . . . . . . . . . . . . . . . 125

8 Alternative RORO Operations 1298.1 General Arrangement Considerations . . . . . . . . . . . . . . . . . . . . 1298.2 Structural Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . 1298.3 Propulsion Estimations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1298.4 Intact Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1318.5 Damage Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

9 Future Work 1339.1 General Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1339.2 Hydrodynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1339.3 Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1349.4 Machinery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

References 137

Appendix A - Tables I

Appendix B - Drawings VII

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List of Abbreviations

Abbreviation – Description

AE – Auxiliary EngineAP – Aft PerpendicularCFD – Computational Fluid DynamicsCO2 – Carbon DioxideDNV-GL – Det Norske Veritas - Germanischer LloydDP – Dynamic PositioningEAR – Expanded Blade Area RatioECA – Emission Control AreasEE – Energy EfficiencyEEDI – Energy Efficiency Design IndexEGCS – Exhaust Gas Cleaning SystemEGR – Exhaust Gas Re-CirculationFE – Finite ElementFOB – Flat of BottomFOS – Flat of SideFP – Forward PerpendicularFPP – Fixed-Pitch PropellerGM – Metacentric HeightGMT – Transverse Metacentric HeightGT – Gross TonnageGZ – Righting ArmHFO – Heavy Fuel OilHVO – Hydro-treated Vegetable OilIACS – International Association of Classification SocietiesILO – International Labour OrganisationIMO – International Maritime OrganisationITTC-78 – 1978 International Towing Tank ConferenceJONSWAP – Joint North Sea Wave Observation ProjectKB – Centre of BuoyancyKG – Centre of GravityLBG – Liquefied Bio GasLCG – Longitudinal Centre of GravityLHV – Lower Heating ValueLNG – Liquefied Natural Gas

MARPOL – International Convention for the Prevention of Pollutionfrom Ships

MCR – Maximum Continuous RatingMDO – Marine Diesel OilME – Main Engine

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List of Abbreviations

Abbreviation – Description

MGO – Marine Gas OilMSI – Motion Sickness IndexNECA – NOx Emission Control AreaNOX – Nitrous OxidesOCIMF – Oil Companies International Marine ForumORC – Organic Rankin CyclePNA – Principles of Naval ArchitectureRANS – Reynolds-averaged Navier-StokesRMS – Root Mean SquareRORO – Roll On, Roll Offrpm – Rotations per MinuteSCR – Selective Catalytic ReductionSECA – Sulphur Emission Control AreaSFOC – Specific Fuel Oil ConsumptionSOX – Sulphur OxidesSOLAS – Safety of Life at SeaTCG – Transverse Centre of GravityTRO – Total Residual OxidantVCG – Vertical Centre of GravityVLCC – Very Large Crud CarriersWEC – Wave Energy ConverterWHRU – Waste Heat Recovery Unit

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List of Variables

Variable [Unit] Description

∆ m3 Displacement∆TP K Change in Temperatureη0 % Propeller EfficiencyηH % Hull Efficiencyηpump % Pump Efficiencyηtb % Turbine Efficiencyλy - Yield Utilisation Factorλyperm - Permissible Yield Utilisation Factorν - Poisson Ratioσc MPa Critical Buckling StressσE MPa Euler Buckling Stressσy MPa Yield Stressφdq J Heat Emission from Main Engineφdg J Heat Emission from Auxiliary Engineφb J Heat Emission from Boilersφp J Heat Emission from Steam and Condensate Pipes

φg J Heat Emission from Electric Air-CooledGenerators

φep J Heat Emission from Exhaust PipesAd m2 Cross Section Area for Ventilation DuctsAl m2 Cross Section Area for Plate and StiffenerB m Beam or Breadthb m Span of Entire PlateCF - Frictional Resistance CoefficientCFAE gCO2/gFuel Carbon Factor for Fuel for Auxiliary EnginesCFME gCO2/gFuel Carbon Factor for Fuel for Main EnginesCB - Block CoefficientCP - Prismatic CoefficientCPV - Viscous Pressure Resistance CoefficientCW - Waterplane CoefficientCWTWC - Wave Resistance Coefficientc - Heat Transfer CoefficientD m Moulded DepthDP m Propeller Diameter

ds m Larger Distance to The Neutral Axis for TheAssembly of Plate and Stiffener

dz m Distance to the Midship Neutral AxisE GPa Young’s ModulusEAR % Expanded Area Ratio

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List of Variables


EN - Equipment NumberFn - Froude Number

feff - Correction Factor for Availability of InnovativeTechnologies

fc -Correction Factor for Capacity of Ships withAlternative Cargo Types that Impact theDeadweight-Capacity Relationship

fi -Correction Factor for Capacity of Ships withTechnical/Regulatory Elements that influenceShip Capacity

fj - Correction Factor for Ship Specific DesignFeatures

fw - Correction Factor for Speed Reduction due toRepresentative Sea Conditions

H m Height from Summer Load Waterline to the Topof the Uppermost Deck

HDB m Double Bottom HeightHS m Significant Wave HeightHDB m Double Bottom Heighth kJ/kg Enthalpyhi m Web Heighthw m Web HeightIa m4 Longitudinal Moment of InertiaIb m4 Transverse Moment of InertiaIb,req m4 Required Transverse Moment of Inertia

Imid m4 Total Midship Moment of Inertia from NauticusHull

Ip m4 Moment of Inertia of Plate

Is m4 Moment of Inertia for The Assembly of Plate andStiffener

J - Advance Coefficientk - Form FactorKQ - Torque CoefficientKTT - Thrust Coefficientk - Material FactorLCF m Longitudinal Centre FlotationLCG m Longitudinal Centre of GravityLFE m Length of the FE modelLOA m Length Over AllLPP m Length Between PerpendicularsLWL m Length of WaterlineLex m Length of Exhaust DuctLin m Length of Air Intake Ductlf m Flange Lengthls m Distance Between Two Longitudinal Stiffenerslp - Unit Length

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List of Variables


Mmax Nm Maximum Bending MomentMmaxsection

Nm Sectional Maximum Bending MomentMhog Nm Bending Moment from Nauticus HullmR113 kg/s.m2 Mass Flux of R113mR245 kg/s.m2 Mass Flux of R245neff - Number of Innovative TechnologiesnME - Number of Main EnginesnPTI - Number of Power Take-In SystemsP MPa Pressure

PAE kW Ship Auxiliary Power Requirements at NormalSea Going Conditions

PAEeff kWAuxiliary Power Reduction due to use ofInnovative Electric Power GenerationTechnologies

PD W Delivered PowerPE W Effective PowerPD - Blade Pitch–Ratio

PME kW Ship propulsion Power that is 75% of Main engineMaximum Continuous Rating or Shaft Motor

PPTI kW 75% of Installed Power for Each Power Take-InSystem

Peff kW 75% of Installed Power for Each InnovativeTechnology that Contributes to Ship Propulsion

Pex kN/m2 Pressure from Nauticus HullQ N Equivalent Total ForceQA m3 Total Airflowqb m3 Airflow for Boilersqc m3 Airflow for Combustionqh m3 Airflow for Heat Evacuationqdp m3 Airflow for Combustion in Main Enginesqdg m3 Airflow for Combustion in Auxiliary EnginesR m Bilge RadiusRW N Wave making resistanceRT N Towing Resistance

SFCAE g/kWh Specific Fuel consumption for Auxiliary Enginesas per NOx Certification Values

SFCME g/kWh Specific Fuel consumption for Main Engines asper NOx Certification Values

Sh kJ/kg.K EntropySref - Wetted Surface CoefficientSf m Frame SpacingT m Design DraftTP K TemperatureTp s Peak PeriodTz s Zero-Up Crossing Periodtb m Curved Bilge Thickness

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List of Variables


tf m Flange Thicknesstfloor m Floor Thicknesstp m Plate Thicknesstw m Web ThicknessWLS t Lightship WeightWnet kJ Net WorkWtb kJ Work of PumpWpump kJ Work of Turbinew N/m2 Pressure LoadVA m/s Air VelocityVC m/s Current SpeedVD kn Design Speed

Vref kn Reference Ship Speed Attained at PropulsionPower Equal to PME

Z - Number of Propeller BladesZn m Midship Neutral Axis from Base LineZp m Distance to The Neutral AxisZrequired m3 Required Section Modulus

xvii

List of Figures

I Main profiles of the M/S Big Buoy . . . . . . . . . . . . . . . . . . . . . vii

1.1 General ship design spiral (Vossen, Kleppe, & Hjørungnes, 2013) . . . . . 2

2.1 Ship’s stakeholders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.1 Main dimensions of the Waves4Power WEC buoys . . . . . . . . . . . . 73.2 Sample drawing of the installation array . . . . . . . . . . . . . . . . . . 83.3 Approximate route between production facilities and installation site . . 93.4 Buoy recovery operations . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.5 On-board cargo movements from ramp to elevator . . . . . . . . . . . . . 123.6 Crew hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.7 Cost estimation for the M/S Big Buoy . . . . . . . . . . . . . . . . . . . 14

4.1 Centerline profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.2 Cargo hold layouts of the M/S Big Buoy . . . . . . . . . . . . . . . . . . 164.3 Cargo elevator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.4 Stern ramp design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184.5 Translifter (TTS Port Equipment AB, 2017b) . . . . . . . . . . . . . . . 194.6 Support frame for buoys . . . . . . . . . . . . . . . . . . . . . . . . . . . 194.7 Deck 6 and 7 layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.8 Cabin layouts on-board the M/S Big Buoy . . . . . . . . . . . . . . . . . 224.9 Aft mooring gear arrangement . . . . . . . . . . . . . . . . . . . . . . . . 234.10 Weight breakdown by component . . . . . . . . . . . . . . . . . . . . . . 274.11 Tank distribution throughout the hull . . . . . . . . . . . . . . . . . . . . 28

5.1 Final buttocks and waterlines . . . . . . . . . . . . . . . . . . . . . . . . 335.2 Final body plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345.3 Isometric view of the final hull . . . . . . . . . . . . . . . . . . . . . . . . 345.4 Maximum KG curve (left) and minimum GM curve (right) . . . . . . . . 365.5 GZ-curve for the different loadcases . . . . . . . . . . . . . . . . . . . . . 375.6 Zone division of the vessel . . . . . . . . . . . . . . . . . . . . . . . . . . 385.7 Floodable length of the vessel . . . . . . . . . . . . . . . . . . . . . . . . 395.8 Wave pattern and pressure distribution for hull with bulbous bow (upper)

and without a bulbous bow (lower) . . . . . . . . . . . . . . . . . . . . . 405.9 Wave pattern and pressure distribution for the baseline hull (upper) and

the optimised (lower) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425.10 Hull forebody shape, conventional open bow (left) and closed bow (right),

3D detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425.11 Hull forebody lines, conventional open bow (blue) and closed bow (red) . 435.12 MSI performance for the final hull for Tz = 6.5 s (upper left), Tz = 7.5 s

(upper right), Tz = 8.5 s (lower left) and Tz = 9.5 s (lower right) . . . . . 465.13 Vertical accelerations in a sea state with Hs = 2 m and Tz = 8.5 s (initial

to left and final to the right) . . . . . . . . . . . . . . . . . . . . . . . . . 47

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List of Figures

5.14 Roll motion comparison for the different hulls (initial to left and final tothe right) concepts in a sea state with Hs = 3 m and Tz = 8.5 s. . . . . . 47

5.15 DP capability plot accordingly to heading angle and wind speed . . . . . 495.16 Estimated towing resistance . . . . . . . . . . . . . . . . . . . . . . . . . 505.17 Final hull complete CFD simulation . . . . . . . . . . . . . . . . . . . . . 525.18 Added wave resistance for the closed bow (left) and open bow (right) . . 535.19 The final hull sailing at 15 knots in sea state 5 (7 m wave height and 9.5

wave period) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535.20 Pressure distribution on the blade area . . . . . . . . . . . . . . . . . . . 555.21 Wake fraction disc for 3.50, 3.75 and 4.00 m propeller diameter . . . . . . 565.22 Propeller emergence comparison between 3.5 m diameter (left side) and 4

m diameter (right side) in a sea state of Hs = 1.5 m and Tz = 6 seconds . 575.23 Open water diagram for the final chosen propeller . . . . . . . . . . . . . 575.24 Final propeller 3D visualisation . . . . . . . . . . . . . . . . . . . . . . . 58

6.1 Loads, shear forces and moments acting on the hull in still water, loadcase A 606.2 Loads, shear forces and moments acting on the hull in still water, loadcase B 606.3 Pressure Distribution at the midship Section . . . . . . . . . . . . . . . . 616.4 Longitudinal stiffener properties . . . . . . . . . . . . . . . . . . . . . . . 646.5 Web frames properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . 676.6 Midship section of port side . . . . . . . . . . . . . . . . . . . . . . . . . 686.7 Longitudinally Stiffened Plate . . . . . . . . . . . . . . . . . . . . . . . . 696.8 Ship’s part under FE analysis . . . . . . . . . . . . . . . . . . . . . . . . 726.9 View of the FE model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 736.10 Supports used in FE analysis . . . . . . . . . . . . . . . . . . . . . . . . 736.11 The meshed model used for the FE analysis (zoom) . . . . . . . . . . . . 756.12 The BSR-1P dynamic loadcase acting on the ship’s hull . . . . . . . . . . 766.13 30x exaggerated global deformation for loadcase A . . . . . . . . . . . . . 776.14 30x exaggerated global deformation for loadcase B . . . . . . . . . . . . . 776.15 The von Mises stress plot for the outer bottom plate for loadcase A (upper)

and loadcase B (upper) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 796.16 The von Mises stress plot for the inner bottom plate for loadcase A (upper)

and loadcase B (upper) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 806.17 The von Mises stress plot for the outer side wall for loadcase A (upper)

and loadcase B (lower) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 816.18 The von Mises stress plot for the inner side wall for loadcase A (upper)

and loadcase B (lower) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 826.19 The von Mises stress plot for the main deck for loadcase A (upper) and

loadcase B (upper) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 836.20 The von Mises stress plot for the weather deck for loadcase A (upper) and

loadcase B (upper) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

7.1 Estimated ECA in future (GREEN4SEA, 2017) . . . . . . . . . . . . . . 867.2 Comparison of Marine Fuel Prices (Ellis, 2017). . . . . . . . . . . . . . . 907.3 Methanol Fuel System (DNV-GL, 2016a) . . . . . . . . . . . . . . . . . . 927.4 Energy balance consideration (ABB, 2017) . . . . . . . . . . . . . . . . . 947.5 Operational profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 947.6 Electrical Transmission Heat Loss (MAN, 2015a) . . . . . . . . . . . . . 957.7 Methanol-electric system arrangement (ABB, 2009) . . . . . . . . . . . . 96

xix

List of Figures

7.8 Retrofitted common rail system for methanol (Stojcevski, 2015) . . . . . 977.9 Retrofit Solution on Engine Piping (Stojcevski, 2015) . . . . . . . . . . . 977.10 Power range for Wärtsilä HY2 (Wärtsilä, 2017f) . . . . . . . . . . . . . . 1007.11 Diesel-Electrical Hybrid System (Wärtsilä, 2017f) . . . . . . . . . . . . . 1017.12 Machinery layout on Deck 1 . . . . . . . . . . . . . . . . . . . . . . . . . 1027.13 Machinery layout on Deck 2 . . . . . . . . . . . . . . . . . . . . . . . . . 1037.14 Different model units, power vs. propeller speed (ABB, 2015) . . . . . . 1047.15 Tunnel Thruster (Sinha, 2017) . . . . . . . . . . . . . . . . . . . . . . . . 1057.16 Compact catalyst layers reactor with integrated silencer (Wärtsilä, 2015) 1067.17 WHRS Configuration (MAN, 2015b) . . . . . . . . . . . . . . . . . . . . 1087.18 Multiple Economisers for maximum efficiency . . . . . . . . . . . . . . . 1097.19 Stand Alone Power Turbine System (MAN, 2015b) . . . . . . . . . . . . 1097.20 2 phased Steam and Power turbine system for maximum efficiency . . . . 1107.21 Schematic layout of ORC . . . . . . . . . . . . . . . . . . . . . . . . . . . 1117.22 T-S diagram of R113 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1137.23 T-S diagram of R245fa . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1147.24 Line drawing for Diesel-Methanol fuel system . . . . . . . . . . . . . . . 1157.25 Designed ventilation tunnels . . . . . . . . . . . . . . . . . . . . . . . . . 1167.26 Working principle of the fresh water generator System (Wärtsilä, 2017b) 1187.27 ACO Maripur NF Membrane Bio Reactor (ACO Marine, 2017d) . . . . . 1197.28 ACO Clarimar MF Biological Sewage Treatment System (ACO Marine,

2017c) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207.29 Overview of Sewage Treatment System . . . . . . . . . . . . . . . . . . . 1207.30 Line diagram of Central Cooling system . . . . . . . . . . . . . . . . . . 1217.31 Line diagram of Ballast Water Treatment . . . . . . . . . . . . . . . . . . 1227.32 EEDI reference curve for bulk carriers (IMO, 2016) . . . . . . . . . . . . 126

8.1 GZ-curve for the RORO fully loaded departure loadcase . . . . . . . . . . 132

xx

List of Tables

3.1 Transit study optimisation . . . . . . . . . . . . . . . . . . . . . . . . . . 93.2 Limiting wave heights for operations . . . . . . . . . . . . . . . . . . . . 133.3 Cost estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.1 Preliminary displacement estimate . . . . . . . . . . . . . . . . . . . . . 264.2 Preliminary steel weight estimate . . . . . . . . . . . . . . . . . . . . . . 274.3 Summary of tank volumes . . . . . . . . . . . . . . . . . . . . . . . . . . 28

5.1 Main hydrodynamics particulars . . . . . . . . . . . . . . . . . . . . . . . 325.2 Load cases evaluated for intact stability . . . . . . . . . . . . . . . . . . 355.3 Hydrostatic data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365.4 Damage stability results . . . . . . . . . . . . . . . . . . . . . . . . . . . 385.5 Resistance comparison with and without bulbous bow . . . . . . . . . . . 405.6 Resistance comparison of the baseline and optimised hull without bulbous

bow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415.7 General seakeeping results (final hull) and operational criteria . . . . . . 455.8 Comparison of seakeeping characteristics between initial and final design 455.9 Correlation of wave height, crossing period and wind speed (The Interna-

tional Marine Contractors Association, 2000) . . . . . . . . . . . . . . . . 495.10 CFD resistance estimations for the optimised final hull . . . . . . . . . . 515.11 Efficiency [%] of 3 to 6 bladed, 4m diameter propeller in relation to EAR 545.12 Optimal propeller characteristics for 5-bladed propeller with 4m diameter 555.13 Wake fraction for different size propellers . . . . . . . . . . . . . . . . . . 56

6.1 The critical loadcases under investigation . . . . . . . . . . . . . . . . . . 596.2 Hull Material NV36 (DNV-GL, 2016b) . . . . . . . . . . . . . . . . . . . 626.3 Plate thicknesses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 636.4 The Longitudinal Stiffeners Size . . . . . . . . . . . . . . . . . . . . . . . 646.5 Web frame size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 666.6 Midship section component names . . . . . . . . . . . . . . . . . . . . . . 696.7 Buckling check summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 716.8 Maximum generated stress for different mesh element sizes . . . . . . . . 746.9 Permissible coarse mesh yield utilisation factor λperm (DNV-GL, 2016c) . 756.10 Summary of the maximum von Mises stresses . . . . . . . . . . . . . . . 78

7.1 SOx limits inside and outside Emission Control Areas (ECA) (IMO, 2017) 867.2 NOx emission limits (IMO, 2017) . . . . . . . . . . . . . . . . . . . . . . 867.3 Comparison of marine fuels (DNV-GL, 2017a) . . . . . . . . . . . . . . . 887.4 Emission relevance and the corresponding regulations (DNV-GL, 2016a) . 927.5 Initial power demand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 937.6 2nd Level power demand . . . . . . . . . . . . . . . . . . . . . . . . . . . 957.7 Rated powers of 31D gensets at 100% MCR (Wärtsilä, 2017d) . . . . . . 987.8 Overall space requirements for 31D10V gensets . . . . . . . . . . . . . . . 987.9 Rated powers of 20D gensets at 100% MCR (Wärtsilä, 2017c) . . . . . . 99

xxii

List of Tables

7.10 Overall space requirements for 20D6L gensets . . . . . . . . . . . . . . . 997.11 Summary of different engine setups . . . . . . . . . . . . . . . . . . . . . 997.12 Weight and Volume reserve of different means for power production . . . 1027.13 Typical dimensions of SCR with built in silencer (Wärtsilä, 2015) . . . . 1077.14 Initial size estimate of exhaust casing . . . . . . . . . . . . . . . . . . . . 1077.15 Working fluid properties (Ethermo Calculation Platform, 2009) . . . . . . 1117.16 R113 working fluid (Ethermo Calculation Platform, 2009) . . . . . . . . . 1137.17 R245fa working fluid (Ethermo Calculation Platform, 2009) . . . . . . . . 1147.18 Performance data of AC fan 600x600 mm (International Marine Airflow,

2017) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1177.19 Minimum dimensions of required mooring equipment (DNV-GL, 2017d) . 1237.20 Available power at different operational points . . . . . . . . . . . . . . . 1247.21 Provided power and configuration in different operations . . . . . . . . . 125

8.1 Main hydrodynamics particulars for 7.5 m RORO Operation . . . . . . . 1308.2 Preliminary RORO displacement estimate . . . . . . . . . . . . . . . . . 131

A.1 Minimum fire integrity of all bulkheads and decks (IMO, 2009) . . . . . . IIA.2 Wave scatter diagram for the operating area (ABB, 2017) . . . . . . . . . IIIA.3 Electric balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV

xxiii

List of Tables

xxiv

1 IntroductionThis chapter introduces the background, motivation and objectives of the design project.It also outlines the methods used and assumptions made in the design process of the M/SBig Buoy.

1.1 Background

Waves4Power is a wave energy company based in Gothenburg, Sweden. The company iscurrently developing and installing wave energy converter (WEC) buoys that will aid thetransition from fossil fuels to cleaner, renewable energy sources. The buoys are plannedto be built in Runde, Norway and then transported and installed in offshore sites off thenorthern coast of Ireland. Waves4Power is still in the design process of developing thefinal buoy concept.

1.2 Project Objective

The objective of this design project is to develop a concept design of a ship that cantransport and install wave energy converter buoys for Waves4Power. The aim is toprovide the capacity to move and install 1000 buoys from Runde, Norway to the north-west coast of Ireland in one year.

The design package should include all necessary technical documents to provide a com-plete picture of the ship concept, as outlined in the technical specification. It is intendedto expose the students to a real design problem and to allow them to gain experience inthe ship design process.

1.3 Methodology

The task of developing a concept design of a ship is a large, iterative process. One methodto visualise this process is with the help of the classical ship design spiral, as illustratedin Figure 1.1. The design spiral shows the main components of the design process andthe approximate order in which they should be developed. It should be noted that whilethis design spiral is helpful to visualise the main design tasks, the tasks often happensimultaneously and the design is constantly being improved and modified.

To accomplish the concept design, the design team was divided into four subgroups tomimic the typical set-up of a shipyard design office. In this way, the subgroups areresponsible for specific deliverables outlines in the design spiral. The subgroups and theirresponsibilities are as follows:

• General Arrangement: general arrangement drawings, operational logistics, firesafety and evacuation plans, technical specification, project management

1

1 Introduction

Figure 1.1: General ship design spiral (Vossen et al., 2013)

• Hydrodynamics: hull design and optimisation, stability investigations, propellerdesign, seakeeping evaluations

• Structures: midship section drawings and scantling calculations, weight estimateand optimisation, production methods

• Machinery: engine room design, machinery selection, energy balance, on-boardsystems diagrams

1.4 Assumptions

Due to the large number of unknowns in the buoy design, the following assumptions weremade:

• The rate of production of the buoys would match the rate of installation, such thatthere is always a full load of buoys waiting at the production facilities when theship arrives.

• The maximum distance between the production facility and the installation site is600 NM.

• The ship should be able to relocate itself anywhere in the world to service futureinstallation sites.

• A minimum of 20% of the year will be lost due to harsh weather, maintenanceoperations, and unforeseen challenges.

• The centre of gravity of the unbalanced buoy is halfway between the head of thebuoy and the centre of the permanent ballast. This corresponds to 14.2 m from thebase of the buoy.

2

1 Introduction

• The ship will only be responsible for the transportation of the buoys and attachmentto temporary anchor. Another ship will be responsible for the installation of theanchors and electrical cabling.

• There will be the infrastructure available at the production facilities to bunker amore environmentally friendly fuel than diesel.

Any further assumptions made by the subgroups to accomplish their designs will be statedin the respective sections.

3

1 Introduction

4

2 Design BasisThis chapter details the fundamental background information for the design project. Itdescribes the ship’s mission, the stakeholders involved in the project and the rules andrequirements that the ship must adhere to.

2.1 Ship Mission

The mission of the ship is to provide efficient and, most of all, safe transportation andinstallation of Waves4Power ’s wave energy converter buoys. In the current installationplan, the WEC buoys will be transported from Runde, Norway to an offshore installationsite north-west of Ireland. The aim is to transport and install at least 1000 buoys peryear. While the ship is being design specifically for this purpose, efforts should be madeto maximise the flexibility of the cargo handling operations and capacity.

2.2 Stakeholders

Stakeholders can be divided into primary stakeholder, secondary stakeholders and indi-rect stakeholders. There are many stakeholders involved in the design and constructionof a ship. The primary stakeholders are the ship owner and the crew working on theship. Secondary stakeholders are the classification society and the investors. Indirectstakeholders are society (Stopford, 2009). To get a bigger overview of the complexity,Figure 2.1 is presented.

Figure 2.1: Ship’s stakeholders

5

2 Design Basis

The Figure is colour coded with green represent the primary stake holder, red representingthe secondary stakeholders and white represents the indirect stakeholders. Figure 2.1shows only an example of stakeholders and the interaction between stakeholders.

2.3 Special Requirements

When designing the M/S Big Buoy, safety and environmentally friendly technology aretwo of the main focuses. Since operating in the harsh environment of the North Sea, theoperations must be carried out in a safe manner to avoid injuries to personnel and damageto the material. To try to prevent an accident from occurring, the M/S Big Buoy’s mainramp and launch platform have been fitted with working platforms and safety harnessfor the workers, as seen in Chapter 4.2.4.2. For the ship to be environmentally friendly,a detailed study of alternative fuels has been conducted (See Chapter 7.3).

2.4 Rules and Regulations

The ship is designed according to DNV-GL (Det Norske Veritas - Germanischer Lloyd)Rules for Classification of Ships, 2017 (DNV-GL, 2017b). The following sections of therules were implemented:

• DNV-GL, Part 3, Chapter 2, General Arrangement Design• DNV-GL, Part 3, Chapter 3, Structural Design Principles• DNV-GL, Part 3, Chapter 4, Loads• DNV-GL, Part 3, Chapter 5, Hull Girder Strength• DNV-GL, Part 3, Chapter 6, Hull Local Scantling• DNV-GL, Part 3, Chapter 10, Special Requirements• DNV-GL, Part 4, Chapter 1, Machinery Systems, General• DNV-GL, Part 4, Chapter 11, Fire Safety

Further more the design team will be compliant with:• International Labour Organisation (ILO) regulations• SOLAS, Chapter II-2, Construction-Fire protection,fire detection and fire extinction• SOLAS, Chapter III, Life-saving appliances and arrangements• International Convention for the Prevention of Pollution from Ships (MARPOL)

The vessel is to fly the Norwegian flag and must thus comply with Norwegian nationalregulations in addition to the classification rules.

6

3 Logistics and OperationThis chapter details logistical and operational aspects for the design of theM/S Big Buoy.The first two sections present information about the cargo that will be transported bythe ship and the installation arrangement on site. The third section presents the resultsof the transit optimisation routine. A description of cargo handling operations on-boardthe M/S Big Buoy and the recovery and deployment procedures are presented. Finally,the preliminary cost estimation is presented.

3.1 Cargo

The primary cargo carried by the M/S Big Buoy are 38.2 m long wave energy converter(WEC) buoys as shown in Figure 3.1. The buoys have a maximum diameter of 8 m atthe head of the buoy and the shaft is 3 m in diameter. They are made of plastic whichmakes them relatively fragile. The machinery that converts the buoy’s motions into usefulenergy is found primarily where the base of the head connects with the shaft. There is apermanent concrete ballast near the base of the shaft to counter balance the machineryweight. To ensure the buoy floats at the correct draft, one ballast tank has been addedat the base of the shaft and three ballast tanks are located in the head of the buoy. Inthe un-ballasted condition, the centre of gravity of the buoy is 14.2 m from the head ofthe buoy. The buoys must be ballasted during the deployment operations. In additionto the buoys, the M/S Big Buoy must also carry one small electrical hub for every 10buoys.

Figure 3.1: Main dimensions of the Waves4Power WEC buoys

3.2 Instalment Arrangement

The buoys are destined to be apart of large energy harvesting farms in various offshorelocations. To best utilise resources, it is assumed that the buoys are arranged in circulararrays. Each array has 10 buoys that are connected to a central hub. The diameter ofthe array is assumed to be approximately 200 m. This allows sufficient clearance spaceto avoid crossing of the three anchor lines that are attached to each buoy, as well as,

7

3 Logistics and Operation

allowing for 24 m of movement in any direction. The arrays of 10 buoys are arrangedsuch that 8 small connection hubs are connected to one super-hub. It is assumed thatthe small 10-buoy arrays are arranged in a circular pattern for this as well to standardisethe lengths of connection cables. The diameter of the full pattern is approximately 900m. The full buoy arrangement contains 80 WEC buoys. A sample array is provided inFigure 3.2 and the formal drawing is given in Appendix B.

Figure 3.2: Sample drawing of the installation array

3.3 Transit Study

For the M/S Big Buoy to be considered a financially feasible investment, the ship mustcarry and install a minimum of 1000 buoys per year. It has been assumed that thefarthest distance to an installation site is 600 NM which corresponds to the western coastof Ireland, which is the halfway point between the production facilities in Norway and thepotential production site in Portugal. The approximate transit route is shown in Figure3.3.

Due to the harsh climate of the North Sea, it is assumed that approximately 20% of

8


Figure 3.3: Approximate route between production facilities and installation site

the days in the year would be lost due to harsh weather, maintenance and unforeseencircumstances. According to the wave scatter diagram for the North Sea (See AppendixA), this 20% limit corresponds approximately to sea states with significant wave heightsabove 5 m. This limits the number of usable days to 292 days per year. Using thedistance, total number of buoys and number of useful days as input, a transit study wascarried out to optimise the speed, the deployment and recovery times and the numberof buoys carried each trip. The input used in the optimisation routine can be found inTable 3.1.

Table 3.1: Transit study optimisation

Variable Range Increment

Distance 600 0 NMUseful Days 292 0 daysTotal Buoys 1000 0 buoysSpeed 5-17 1 knotRecovery Time/Buoy 1-3 0.5 hrsDeployment Time/Buoy 2-3 0.5 hrsNumber of Buoys 20-30 1 buoy

The optimisation routine yielded 25 possible combinations in which between 1001 and1225 buoys delivered. The highest number of buoys delivered was obtained by carrying 30buoys per trip and travelling at 17 knots. The minimum occurred by carrying 22 buoysat a speed of 16 knots. Since the number of useful days was already limited as input, thefinal solution was picked based on speed and minimum number of buoys carried. This

9


resulted in a ship that needs to meet the following parameters:

• Design speed: 15 knots

• Number of buoys: 25 buoys

• Recovery time/buoy: 1.5 hrs

• Deployment time/buoy: 2 hrs

With these parameters, the ship is able to deliver 1000 buoys in 40 round trips. Eachround trip takes approximately 7 days where 37.5 hours are used for loading the buoysonto the ship, 50 hours are used to launch the buoys on-site, and 80 hours are used fortransiting between the offshore farm and the production facility.

3.4 Operational Description

In this section the operations of the M/S Big Buoy are described. First a description ofthe deployment and recovery procedures is presented, following by a description of theon-board cargo handling operations. The crew hierarchy is also presented in this section.

3.4.1 Deployment and Recovery

The defining feature of the deployment and recovery operations for the M/S Big Buoyis that the buoys are moved directly from the water to the ship. This leads to an un-conventional cargo handling arrangement to fulfil this unique need. The key pieces ofequipment used in the deployment and recovery operations are the ramp, the crane andthe support frame. The details of these component are given in Section 4.2.

The recovery process is done primarily at the production site since the buoys are storedin their vertical floating positions in the water. To recover a buoy from the water, theship must first align the stern ramp with the buoy. The stern ramp will be open with asupport frame attached onto it. The crane, located on Deck 7, will assist in pulling thebuoys into a position such that the support frame can be attached to the shaft of thebuoy. The frame can then move up the ramp to the working position where the buoy canbe un-ballasted by the crew.

Once the ballast is removed, and the crew is clear of the ramp, the ramp is rotated tobe parallel to the main deck using hydraulic cylinders and the lifting winches. The buoyis then brought into the ship using translifters. Figure 3.4 shows two positions of thebuoy recovery operations: the buoy in position at the work platforms and the ramp ina position for the buoy to be off-loaded onto the ship. The complete cargo handlingdrawing can be found in Appendix B.

A control centre is positioned on Deck 7 on the starboard side of the ship, as shown inFigure 3.4. This centre is intended to provide a protected working place to supervise therecovery and deployment operations. It will be equipped with controls for the ramp, forthe clearance hatch and also a system to monitor the dynamic positioning (DP) controls.The aft control centre will have a direct communication line with the bridge.

The deployment of the buoys at the offshore installation locations is done in the reverseprocedure.

10


Figure 3.4: Buoy recovery operations

3.4.2 On-board Cargo Handling

Once on-board the ship, the buoys are moved from the main cargo deck to their respectivestorage locations. This is done using two synchronised translifters. The translifters willmove into position below the frames while the ramp is parallel to the main deck. Thetranslifters lift the buoy and frame and then can drive to the cargo elevator, as shown inFigure 3.5.

Once on the cargo elevator, the buoy is moved to the correct cargo hold based on its orderin the loading sequence. The buoys are typically loaded forward to aft starting with thefurthest buoy to port, although some exceptions are made due to the large heads of thebuoys. The buoy positions are given in the Cargo Handling drawing found in AppendixB. Once the buoy is in its place in the cargo hold, the translifter can then return to theramp are to retrieve another buoy.

3.4.3 Crew

The crew of the ship consist of 21 persons. The hierarchy can be viewed in Figure 3.6.The ship is able to operate 24/7 with a manned engine room if needed. The control officera position intended for an experienced crew member whose responsibility it is to ensurethat the buoys are installed correctly. This officer would be someone that has sailed asan second officer and has gone through quality control training.

11


Figure 3.5: On-board cargo movements from ramp to elevator

Figure 3.6: Crew hierarchy

3.4.4 Operational Limits

It is important to define the limiting sea states for the operations, in order to assure thesafety of the crew and the vessel. In Section 3.3, the total number of operating days is

12


limited to 292 days per year; however, it should be noted that this is related to openwater sailing days. When considering the limiting significant wave height for using theramp or the dynamic positioning system, the total number of operating days per year isreduced due to the limits presented in Table 3.2. These reduced number of useful days forusing the DP system and recovery and deployment operations are considered acceptablesince approximately 50% of the year is used for open water sailing.

Table 3.2: Limiting wave heights for operations

Operation WaveHeight [m]

Number ofUsableDays

Notes

Open Water Sailing 5 292Wave encounter angle mightreduce the ship’s speed

Recovery andDeployment 2 138

Dependent on the skill level ofthe crew

Dynamic Positioning 3.5 255 All heading angles

3.5 Cost Estimation

A simple cost estimation, based on the main parameters of the vessel, is presented to givethe costumer an approximate cost of production of the ship. The cost calculated for theM/S Big Buoy is based on similarly sized vessels with conventional machinery systems.Batteries and hybrid engines are not accounted for and will potentially increase the priceof the vessel. The costs of other systems are derived from similar vessels. The followingparameters are taken into account in the cost estimation:

• Steel weight [t],• Main engine power [kW],• Auxiliary engines power [kW],• Dollar per produced steel [e/t], and• Dollar per engine power [e/kW].

The cost per produced steel weight will vary depending on where the ship is built. Anestimation of 3500 e/t is used in the cost estimate. Table 3.3 presents the estimatedcost of the ship. These numbers are estimated using the variables above. When studyingother ships of the same size as the M/S Big Buoy, the total cost typically falls within thesame price range (Ramne, 2017). In Figure 3.7 an estimation of the parts in percentageis shown. The MATLAB (MathWorks, 2016) script used to calculate the cost estimationcan be found in Appendix C.

13


Table 3.3: Cost estimation

Item Price

General 4 000 000 eHull 41 500 000 eCargo Equipment 6 500 000 eEquipment Crew 4 000 000 eEngines

Main Engines 5 000 000 eAuxiliary Engines 1 500 000 eInstallation 7 000 000 e

Related Systems Machinery 5 500 000 eTotal cost estimation 75 000 000 e

Figure 3.7: Cost estimation for the M/S Big Buoy

14

4 General Arrangement

This chapter presents the general arrangement of the M/S Big Buoy. The first sectiondescribes the cargo holds and the cargo handling equipment used to move the buoysabout the ship. In the second section, the superstructure and accommodation spaces arepresented along with drawings of the cabins layouts on-board the M/S Big Buoy. Fur-thermore, the anchoring and mooring drawings is presented and all the safety equipmentincluding life saving and fire fighting. At the end of the chapter, an alternative conceptwill be discussed. The full general arrangement drawing is presented in Appendix B.

4.1 Main Profile

The centerline profile of the M/S Big Buoy is shown in Figure 4.1. This profile detailsthe major features of the ship such are the cargo holds, the engine room and the bridge.

Figure 4.1: Centerline profile

4.2 Cargo Holds

The M/S Big Buoy has three main cargo holds throughout the height of the ship as seenin Figure 4.1. The layouts of these cargo decks is presented in Figure 4.2. The details ofthe three cargo holds are discussed in Section 4.2.1 through Section 4.2.3.

4.2.1 Deck 1 - Lower Cargo Hold

The lower cargo hold is located 2.5 m above the baseline of the ship. It has a total deckarea of approximately 2500 m2 of which 370 m2 is space reserved for the cargo. This holdcan accommodate five buoys, with one resting on the elevator. The deck has a free heightof 9 m. The cargo hold is bounded by the lower deck of the engine room at the forwardend and the double side tanks on either side.

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Figure 4.2: Cargo hold layouts of the M/S Big Buoy

4.2.2 Deck 4 - Main Cargo Hold

The main deck is located 12.5 m above the baseline of the ship. This deck will serve asthe centre of the cargo handling operation. The cargo ramp used to deploy and recoverbuoys will connect to the aft end of the cargo hold. Once on-board, the buoys will bemoved to their respective storage locations using the translifters and the cargo elevator.

This hold has a total deck area of approximately 4700 m2 of which approximately 1200m2 is reserved for cargo handling including the space reserved for the elevator. Elevenbuoys are stored on this deck, including one on the elevator. This cargo hold is boundedby the engine control room at the front end, the steel hull on either side, the cargo rampin the aft.

4.2.3 Deck 7 - Upper Cargo Hold

Deck 7 is the weather deck of the M/S Big Buoy and the upper cargo hold is found onthis deck. Deck 7 is 22.5 m above the baseline and nine buoys are stored on this deck. Inaddition to the buoys, the crane used to recover the anchor lines is located on this deck.The accommodation block is found at the forward end of the cargo hold.

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4.2.4 Cargo Handling Equipment

The main cargo handling equipment consists of:

• Elevator,• Ramp,• Translifter,

• Support frame, and• Crane.

Each of them having a vital part in the operation of the ship.

4.2.4.1 Cargo ElevatorThe purpose of the elevator is to lift two buoys, one on each deck. The elevator maindimensions are 40 by 9.1 m. The elevator is dimensioned to be able to lift two buoys, twotranslifter and two support frames, one on each level shown in Figure 4.3. The structureof the elevator consist of a plate that has the same attributes as the rest of the deck. Theplate is stiffened by transverse stiffeners.

Figure 4.3: Cargo elevator

4.2.4.2 Stern RampThe ramp’s main purpose is to work as the launching and retrieving platform for thebuoys. The ramp is located in the stern of the ship and is 18 m long and 12.75 m wide.The ramp is fitted with a retractable extension which adds 10 m of length. This featureis similar to a telescopic arm that lengthens the ramp when it is in use, but reduce thelength when the ramp is stored to minimise the windage area.The ramp is unconventional as it needs to be able to rotate 180◦. The manoeuvring ofthe ramp is done by two hydraulic cylinders attached on the outside of the ramp. Tosupport the ramp when operating two winches are attached in each corner to further helpwith the support, these lifting points shown in Figure 4.4 together with the other rampfeatures.The buoys are brought onto the ramp in their frames. The ramp is equipped with guiderails into which the frames will be clamped. The frames can move along the ramp, butthe clamps prevent the frames from detaching from the ramp during the installation orrecovery operations.The ramp is also equipped with two working platform that are 9 m long and are alignedto the head of the buoy. These are installed to provide a safe working platform for theworkers when they are ballasting the buoys and installing the anchor lines.

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Figure 4.4: Stern ramp design

4.2.4.3 Crane

The crane’s main purpose is to retrieve the anchor lines for the buoy from their temporaryattachments in the water. The crane will pull the anchor lines over to the workingplatform on the ramp to allow the installers to attach them safely to the head of thebuoy.

4.2.4.4 Translifter

The main purpose off the translifter is to move the buoys while they are on-board theship. One option in model of the translifter is the C-AGV made by TTS marine AB.The C-AGV comes in fully automatic mode and can move 360◦ (TTS Port EquipmentAB, 2017c). There will be a total of four translifters on-board the ship. It is intendedthat they are paired such that two translifters are used to carry one buoy. Figure 4.10provides an example of a translifter.

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Figure 4.5: Translifter (TTS Port Equipment AB, 2017b)

4.2.4.5 Support FramesTo be able to move the buoys while on-board the ship, specialised support frames will beused. The frames are made to support the buoys weight in 4 places along the shaft whilelifting the head of the buoy off the ground. This can be seen in Figure 4.6. One basemodel option for the frames is made by TTS Marine AB and is called "The Cassette".These cassettes could be modified to fit the buoys. One benefit of the cassettes is thatthey are already dimension for use with the translifters (TTS Port Equipment AB, 2017a).

Figure 4.6: Support frame for buoys

4.3 Superstructure

The superstructure block is found in the forward end of the M/S Big Buoy. This sec-tion details the arrangement of the accommodation areas on Deck 5 through Deck 10.It excludes a description of the engine room layout, which is described in Section 7.3.The layouts for the main accommodation decks are shown in Figure 4.7 and the fullaccommodation arrangement drawing can be found in Appendix B.

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Figure 4.7: Deck 6 and 7 layouts

4.3.1 Deck 5 - Storage and Workshops

Deck 5 serves as the general workshop and storage deck for the ship. The storage roomfor spare parts for the engines, translifters, buoy frames and other machinery componentswill be located on this deck along with workshop spaces. The emergency generator andits fuel tank are also located on this deck, as close to the centre line as possible. Thechain bins for the anchors are located in the forward most compartment on this deck.

4.3.2 Deck 6 - Accommodation

Deck 6 will house the first nine accommodation cabins that will be used by the ableseamen. These cabins are concentrated about the centreline of the vessel to help reduceaccelerations due to rolling. The laundry, recreation and sauna facilities will also befound on this deck. Finally, the forward compartment is dedicated to the mooring andanchoring equipment.


Deck 7 is the main accommodation deck of the M/S Big Buoy. On this deck, nine cabinscan be found along the outboard sides of the deck. The galley, including all pantries andcold storage spaces, can be found in the forward quarter of the deck on the port side. The

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galley is connected to the mess hall through the scullery and serving area. The hospitalcabin is also located on this deck with a direct connection to the weather deck.


Deck 8 is a smaller accommodation deck with only two large cabins intended to be usedby the 1st Officer and 1st Engineer. The forward portion of the deck is assigned to bethe day room and the library. These two spaces are positioned here due to the low ceilingheight in the bow created by the high degree of curvature of the hull. It is intended thatsitting areas or shelves will be positioned here to optimise the use of the inconvenientspace. A large conference room is located on the port side in the aft part of the deck.

A exterior platform can be found immediately aft of the main accommodation block onthis deck level on either side. This is where the life boats are located. These platformsare connected to the stern of the ship using two walk-ways on either side of the ship.These walk-ways are the primary path for crossing the length of the ship without usingthe cargo holds.


Deck 9 serves as the accommodation deck for the Captain and the Chief Engineer. Twolarge cabins are located on this deck as well as a small conference room. Additionally,two small Owner’s cabins are located on this deck to be used by the owner, inspectors orguests on-board the ship.

Several platforms for ramp winches and mooring winches are located in the stern of theship. They are accessible from the walkway on Deck 8 and from ladders leading up fromthe upper cargo deck.

4.3.6 Deck 10 - Bridge

Deck 10, located at 32.4 m above the baseline, is the upper most deck of the M/S BigBuoy. The main purpose of this deck is to house the bridge and all its relevant equipment.There is a continuous stairwell that connects the bridge to the engine control room onDeck 4. There is also an exterior platform on either side of the ship that connects thebridge to Deck 7 where the lifeboats are housed. As a secondary means of escape if thelifeboats should fail, a free-floating life raft is located on each of the exterior platforms.

4.3.7 Cabin Descriptions

This section provides a brief description of the cabin furnishings and arrangements.

4.3.7.1 Crew Cabins

Crew cabins are located on Deck 6 and 7. The cabins measure 16.5 m2. They are equippedwith a bed that has the measurements of 200 cm by 90 cm, a bathroom, desk with chair,sofa, locker and a night table. A layout can be seen in Figure 4.8.

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Figure 4.8: Cabin layouts on-board the M/S Big Buoy

4.3.7.2 Officers CabinsOfficers cabin are located on Deck 8 and 9. The cabins measure 27 m2. They are equippedwith a bed that measures 200 cm by 90 cm, bathroom, locker, desk with chair and a sofawith an extra table. A layout can be seen in Figure 4.8.

4.4 Anchoring and Mooring

The mooring gear on-board the M/S Big Buoy is found in three locations: the forwardend of Deck 6, and a stern platform on either side of the ship on Deck 9. The forwardmooring gear room contains four winches, two per side, that are used to control themooring lines running from the bow to shore. The arrangement of the forward mooringgear can be seen in Figure 4.7.To maximise the cargo deck area, the mooring gear at the stern of the ship is located onraised platforms above the weather deck level. These platforms are at the height of Deck9 in the accommodation block. The platforms are accessible from the Deck 8 walkwaysand from stairs leading to the main weather deck. Figure 4.9 shows the arrangement ofthe stern mooring gear platforms.The anchoring equipment is found on the Deck 5, immediately below the mooring gearroom. The chain bins for the anchor chains can be found at the forward end of Deck4. The technical details of the mooring gear and anchoring machinery can be found inSection 7.12.

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Figure 4.9: Aft mooring gear arrangement

4.5 Safety Equipment

The safety plan and fire plan for the M/S Big Buoy meets and exceeds the requirementslaid out in SOLAS for the 22 persons compliment (IMO, 2009). The safety plan isfocused on three high risk areas where the crew is most likely to be working or spendinga significant amount of time. These areas are the bridge, the engine control room, andthe work area on Deck 4. The safety plan can be found in Appendix B.

4.5.1 Fire Safety

To design the fire systems on-board the vessel, regulations and rules needs to be followed.These regulation are governed by the flag state and enforced by the classification society.To ensure the safety of the crew, cargo and the vessel these following rules will be applied.

• DNV-GL Part 4, Chapter 11.

• SOLAS Chapter II-2

The ship is divided into sections according to SOLAS and are boundary by structuraland thermal limits. This sections are refereed to as class divisions A,B and C and needto comply to the following boundary conditions.

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4.5.1.1 Class Division

Class division A is built so it comply with one-hour standard fire test where it shallprevent passage of flame and smoke. It shall be built by steel or equivalent materialand suitably stiffened. Furthermore the insulated material used shall be non-combustiblematerial (IMO, 2009).

The class divisions are sub-categorised by:

• A-60,

• A-30,

• A-15, and

• A-0.

The difference between A-60 and A-0 is the time it takes for the temperature to rise.This means that for an Class A-60 bulkhead the allowed time before the maximumtemperature is reached is 60 minutes. An bulkhead that is defined as class A-0 willonly have a limitation of temperature but not time (IMO, 2009).

Class division B is built so it shall withstand one-half hour fire test and to preventpassage of flame and smoke. Furthermore Class B insulated material used shall be non-combustible material. Class division C shall be constructed of non-combustible material.There is no time limits set (IMO, 2009).

4.5.1.2 Integrity of Bulkheads

The ship is fitted with automatic sprinkler and fire alarm system in all accommodation,control station and other service spaces according to method "IIC" Table A.1 presented inAppendix A, which is used to determine which bulkheads are classed A, B or C division(IMO, 2009).

4.5.1.3 Fire Pumps

The fire pumps chosen for the ship are two single-stage, double-suction centrifugal pumps.The regulations state that the fire pumps shall be able to deliver at least of 4/3 of thebilge pump on-board (IMO, 2009). The fire pumps chosen have a maximum capacity of1800 m3/h at 10 bar.

4.5.1.4 Fixed Fire Fighting System in the Engine Room

The most common type of fixed fire fighting system is a CO2 (carbon dioxide) system.This system has been applied and used in many ship. The benefit of a CO2 system is thathas been proven to work. The disadvantage is that the CO2 system is very dangerouswhen used due. The CO2 suppresses all air when the system is used which is effectivein extinguishing the fire, however, if people suffocating people being inside the area offrealise. In the M/S Big Buoy the fixed fire fighting system installed will be an highpressured water mist system. The system is more safe for people inside the fire areaand can also cool surfaces much more effectively. The system shall be able to deliver 5L/m2 per minute (IMO, 2009). The system shall also be able to deliver fire fighting fora specific section and shall also be able to do a full flooding if necessary.

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4.5.2 Life Saving

The ship is equipped with two 26 persons covered life rafts that are located on Deck 8,immediately aft of the main accommodation block. They are davit launched and fullyequipped according to SOLAS regulations. These life boats serve as the primary meansof escape in an abandon ship situation. Free fall life boats were not chosen since the deckheight at which the lifeboats are stored is above the maximum drop height for free fall lifeboats. Additionally, due to the unique hull shape and cargo holds, storing the lifeboatstransversely in the superstructure was undesirable.In addition to the life boats, four inflatable life rafts are located in critical locations aroundthe hull to serve as secondary means of escape if the life boats are inaccessible. The liferafts are all free float life rafts. There are two life rafts on the mooring gear platformson either side of the ship in the stern, each with a capacity of at least 25 persons. Thereare also two 6-persons life rafts on Deck 10 immediately behind the bridge.The M/S Big Buoy is equipped with one fast rescue boat. It is located on Deck 7 nearthe stern of the ship. The location is intended to provide the fastest response to potentialman-overboard situations. Since the high risk of man overboard situation is when thecrew is working on the ramp to attach the anchor lines of the buoys, the most logicalplace to position the rescue is at the stern. A safety locker with immersion suits for allmembers of the rescue boat crew is located in the aft control centre.Life buoys are provided along the length of the ship. There are 14 life buoys total.According to SOLAS, at least two life buoys must have life lines attached to them andhalf the life buoys must be equipped with lights. Twelve life buoys have been placedapproximately every 35 m along the ships length at the height of the main length-wisepassageway of the ship. The final two life buoys are located on the main deck near thestern ramp.A total of 110 life jackets can be found on the M/S Big Buoy. They can be found in thefollowing locations:

• 1 life jacket in each accommodation cabin• 24 life jackets in each stern stairwell• 8 life jackets in engine control room• 6 life jackets in the bridge• 24 life jackets in the day room

The locations of the life jackets have been selected to ensure all crew members have accessto a life jacket at all evacuation points.

4.5.2.1 Evacuation Routes

There are three main vertical escape routes per side on-board the M/S Big Buoy: onevertical ladder set in the stern, one escape ladder at midship, and one vertical ladderset at the forward end of the cargo hold. Each of these escape routes connect Deck 2 toDeck 7. In addition to the stairwells on the side of the ship, one main stairwell is locatedon the centreline that connects the bridge to the upper engine room deck, through allaccommodation decks. A minimum of two exits have been provided for all spaces andthe primary and secondary escape routes have been marked in the Safety Plan drawing

25


(See Appendix B).

4.5.2.2 Medical Requisites

A hospital cabin has been incorporated into the design of the M/S Big Buoy on Deck7. It is located on the weather deck to allow the space to be quarantined if need be byensuring it can be closed off from the remaining accommodation block by only accessingthe cabin through the outside. The main medical locker for the ship will be found in thishospital cabin and first aid kits can be found throughout the ship, with larger ones inthe area high risk area.

4.6 Weight Estimate

The lightship weight of the M/S Big Buoy is estimated to be 13 245.3 tonnes, as detailedin Table 4.1. In the fully loaded condition, the total displacement of the ship is 19 828tonnes which includes, in addition to the lightship, 7543.6 tonnes of deadweight made upof the fuel, the ballast water and 2400 tonnes of cargo.

Table 4.1: Preliminary displacement estimate

Item Total Weight LCG TCG VCG[t] [m] [m] [m]

LightshipSteel 11 898.9 107.5 0.0 12.8Cargo Handling Machinery 350.0 20.4 2.2 16.9Accommodation 77.3 143.1 2.9 25.3Engines 308.3 108.1 0.0 6.9Propulsion Equipment 248.8 29.4 0.0 3.7Machinery Subsystems 362.0 125.7 0.0 6.8

DeadweightCargo 2400.0 72.6 -1.7 15.6Fuel 3139.4 67.7 0.0 7.2Ballast 1043.2 117.7 3.4 9.2

Total 19 828.0 95.5 0.0 11.8

4.6.1 Steel Weight

The lightship weight is estimated based on the steel structures in the midship sectionand the preliminary systems design for the ship. The steel weight is estimated on a"per webframe" basis due limited knowledge of the forward and aft structures. Due tothe significant changes in the deck structures between the cargo holds and the forwardand aft sections of the ship, the hull was divided into three sections where the midshipstructures could be scaled according to relative length of the structures and intermediatedecks could be account for. The sections are:

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Figure 4.10: Weight breakdown by component

• Aft Section: FR0 to FR33• Midship Section: FR33 to FR156• Forward Section: FR156 to FR247

For each section, a unique unit weight was estimated and multiplied by the total numberof webframes in that section. The results are presented in Table 4.2 and result in a totalsteel weight of 11 898.9 tonnes. A 25% margin was included in the steel weight estimateto account for brackets and small components that are not reflected in the unit weightestimate and to account for the large amount of uncertainties in the structure design.Combined with an estimated machinery weight of 1346.3 t, the total estimated lightshipweight is 13 245.3 tonnes with a LCG of 104.4 m, a TCG of 0.1 m and a VCG of 12.5 m.

Table 4.2: Preliminary steel weight estimate

Section Unit Weight No. Webframes Total Weight[t/webframe] [t]

Forward 143.7 30 5387.58Midship 106.2 41 5440.4Aft 77.9 11 1070.8

4.6.2 Tank Arrangement

Another important aspect to consider in the General Arrangement of a ship is the locationof the tanks and void spaces. These are important in the overall balance of the ship asthey can influence the heel and trim of the ship significantly. The tanks are distributedthroughout the hull, as seen in Figure 4.11, with the aim of balancing the heavy machineryweights in the bow while minimising the distance to the consumers. A summary of thetotal volumes of liquids on-board is presented in Table 4.3 and the full tank arrangementis presented in detail in Appendix B.

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Figure 4.11: Tank distribution throughout the hull

Table 4.3: Summary of tank volumes

Fluid Total Volume [m3]

Methanol 2750Marine Diesel Oil 395Lube Oil 117Hydraulic Oil 34Fresh Water 305Ballast 7105Heeling Water 2296

The largest tanks on-board the M/S Big Buoy are the methanol storage tanks and theballast tanks and as such they have the largest influence on the stability. There are twolarge fuel storage tanks in the furthest aft compartments of the double sides. Since themain fuel for the vessel is methanol the tanks can be placed with less restrictions comparedto more traditional fuel types such as HFO and MDO. These four tanks amount to a totalvolume of 2750 m3 for methanol storage which the amount of fuel required for an Atlanticcrossing or three round-trips. In addition to the methanol storage, there is a MDO storagetank between FR. 123 and FR. 129 on either side which amount to a total of 345 m3.Smaller daily, setting tanks and other fluids are detailed in the full tank arrangementprovided in Appendix B.

The ballast tanks are concentrated in three separate areas: the double double, at midship

28


in the double side, and in the stern. The tanks in the double bottom are largely redundantfor the M/S Big Buoy in its intended use due to the low weight-to-volume of the WECbuoys. The tanks are included, however, for potential re-purposing of the ship to carrymore standard RoRo cargo in the future. The tanks at midship and in the stern exist tocontrol the heel and trim of the vessel due to the off-centred loading of the cargo and theforward location of the machinery. There is a total volume of 4312 m3 for regular ballasttanks and a volume of 2296 m3 for heeling water.

4.6.3 Payload

The total payload of the M/S Big Buoy is 2400 tonnes. This corresponds to the weight of25 WEC buoys that each weigh 80 tonnes. As the support frames have not been designed,a 20% margin has been added to the buoy weight to account for the frame weight.

4.7 Other Concepts

While developing the concept of the M/S Big Buoy, many other concepts were consid-ered. Thee concepts presented in this chapter were disregarded due to not fulfilling therequirement or the goal set by the client.

4.7.1 Multi-hull

The multi-hull concept was disregarded due to the large number of buoys that need tobe carried. The catamaran concept would have been beneficial in minimising resistancewhen compared to a mono-hull vessel; however, the beam necessary to carry the buoysmakes this not feasible.

4.7.2 Submersible Ship

The concept of a submersible ship was discussed early in the project. The ship would havebeen able to carry an appropriate number of buoys and would have been a challengingproject. However, after comparing the submersible concept with the current design, thesubmersible was less capable of launching and recovering the buoys easily. The generalunderstanding was that the submersible ship could not preform the operation as safelyas the concept that later became the M/S Big Buoy.

4.7.3 Wind Power

Something that may be of interest is adding sails on the M/S Big Buoy to make the shipmore fuel efficient and environmentally friendly. The sail concept uses wind power tohelp propel the ship forward and overcome the water resistance. There are a few optionsfor a ship to utilise the wind power. The options considered here are regular sails, kitesails and flettner rotors.

Flettner rotors are cylinders that utilises the Magus effect to create lift force. The rotorswere first applied in year 1924 by Anton Flettner who built the first rotor ship, theBuckau. The kite concept is based on using a wind kite to assist pulling the ship forward

29


(Seifert, 2012). The kite is attached on the bow of the ship.The flettner rotors have a optimal working area when the relative wind angel is between30◦ up to tail wind. However, flettner rotors are a bigger fixed structure then the sails andkites. Fixed sails have similar work range as flettner rotors. The downside is that theyneed 7 times higher area then the flettner rotors to create the same amount of thrust.However, the fixed sails appear to have a faster payback then the flettner rotors and thekite sails. Fixed sails can be dismounted faster and some sail rigs can rotate to maximisethe angel of attack (B. Allenström & Ran, 2012).There are a few parameters to keep in mind when choosing the right sail propulsionsystem. Some parameters are, effect contribution, price and feasibility that need to betaken in mind. The kite sail provide high sail thrust but they are limited winds rangingfrom beam winds to tailwinds. The wind speed can also cause problems, since kite sailscannot work in low wind speeds.

4.7.4 Solar Panel

To utilise the sun’s power, the M/S Big Buoy could be equipped with solar panels. Oneway is to cover the roof of the bridge with solar panels. The panels could then beconnected to the main switchboard. Solar panels can generate between 100 to 150 W/m2

from solar power. The bridge roof of the M/S Big Buoy is approximately 460 m2. Ifthe whole roof is covered in solar panels, the approximate power generated from solarwould be between 4.6 to 6.9 kW, this power could be utilised to run non vital equipmenton-board the M/S Big Buoy (B. Allenström & Ran, 2012).

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5 HydrodynamicsThe following chapter will explain the hull design and hydrodynamic characteristics ofthe vessel. The limitations imposed on the design process and its influence on the mainparticulars are presented in the first section. Thereafter, the hull lines are presentedwhich can also be seen in more detail in Appendix B. The lines plan is followed by thestability calculations, considering intact and damaged situations. Furthermore the chap-ter contains the evaluation of different hull concepts and features, such as the bulbousbow. In addition, seakeeping evaluations for different concepts, followed by resistance cal-culation in calm water and in wave conditions, propeller design and dynamic positioningconsiderations are presented in this chapter.The challenge of installing the buoys in a harsh environment led to the investigation andcomparison of two different fore body shapes, the conventional open bow on deck and analternative closed bow inspired by the ULSTEIN X-BOW® design. The models werecompared both in seakeeping and resistance performances, providing valuable data in thedecision making and choice of the final hull.

5.1 Main Particulars

The main particulars are to a large degree decided by the vessels operational profileand its mission. The ship is highly specialised with a clear operational area and yearlyinstallation goal, making the vessel inherently large for a good carrying capacity. Dueto the low weight/volume-ratio of the wave buoys the main challenge in designing thehull is to fit the number of buoys required while still maintaining a seaworthy vessel withadequate seakeeping, manoeuvrability performances and stability characteristics for itsdesignated purpose.Further limitations regarding the hull design process are the matter of production com-plexity and consequently costs. Adding length to a vessel can become costly and as suchmust be kept within reasonable restrictions while still satisfying required cargo space andestimated displacement, aiming for a low block coefficient (CB). The simplification ofshapes for manufacturing (due to cost reduction) and cargo capacity thus results in aFlat of Side (FOS) and Flat of Bottom (FOB) with a small bilge radius along a largepart of the vessel. The load carrying requirements further had an influence on the vessel’sbeam and depth.A detailed summary of the hydrodynamic current main particulars are presented in Table5.1.

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5 Hydrodynamics

Table 5.1: Main hydrodynamics particulars

Parameter Value [unit]

Length overall, LOA 197.6 mLength between perpendiculars, LPP 197.6 mBreadth, B 32 mDraught, T 5 mDepth, D 22.9 mDisplacement, ∆ 19 817 tBlock Coefficient, CB 0.611 -Prismatic Coefficient, CP 0.624 -Waterplane Coefficient, CW 0.794 -Design Speed, VD 15 knotsFroude Number, Fn 0.175 -Wetted Area 6 118.772 m2

Waterplane Area 5 019.802 m2

Effective Power, PE 2.825 MWHull Efficiency, ηH 98.00 %Propeller Diameter, DP 3.50 mPropeller Efficiency, η0 66.25 %Delivered Power, PD 4.395 MW

5.2 Lines Plan

The hull shape is governed by the required size for each cargo-hold, stability requirements,wave resistance, installed equipment, manufacturing simplifications, manoeuvring andseakeeping performances. The development of the hull was a constant update, dialogue,compromise and optimisation between all disciplines of the project.The initial designs were carried out in MAXSURF Modeler (BENTLEY SYSTEMS,2015), allowing the initial plan of cargo placement and handling inside the vessel. Asthe projected evolved, the hull was constantly updated and subsequently parametricallymodelled in CAESES® to allow automatised CFD (Computational Fluid Dynamics) sim-ulations for further optimisation.The final hull shape that is a result of the iterations between disciplines, CFD, seakeepingand manoeuvring performances, detailed in Sections 5.3 to 5.7, achieved in this projectis presented in Figures 5.1 to 5.3 and thoroughly detailed in Appendix B.

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5 Hydrodynamics

Figure 5.1: Final buttocks and waterlines

33

5 Hydrodynamics

Figure 5.2: Final body plan

Figure 5.3: Isometric view of the final hull

34

5 Hydrodynamics

5.3 Stability Assessment

5.3.1 Loading Conditions

The loading conditions considered are the ones defined by the International MaritimeOrganisation (IMO) in the Intact Stability Codes:

• Fully loaded departure, full stores and fuel. Cargo homogeneously distributedthroughout all cargo compartments.

• Fully loaded arrival, 10% stores and fuel. Cargo homogeneously distributed through-out all cargo compartments.

• Ballast condition departure, full stores and fuel. No cargo.

• Ballast condition arrival, 10% stores and fuel. No cargo.

In the arrival conditions miscellaneous tanks such as bilge, sludge and grey/black water,are filled to 50%. In Table 5.2 the weight distribution of each loadcase can be seen.In addition to smaller tanks, weight used to achieve zero trim and heel are defined asmiscellaneous. It should be noted that the load cases most relevant for this vessel due toits designated purpose will be ’Fully loaded departure’ and ’Ballast condition arrival’.

5.3.2 Intact Stability

The intact stability evaluations are done for both fully loaded and ballast conditions.Both loadcases include departure and arrival conditions according to the specified criteriain IMO Resolution MSC.267(85) (IMO, 2008). Included in the intact stability analysisare equilibrium, which analyses limiting centre of gravity (KG) and metacentric height(GM), as well as large angle stability evaluations. The stability was carried out withMAXSURF Stability software.

Table 5.2: Load cases evaluated for intact stability

Item Fully loadeddeparture

Fully loadedarrival

Ballastconditiondeparture

Ballastconditionarrival

Lightship [t] 13245.3 13245.3 13245.3 13245.3Methanol [t] 2499 250 2499 250MDO [t] 330 33 330 33Consumables [t] 626 111 626 111Miscellaneous [t] 915 510 126 214Cargo [t] 2400 2400 400 400Ballast [t] 0 3266 2627 5779

Displacement [t] 20015 19816 19853 20033

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5 Hydrodynamics

5.3.2.1 Limiting KG and GMThe curve and data points of the maximum KG and minimum GM evaluation can beseen in Figure 5.4. The limiting curves are determined by the MAXSURF Stabilitymodule using wide range of different displacements. The limiting criteria to create thecurve changes as the displacement increases. Initially, the limiting criteria is the angleof maximum GZ until a displacement of approximately 27 500 t is reached. Between 27500 t and 32 500 t, the limiting criteria is the area under the righting arm (GZ) curvebetween 30 and 40 degrees. Finally, at high displacements above 32 500 t, the points onthe curve are dictated by the requirement that the GMt is at least 0.15 m.For the corresponding load cases corrected for free surface effects, the obtained KG andGM are within the created envelope in the limiting curves. Since operation in ballastmode is considered without buoys, the KG is lower here due to a relative increase inweight residing in the double bottom ballast tanks.

15000 t 20000 t 25000 t 30000 t 35000 t

Displacement

0 m

2 m

4 m

6 m

8 m

10 m

12 m

14 m

16 m

18 m

20 m

KG

Maximum KG

Limiting KG curve

Fully Loaded Departure KG

Fully Loaded Arrival KG

Ballast Condition Departure KG

Ballast Condition Arrival KG

15000 t 20000 t 25000 t 30000 t 35000 t

Displacement

0 m

2 m

4 m

6 m

8 m

10 m

12 m

14 m

16 m

18 m

20 m

GM

Minimum GM

Limiting GM curve

Fully Loaded Departure GM

Fully Loaded Arrival GM

Ballast Condition Departure GM

Ballast Condition Arrival GM

Figure 5.4: Maximum KG curve (left) and minimum GM curve (right)

Hydrostatic data for the specified loadcases can be seen in Table 5.3. Since the vesselto a larger degree is volume critical rather than tonnage critical, the displacement, andthus draft can be kept more or less the same for all operational profiles and varied withballast and heeling tanks to maintain constant draft, zero trim and heel conditions.

Table 5.3: Hydrostatic data

Parameter Fully loadeddeparture

Fully loadedarrival

Ballastconditiondeparture

Ballastconditionarrival

Displacement [t] 20069 19849 19897 20067Draft Amidships [m] 5.05 5.00 5.02 5.05Trim by stern [m] 0 0 0 0Heel stb. [deg] 0 0 0 0KB [m] 2.80 2.77 2.78 2.80KG [m] 12.20 11.77 10.40 10.08GMt [m] 8.45 9.06 10.35 10.58

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5.3.2.2 Large Angle Stability

To further evaluate the vessels stability, a large angle stability simulation was run. Thetest results in a GZ-curve for each loadcase with a heeling angle set between 0◦ and 80◦,which can be seen in Figure 5.5. The general intact stability criteria outlined in Chapter2, resolution MSC.267(85) (IMO, 2008), are passed for all loadcases. By comparing themaximum KG and GM in Figure 5.4 to the GZ curves, it is clear the stability followsa consistent trend with a more stable ship in ballast condition arrival compared to fullyloaded departure. The large transverse metacentric height (GMT) for all loadcases alsopoints to a very stable ship overall, but with the drawback of large accelerations due toshort rolling periods. This could for instance be solved by increasing the KG, effectivelyreducing the GM but might also lead to jeopardising damage stability (Lewis, 1989).

Figure 5.5: GZ-curve for the different loadcases

5.3.3 Damage Stability

An analysis of the vessels behaviour when damaged is made following the SOLAS amend-ments Chapter II-1 part B-1 (IMO, 2009), for damage stability of cargo ships with theguidance of IMO resolution MSC.216(82) (IMO, 2006). The assessment is done usingMAXSURF Stability where the subdivision index A is obtained as the sum for damageto each compartment or group of compartments. The attained index is then comparedto the required subdivision index R. Compliance with the rules is evident by A > R.The damage stability assessment is thus of the probabilistic approach where the attainedindex is the product of pi and si which represent the probability that only the watertightcompartment or group of watertight compartments under consideration are flooded and

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the probability of survival for the same cases, respectively. Furthermore, the attainedindex A is obtained for three different drafts dependant on initial loading conditions.Due to the low weight cargo of this vessel, the midship drafts for each loadcase arealmost the same (approximately 5 m), resulting in similar indices.The evaluated zones are presented in Figure 5.6. Since there are no regulations forsubdivision of zones (other than the subdivision length Ls as an extreme) the boundariesdo not necessarily coincide with bulkheads and watertight arrangements, but are placedin a manner to obtain a high attained subdivision index A. Generally a large number ofzones will give a better result but has to be balanced by an increase of computing times(IMO, 2006). The result of the probabilistic damage assessment is presented in Table 5.4.

Figure 5.6: Zone division of the vessel

Table 5.4: Damage stability results

Initial loading condition Attained index (A) Required index (R)

Deepest subdivision load line 0.804085 0.570481Partial subdivision load line 0.811125 0.570481Light service load line 0.865508 0.570481

Total Attained subdivision index 0.819185 0.633867

Although not required by regulations the floodable length could be of interest and ispresented in Figure 5.7. As can be seen in the figure, flooding the lower cargo hold wouldbe critical for the vessel due to the large size of the compartment and lack of bulkheadsand watertight sections. This case was always expected to be the worst however and isthe reason of a four metre wide side-shell structure is introduced to reduce the risk ofpossible damage reaching through to the cargo hold compartment.

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5 Hydrodynamics

0 m 20 m 40 m 60 m 80 m 100 m 120 m 140 m 160 m 180 m 200 m

Longitudinal position of compartment centre

0 m

20 m

40 m

60 m

80 m

100 m

120 m

Flo

od

ab

le le

ng

th

Floodable Length

One Compartment Flooding

Floodable Length Limit

Figure 5.7: Floodable length of the vessel

5.4 Hull Concepts Evaluation

The initial hull design was primarily based on cargo and equipment space. Along theproject development, the hull was parametrically designed, allowing punctual optimisa-tion for resistance minimisation. These points are: the bulb necessity, forward shoulderposition, waterline tangents, and general aft body performance. The main tool for theevaluation are resistance estimations through CFD simulations.

5.4.1 Bulbous Bow Evaluation

The first doubt of the initial design was the necessity of a bulbous bow. The purpose of itis to cancel the wave formed by the bow with an opposite wave. The viscous resistance isby far the largest resistance component for Fn ≤ 0.2 (Larsson & Raven, 2010), which isthe case. This led to the design and evaluation of a similar hull shape without a bulbousbow for a comparison. The expected result would be a similar, or even slightly higher,wave making coefficient, but a reduction of the friction coefficient, thus resulting in alower total resistance.The simulations were executed in similar conditions: potential flow panel method, bound-ary layer, and a global viscous flow RANS (Reynolds-averaged Navier-Stokes) solver withSHIPFLOW, fine mesh. The results are presented in Figure 5.8 and Table 5.5.The results did not exactly follow the expected trend. The wave resistance coefficientsignificantly decreased (≈ 30%), which is beneficial and can be explained. As the bulbevaluated was a general bulb and not optimised to the vessel, the wave generated did notcancel the bow wave, resulting in added wave resistance. Although an optimised bulbcould lower the wave resistance, it would hardly be enough to make significant difference

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Figure 5.8: Wave pattern and pressure distribution for hull with bulbous bow (upper)and without a bulbous bow (lower)

Table 5.5: Resistance comparison with and without bulbous bow

Evaluated properties With bulbous bow Without bulbous bow

Wave resistance coeff., CWTWC [-] 0.000252 0.000176Pressure viscous resistance coeff.(model), CPV [-] 0.0002270 0.0005105

Wetted surface coeff., Sref [-] 0.1664 0.1607Form factor, k [-] 0.0698 0.1570Wave making resistance, RW [kN] 44.07 29.73Total towing resistance, RT [kN] 383.51 379.60Effective power, PE [MW] 2.959 2.929

in the total resistance, compared to the friction resistance it generate.

The viscous pressure resistance coefficients (CF and CPV ) increased when the bulb wasremoved, but with the lower wetted surface the form factor increased and lowered thetotal resistance.

By removing the bulb, as presented in Table 5.5, the required effective power reduces byapproximately 2%. The wave resistance reduced from 44.07 kN to 29.73 kN, which arebetween 12% and 8% of the total resistance. Thus, the possibility of further optimisingthe model without a bulbous bow, summed to the lower wetted surface area, led to thefinal concept to be without a bulbous bow.

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5.4.2 Concept Optimisation

The fact that the friction resistance plays a major role in this Froude number (Fr =0.175) and the wave resistance is of less importance, does not mean that there is no needfor optimisation. Thus, ensemble investigations were performed to evaluate the waveresistance coefficient of different geometry possibilities without drastically changing themodel.By opting not to have a bulbous bow model, the quantity of parameters to optimisedecreased. The forebody parameters evaluated were: horizontal entrance angle at thewaterline, fullness of the bilge at different sections, the vertical waterline tangent and theforward shoulder position.One of the possibilities that aroused by opting to use a hull without a bulb, is the shift ofthe forward perpendicular to almost 200 m, maximising the potential of the vessel withoutchanging its class division. This requires a totally vertical stem (no bow overhang), butit does not compromise any deck space.By systematically varying hull parameters, mainly in the forebody, the wave resistancewas decreased by approximately 5 kN, as presented in Table 5.6 (the methodology ofcalculation is presented in Section 5.6.2). The visual difference can be seen in Figure 5.9.

Table 5.6: Resistance comparison of the baseline and optimised hull without bulbous bow

Evaluated properties Baseline Optimised

CWTWC [-] 0.000176 0.000145CPV [-] 0.0005105 0.0004226RW [kN] 29.73 24.55RT [kN] 379.60 368.99PE [MW] 2.929 2.847

By evaluating the results, the optimisation was able to reduce the wave making resistanceby approximately 17.50% and the total resistance by 2.80%. This already representssubstantial savings in fuel during the life-time of the vessel.

5.4.3 Concepts Evaluation

As the operation area of the M/S Big Buoy is considered to be a harsh environment,it became necessary to evaluate different hull concepts, specifically their seakeeping per-formance (detailed in Section 5.5). The two concepts evaluated are the conventionalforebody (also called as open bow) without a bulb and an ULSTEIN X-BOW® inspired(closed bow). The body plan of the models are compared in 3D detail of the forebody inFigure 5.10 and hull lines from the FP in Figure 5.11.The main difference is how the forebody enters in the water when pitching in waves.The conventional forebody has a concave outside shape while the other has a convexoutside shape. This will directly impact how vertical forces and accelerations are dumpedwhen pitching, resulting in different seakeeping responses and added wave resistances (theresults are presented in Sections 5.5 and 5.6.2.2).

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Figure 5.9: Wave pattern and pressure distribution for the baseline hull (upper) and theoptimised (lower)

Figure 5.10: Hull forebody shape, conventional open bow (left) and closed bow (right),3D detail

In a space perspective, the new proposed concept has less deck space than the conven-tional, but it is completely protected from the weather. The curvatures on the hull mightalso compromise space for the cabins, mooring gear compartments and other areas. Suchnew challenges must be studied and solved together with the General Arrangement work

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5 Hydrodynamics

Figure 5.11: Hull forebody lines, conventional open bow (blue) and closed bow (red)

group.

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5 Hydrodynamics

5.5 Seakeeping

The operational profile and designated task for this vessel sets high requirements onthe vessels ability to maintain acceptable seakeeping characteristics. Furthermore thegoal of installing 1000 buoys per year in a relatively harsh environment further add tothe challenges faced when designing the vessel. To give a first glimpse of the vesselsbehaviour in the operational area a seakeeping analysis has been made in the softwareOCTOPUS office (ABB, 2017).With the designed installation window of approximately 292 days per year, as presentedin Section 3.3, and with the wave scatter diagram (Table A.2), generated from the JON-SWAP spectrum for the areas of operation, it is possible to estimate in which sea statethe M/S Big Buoy should be able to fully operate. This corresponds to a significant waveheight of 4.5 m. Thus, the seakeeping analysis is made for significant wave heights up to5 m for the speeds 3.75, 7.50, 11.25 and 15.00 knots with 19 headings evenly spread from0◦ to 180◦ using the JONSWAP wave spectrum.

5.5.1 Seakeeping Performance Evaluation

To evaluate if the vessel is suitable of working within the sea states, some limiting criteriamust first be defined to assess its ability of obtaining a desirable response to the varioussea states. In this case, a comparison has been made with the seakeeping criteria statedin Nordforsk (NordForsk, 1987). The parameters compared in this case are the RootMean Square (RMS) of the vertical and lateral accelerations at the bridge, the aft rampand the FP, in addition to the RMS roll degree for each sea state. The criteria statedin Table 5.7 are considering heavy manual work. Furthermore the Principles of NavalArchitecture (PNA) Chapter 8, Section 7 (Lewis, 1989) has been used as a reference tofurther evaluate if the obtained ship acceleration RMS are within acceptable limits inaddition to comparing slamming frequency and Motion Sickness Index (MSI). Lastly, theprobability of propeller emergence was evaluated, where propeller emergence was definedas 25% of the disk emerging from the water. This was not compared to any criteriahowever since no applicable limits could be found, which on the other hand also provedto be unnecessary since the risk of propeller emergence is on the order of 0.1%. Allcomparisons done can be seen in Table 5.7.Although the RMS method is a useful tool to compare and evaluate seakeeping charac-teristics, of further interest are the motions in a specific sea state or group of sea states.With this approach the operation envelope of the vessel could be deduced from the anal-ysis of separate sea states to obtain the number of sea states where the vessel performsbest, up to the necessary operational days to reach the target goal of wave buoys instal-lations. As was seen in the seakeeping assessment, the vessels behaviour is to a largerdegree governed by wave period than significant wave height, due to a natural rollingfrequency in regions often occurring in the Northern Sea, as approximated by Equation(5.1) obtained from the IMO intact stability code (IMO, 2008).

Tr = 2 · C ·B√GMT

(5.1)

with: C = 0.373 + 0.023(B/T )− 0.043(LWL/100)

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Table 5.7: General seakeeping results (final hull) and operational criteria

Description [unit] RMS (results) Criteria Source

Roll Motion ◦ 5.96 6 NordforskVertical Acceleration (Ramp) g 0.185 0.15 NordforskLateral Acceleration (Ramp) g 0.126 0.07 NordforskVertical Acceleration (Bridge) g 0.176 0.15 NordforskLateral Acceleration (Bridge) g 0.252 0.12 NordforskVertical Acceleration (FP) g 0.224 0.275 NordforskMSI (Bridge) % 10.8 35 PNASlamming Frequency times/hr 10 12-30 PNA

The natural rolling frequency of the vessel is estimated to be between 8.56 and 9.58 sec-onds, depending on the loading condition. Encounter frequencies in this domain shouldthus try to be avoided by either changing heading or speed, to reduce the risk for syn-chronic rolling which could amplify the roll motion of the ship. The amplification ofthe motions can be seen in Figure 5.12, where the MSI on the bridge is evaluated fromTz = 6.5 s to Tz = 9.5 s for a Hs = 4 m sea state.

5.5.2 Concept Comparison and Optimisation

As can be seen in Table 5.7 the designated vessel is just shy of reaching the generalseakeeping criteria, which proves the difficulty of designing a vessel for the stated task.Several changes were made to the initial hull concept to improve its seakeeping character-istics in an attempt to reach the defined criteria. A comparison of the RMS seakeepingcharacteristics for the initial and final design can be seen in Table 5.8.

Table 5.8: Comparison of seakeeping characteristics between initial and final design

Description [unit] Initial Design Final Design

Roll Motion ◦ 19.39 5.96Vertical Acceleration (Ramp) g 0.273 0.185Lateral Acceleration (Ramp) g 0.311 0.126Vertical Acceleration (Bridge) g 0.232 0.176Lateral Acceleration (Bridge) g 0.717 0.252Vertical Acceleration (FP) g 0.261 0.224MSI (Bridge) % 16.4 10.8Slamming Frequency times/hr 11 10

As can be seen in Table 5.8, large improvements were made to the hull concept. Adrastic change was made to the initial hull by introducing a redesign of the bow, a closedbow inspired by the so called ULSTEIN X-BOW® which lead to instant improvements,especially for pitch and heave motion, but also slight improvements overall. An example

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5 Hydrodynamics

Figure 5.12: MSI performance for the final hull for Tz = 6.5 s (upper left), Tz = 7.5 s(upper right), Tz = 8.5 s (lower left) and Tz = 9.5 s (lower right)

of that is presented in Figure 5.13, comparing vertical accelerations at the aft rampposition for a common sea state of 2 m wave height and 8.5 seconds of zero-up crossingperiod.

The same trend follows when evaluating other sea states, wave periods and positionsalong the ship. The closed bow with a concave shape above the waterline results inbetter damping of the motions.

In addition to the redesign of the bow, a 100 m long and 0.75 m high bilge keel wasintroduced along the bilge to further dampen the roll motion. Lastly a passive anti-roll tank was designed above the weather deck just aft of the superstructure, mainly tocounteract the roll motion but with the added benefit of reducing GM which helped withthe vessels accelerations. The anti-roll tank reduces RMS roll motion with around 1.5%and reduces the GM with 0.25 m, corrected for free surface effects.

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Figure 5.13: Vertical accelerations in a sea state with Hs = 2 m and Tz = 8.5 s (initialto left and final to the right)

To further reduce the motions, it is recommended to fill the ballast tanks during wavebuoy installation operations for extra displacement, which was the case evaluated inTable 5.7 regarding accelerations and roll motions. This action will improve all criteriaaround 10% except for lateral accelerations at the bridge which stays almost constant.To conclude the design improvements made a large positive impact in the motions, butfurther improvements must be made to reach the operational seakeeping criteria goals.A visual representation for the two designs regarding roll motion can be seen in Figure5.14.

Figure 5.14: Roll motion comparison for the different hulls (initial to left and final to theright) concepts in a sea state with Hs = 3 m and Tz = 8.5 s.

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5 Hydrodynamics

5.5.3 Dynamic Positioning and Station Keeping Capabilities

In addition to a workable environment for the crew as defined by the seakeeping criteria,the vessel must also be able to maintain its position for safe WEC installation. This ledto the necessity of a dynamic positioning (DP )system installed aboard that can maintaina desired station or heading automatically. To evaluate the vessels station keeping abilitya DP capability plot is often used (Herdzik, 2013).

To produce a DP capability plot the environmental forces have to be determined. Theforces are often subdivided into wind, current and wave drift forces. Due to endlesspossibilities of combinations, the forces are assumed coincident in direction and correlatedaccording to Table 5.9.

In the case of wind forces they are considered on the vessel’s hull above the waterline,where the wind speed is a one minute mean at a height of ten metres. Since the wind speedvaries with height, it is also scaled by a factor accordingly to the procedure recommendedin IMCA M 140 Rev. 1 (The International Marine Contractors Association, 2000).

The current forces are determined according to the guidelines by Oil Companies Inter-national Marine Forum (OCIMF, 1994), where the current coefficients are obtained fromgraphs. It should be noted the graphs presented in the guidelines mainly are for VLCCs(Very Large Crude Carriers) and as such not necessarily represent the analysed hull.On the other hand the current forces also have the smallest magnitude compared to theother environmental forces. The current velocity, VC , is estimated to be 0.5 m/s in allsea states.

For wave forces, only the second order drift forces and moments have to be considered,since the first order forces are not counteracted by a DP system (Herdzik, 2013). Thewave forces can be determined by either scaling wave drift coefficients for a similar vesselor by a hydrodynamic computer program. In this case the forces are determined byMAXSURF Motions using the panel method as opposed to strip theory, and then scaledby LPP and wave amplitude.

The environmental forces are then compared to the possible forces generated by theinstalled thrusters and Azipods, for each heading and sea state. The force output from athruster can only be determined by full-scale bollard trials, but since this is not possible inthis case, the efficiency of the installed propulsors are assumed according to the guidelinesin IMCA M 140 Rev. 1. The comparison is in essence a force balance where the objectiveis to find the points where the sum of forces and moments are zero for a given heading,wind speed and correlated wave height. The limiting states can then be plotted in apolar plot, effectively creating an envelope for the vessels ability to hold its position as afunction of heading and wind speed. The results are presented in Figure 5.15.

To summarise the results, the currently installed power is capable of maintainingM/S BigBuoy’s position in all headings in sea states with HS up to 3.21 m, with correlated windspeeds according to Table 5.9. It is also capable of maintaining its station in sea stateswith significant wave height up to 5.07 m in beam seas. It must be noted however thatthe vessels capability should not be confused with operational condition. In more severesea states the M/S Big Buoy would have to abort WEC installations before reaching itsoperational limit, due to large motions and accelerations as deduced from the seakeepinganalysis. Since the operation of WEC installation will occur in smaller Hs than these, it

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Table 5.9: Correlation of wave height, crossing period and wind speed (The InternationalMarine Contractors Association, 2000)

Significant Wave Height, Hs Crossing Period, Tz Wind Speed, Vw[m] [s] [m/s]

1.28 4.14 2.51.78 4.89 52.44 5.72 7.53.21 6.57 104.09 7.41 12.55.07 8.25 156.12 9.07 17.57.26 9.87 208.47 10.67 22.59.75 11.44 2511.09 12.21 27.512.50 12.96 3013.97 13.7 32.515.49 14.42 35

0°

30°

60°

90°

120°

150°

180°

210°

240°

270°

300°

330°

0 m/s

10 m/s

20 m/s

30 m/s

40 m/s

DP Capability Plot

DP Operational Envelope

Figure 5.15: DP capability plot accordingly to heading angle and wind speed

can be concluded that the current propulsion power is able to cover the vessel’s needs forDP.

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5.6 Resistance Estimations

This section presents the estimated resistance of the vessel accordingly to different theoriesand through CFD simulations. The CFD simulations are carried out both in calm waterand in sea waves conditions.

5.6.1 Holtrop-Mennen

Normal approximation procedures such as Series 60 and Holtrop-Mennen works well forship-shaped structures (Larsson & Raven, 2010). With the aid of MAXSURF Resistancemodule, the total resistance can be estimated for different speeds. Figure 5.16 presentsthe initial towing resistance (RT ) estimations, approximately 430 kN.

10 11 12 13 14 15 16 17 18 19 20

Ship Speed [kn]

0

100

200

300

400

500

600

700

800

900

1000

Resis

tance [kN

]

Resistance vs Speed

Holtrop

Series60

Design Speed

Figure 5.16: Estimated towing resistance

The effective power for the propulsion system can be found by multiplying the operatingspeed by the vessel speed, Equation (5.2) (Lewis, 1989).

PE = RT · VD (5.2)

The estimated effective power with Holtrop-Mennen methodology is 3 320 kW.This estimation was performed only for the initial concept of conventional hull withbulbous bow. As the methodology does not take into account local changes in the hull,

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the resistance for the optimised and alternative concepts are presented only with the CFDestimations, Section 5.6.2.

5.6.2 CFD Resistance Estimations

The CFD simulations were carried out with the parametrically designed models in SHIPFLOW,connected to CAESES® (FRIENDHSHIP SYSTEMS, 2017). The parametrically de-signed hull allowed for automated performance evaluation and eased the decision making.All simulations are based on the same environment configurations, including the meshsize, in order to have comparable results.CFD simulations, besides providing visualisation of the physical phenomena of the vesselsmovement, provide detailed resistance components and total resistance, both in calmwater and in wave conditions.

5.6.2.1 Calm Water Resistance

The calm water estimations, using the ITTC-78 (1978 International Towing Tank Con-ference) methodology, are scaled from the CFD calculations on 6 m models of the fullscale hull. The final hull, based on the decision taken due to seakeeping performances(Section 5.5), was built from scratch and systematically optimised to be in the same levelor better than the conventional optimised hull without bulbous bow. The results of thescaling are presented in Table 5.10, being also compared to the optimised conventionalhull without bulbous bow.

Table 5.10: CFD resistance estimations for the optimised final hull

Evaluated properties Conventional Final hull

CWTWC [-] 0.000145 0.000121CPV [-] 0.0004226 0.0001342Sref [-] 0.1614 0.1546k [-] 0.12999 0.04175RW [kN] 24.55 22.29RT [kN] 368.99 366.09PE [MW] 2.847 2.825

5.6.2.2 Added Wave Resistance

When sailing in open sea, ships are subjected to wind, waves and ocean currents that di-rectly impact the performance of a vessel. In order to investigate the added resistance dueto waves in different seas states, systematic evaluations were carried out with SHIPFLOWmotions module connected to CAESES®. It evaluates the added wave resistance in timesteps, taking into account surge, heave and pitching motions due to waves.A full detailed investigation would consider the specific route and the most commonheading angles of the incoming waves. For the simplicity of this project and due tocomputational power and time restrains, different sea states were evaluated as regularperiodic waves and only in 180◦ heading angle, being the direction that has the highest

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5 Hydrodynamics

Figure 5.17: Final hull complete CFD simulation

impact on the propulsion system.The selected sea states for evaluation ranges from 1 m to 5 m wave height and thewave period with highest probability of occurrence. To be able to interpolate valuesaccordingly, two surrounding wave periods were also simulated for each wave height. Theresults of the performance of both evaluated hull shapes is presented in Figure 5.18.Figure 5.19 presents the result for the closed bow hull in a 7 m wave height sea state.The conclusion taken from Figure 5.18 is that the conventional open bow hull shape hasa marginal advantage over the closed bow hull in every sea state. This difference canbe neglected as the closed bow is 12 m longer in order to take advantage of the verticalstem. This possibly biases the results.By combining with the results from Figures 5.18 and 5.19, it becomes clear that a 7m wave height sea state is not recommended. The vessel becomes highly susceptible toslamming and also requires considerably more power than in calm water.

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Closed Bow Hull

100

200

300

400

500

600

700

800

900

1000

1 1.5 2 2.5 3 3.5 4 4.5 5

Hs [m]

4

4.5

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5.5

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9

9.5T

[s]

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Added W

ave R

esis

tance [kN

]

Open Bow Hull

100

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Hs [m]

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s]

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900

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Added W

ave R

esis

tance [kN

]

Figure 5.18: Added wave resistance for the closed bow (left) and open bow (right)

Figure 5.19: The final hull sailing at 15 knots in sea state 5 (7 m wave height and 9.5wave period)

5.7 Propeller Design

The propeller design process can be started based on the operational requirements, resis-tance calculations and the minimum operational draft. The operation of installation ofWEC’s requires dynamic positioning (DP), resulting in the selection of a pair of azimuththrusters (2 propellers). The resistance estimations presented in Section 5.6.2.1 dictate

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how much thrust the propellers need to produce. The minimum operational draft limitsthe propeller size to ensure propeller emergence and reduce caviation.

5.7.1 Wageningen B-Screw Series

The initial design point was the Wageningen B-Screw Series, that evaluates and providethe efficiency of fixed-pitch propellers (FPP) between 2 to 7 blades and blade-area ratiosbetween 0.30 and 1.05 (van Lammeren, Manen, Oosterveld, & Basin, 1969). The inputsare the propeller diameter (DP ), number of blades (Z), the expanded area ratio (EAR),vessel speed, required thrust, the wave fraction and the pitch-ratio range. The outputsare the propeller efficiency (η0), optimal rotation speed, thrust and torque coefficients(KTT and KQ, respectively) for the range of pitch-ratios (PD) and advance coefficient(J). The utilised code is presented in Appendix C.

The evaluation and choice of the propeller was realised based on a systematic approachvarying the number of blades and EAR for propellers size ranging between 3.5 and 4.25m. The mean wake fraction is 0.128, and the maximum wake in the disc area is 0.348,both results extracted from SHIPFLOW simulations (Section 5.6.2). The required thrustwas corrected with a thrust deduction factor of 0.12, as recommended for ships with twopropellers and conventional aftbody (MAN, 2011).

After estimating and evaluating the loads and the hull displacement, the ideal final draftis expected to be around 5 m. This led to the choice of a 4 m diameter propeller, aimingthe highest efficiency. The choice of the number of blades took into consideration theefficiency in relation to EAR. The study results are presented in Table 5.11.

Table 5.11: Efficiency [%] of 3 to 6 bladed, 4m diameter propeller in relation to EAR

Z EAR 0.40 0.45 0.50 0.55 0.60 0.65

3 69.42 68.70 67.94 67.15 66.35 65.604 68.46 68.21 68.12 67.98 67.78 67.565 68.24 68.24 68.22 68.34 68.40 68.426 67.18 67.44 67.74 68.02 68.40 68.42

The choice of the number of the blades, after evaluating the results in Table 5.11, wasa 5-bladed propeller. The reason is that a 5-bladed propeller, for this case, has a lowerη0 variation with the EAR. This allows more flexibility in the choice of the design EARduring the caviation design phase.

Expanding the results from the Waningen B-Screw Series for the 5 bladed propeller, Table5.12, it was possible to chose the initial propeller. The initial chosen propeller becamea 4 m diameter, 5-bladed and 0.60 EAR . This allows for further increase in EAR andefficiency with further optimisation tools.

5.7.2 OpenProp Optimisation

OpenProp can provide further optimisation of the propeller geometry. The software,based on MATLAB (MathWorks, 2016) functions, is capable of manipulating the rake,

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Table 5.12: Optimal propeller characteristics for 5-bladed propeller with 4m diameter

EAR 0.40 0.45 0.50 0.55 0.60 0.65

rpm 104.06 103.98 111.87 114.91 116.57 117.55J 0.97 0.97 0.9 0.88 0.87 0.86KTT 0.26 0.26 0.23 0.22 0.21 0.21KQ 0.06 0.06 0.05 0.04 0.04 0.04η0 [%] 68.24 68.24 68.22 68.34 68.41 68.42PD 1.4 1.4 1.26 1.21 1.19 1.18

the skew, the pitch, the thickness and the chord along the blade length to improveefficiency according to the Unified Rotor Lifting Line Theory (Epps & Kimball, 2013).Inserting the chosen design from Section 5.7.1, and using the default values provided byOpenProp, returns a propeller efficiency η0 = 69.09%. There is a possibility of furtherimprovement in the blade parameters.

5.7.3 Cavitation Evaluation

The initial propeller cavitation evaluation was realised based on Keller’s criteria and anOpenProp pressure plot, presented in Figure 5.20. The result from the Keller’s criteria isa required EAR of 0.15, far below the trivial EAR. Further analysing the pressure on theblades in Figure 5.20, no initial concern is raised and no changes in propeller parameterswas necessary.

Figure 5.20: Pressure distribution on the blade area

5.7.4 Final Propeller Choice

Ideally, the larger the diameter, higher the propeller efficiency. In practice the propellerdiameter is limited in clearance to the hull (avoiding pressure impulses and vibrations),operational draft and propeller emergence in sea wave conditions.With a 4 m diameter propeller, the clearance to the final hull is approximately 0.5 m,

55

5 Hydrodynamics

being lower than 25% of the diameter as recommended (Babicz, 2015). The minimumoperational draft is also reduced. Thus, the reduction of the propeller diameter is studied,from 4 m to 3.5 m.By reducing the propeller diameter, the wake fraction (calculated by SHPFLOW) is alsoreduced, as seen in Figure 5.21. This also impacts the propeller efficiency, as a lowerwake fraction on the propeller disc results in higher efficiency. The results are presentedin Table 5.13.

Figure 5.21: Wake fraction disc for 3.50, 3.75 and 4.00 m propeller diameter

Table 5.13: Wake fraction for different size propellers

DP 3.50 3.75 4.00

Mean wake fraction 0.102 0.116 0.128Maximum wake 0.259 0.300 0.348Hull clearance [%] 28.57 20.0 0 12.50η0 (OpenProp) [%] 66.25 67.69 69.09

The propeller emergence for significant wave height, HS = 1.5 m and zero-up crossingperiod, TZ = 6 seconds, which is one of the most common seas states (Table 5.5) iscompared in Figure 5.22. In other seas states, the behaviour follows the same pattern.By analysing the propeller emergence, it becomes clear that it is beneficial to reducethe propeller diameter to increase the operational envelope without reducing the shipvelocity. The 2.84% reduction of efficiency is a sacrifice that will be compensated with thelarger operational window, operational draft, manufacturing cost and pressure resistanceavoidance. Therefore the final propeller choice is a 3.5 m diameter, centred at 8 m fromthe centreline, 8 m from the aft perpendicular and 3.6 m above the baseline.A similar investigation for a 3.5 m propeller was carried out in Sections 5.7.1 to 5.7.3,evaluating efficiency, operational parameters and caviation. The final propeller has anefficiency estimated of 66.25%, running at 151 rpm, advance coefficient 0.788 and freefrom cavitation.The detailed propeller design point characteristics are presented in Figure 5.23, beingfully capable to provide efficient propulsion to the M/S Big Buoy even in an eventualload increase. A 3D model representation of the chosen propeller is presented in Figure5.24.

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5 Hydrodynamics

Figure 5.22: Propeller emergence comparison between 3.5 m diameter (left side) and 4m diameter (right side) in a sea state of Hs = 1.5 m and Tz = 6 seconds

0 0.2 0.4 0.6 0.8 1 1.2

J

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

KT

T,1

0*K

q,E

TA

T

KTT

10*KQ

ETAT

Figure 5.23: Open water diagram for the final chosen propeller

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5 Hydrodynamics

Figure 5.24: Final propeller 3D visualisation

58

6 StructureThe ship’s structural analysis can be divided into primary, secondary and tertiary levels.The primary level loads affect the whole hull strength, the girder, the secondary considersthe loads that occur to the skin structure of the ship (side walls, bottom and deck) andthe tertiary level the forces, strength, and bending response of individual sections of thehull plate between the stiffeners, as well as the behaviour of individual stiffener sections.The procedure of dimensioning the structures in this project begins with the primary andends with the tertiary analysis.The M/S Big Buoy is designed with a longitudinal framing system, which is good forsustaining the global bending moment. The vessel is considered to be a ship very similarto a RORO vessel, mainly because of the lack of transverse bulkheads and pillars in thecargo holds.

6.1 Design Loads

The investigation of the design loads acting on the ship’s hull should consider severaldifferent loadcases. The condition which results in the largest stresses on the hull girderis the one that is considered as the critical load condition.The two loadcases are Full Load - No Ballast (Case A) and No Load - Full Ballast (CaseB). The two main load conditions are described in Table 6.1. Despite the design draftbeing 5 m, the hull structures are dimensioned using a draft of 7.5 m with the exceptionof the outer hull plating. The reasons for these exceptions are explained in Section 6.1.2.The increased draft is used to ensure that ship’s structure will be able to withstand theincreased hydrostatic and hydrodynamic pressures if the vessel is used as a RORO in thefuture, as explained in Chapter 8.

Table 6.1: The critical loadcases under investigation

No. loadcase Design Draft [m] Calculation Draft [m]

A Full Load - No Ballast 5 7.5B No Load - Full Ballast 5 7.5

6.1.1 Global loads

The loads acting on the entire hull consist of: mass of the ship, buoyancy, cargo loadand ballast water. Figures 6.1 and 6.2 show the mass, buoyancy, the shear force and thebending moment distribution due to the global loads for loadcase A and B, respectively.The maximum bending moment for load case B is larger than load case A; however,both maxima occur around the middle of the ship. This justifies the simplification of thestructural analysis to focus on this area.

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6 Structure

Figure 6.1: Loads, shear forces and moments acting on the hull in still water, loadcase A

Figure 6.2: Loads, shear forces and moments acting on the hull in still water, loadcase B

6.1.2 Local Pressures

The local pressures acting on the midship section are calculated using Nauticus Hull® (DNV-GL AS, 2017). All the results from Nauticus Hull are calculated based on DNV-GL rules.This is an automatic procedure of the software, increasing the reliability of the outcome.

It should be noted that the 7.5 m draft is used to get conservative results for the upperside and weather deck plates, as described at the beginning of this chapter. Due to thelow weight-to-volume ratio of the buoys, an assumed cargo load of 1 t/m2 is used todimension the deck structures. This again ensures the ship will be suitable for otherpurposes, if necessary.

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6 Structure

The wing tanks and double bottom are assumed to be connected. This means that theballast water is filled and connected in both the wing tanks and the double bottom. Asa result, the pressure is high on the outside bottom as a result of the 12.5 m hydrostaticpressure. Consequently, this will result in the highest ballast water pressure for the doublebottom structures.However, considering loadcase B, the 5 m draft is more conservative in the dimensioningof the outer side wall as well as the outer bottom shell. The pressures derive primarilyfrom the sea and ballast water. A higher draft will result in higher sea pressure on theoutside bottom and the outside side wall, which will counteract with the pressure fromballast water. The pressure magnitude of ballast water is always higher than sea pressure.Therefore, the 5 m draft will result in a more critical condition.Figure 6.3 shows the critical pressures distribution at the port side midship section, andit is symmetric for the starboard side. These pressures are utilised for the calculation ofthe structures of the midship section as detailed in Section 6.2.

Figure 6.3: Pressure Distribution at the midship Section

6.2 Midship Section

The primary aim of the structure analysis is to design the midship. The reason is thatthe highest demand for structural strength is located close to half the length of the vessel.As a result, by designing the midship cross section, the structural arrangement can beextended across most of the length of the vessel. The detailed drawing of the midship

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6 Structure

cross section is presented in Appendix B.

6.2.1 Hull Material

The selected material is the NV 36 steel, due to its yield stress of 355 MPa and its tensilestrength between 490 MPa to630 MPa, being suitable and affordable for shipbuilding.The material is low cost as well. Additionally, NV 36 steel is a common type of steelfor shipbuilding and platforms. It was defined by DNV-GL, and contains several subcategories which depend on the mechanical requirements of specific position of plates.For example, the temperature requirements which are presented in Table 6.2 (DNV-GL,2016b).

Table 6.2: Hull Material NV36 (DNV-GL, 2016b)

Impact energy, average minimum [J ]Elongation Temperature t ≤ 50 50 < t ≤ 70 70 < t ≤ 150

A5 [mm] [mm] [mm]Grade [%] [◦C] L T L T L T

NV A36 21 0 34 24 41 27 50 34NV D36 21 -20 34 24 41 27 50 34NV E36 21 -40 34 24 41 27 50 34NV F36 21 -60 34 24 41 27 50 34

6.2.2 Plates Thicknesses

For the midship section, the plate thicknesses are calculated based on the local pressureswhich are derived from the hydrostatic and hydrodynamic sea pressures, the ballastwater pressures, the cargo weight and the weather conditions. After the local pressuresare determined, the moments can be calculated according to the beam theory and morespecifically using Equation 6.1 (Ringsberg & Thelandersson, 2016).

Mmax = wl2s12 (6.1)

where: Mmax is the maximum bending moment which can also be used as the criticalmoment, w is the distributed pressure load, ls is the span of the plate which in this caseis the distance between two longitudinal stiffeners.Furthermore, the critical moment can be used to determine the minimum thickness ofthe plate. The critical moment is a function of the thickness, according to the Equation(6.2) (Ringsberg & Thelandersson, 2016).

σy = Mmax

IpZp (6.2)

Ip = 112 lpt

3p (6.3)

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6 Structure

where: σy is the yield stress of the material, Ip is the moment of inertia of the plate, andZp is the distance to the neutral axis of the plate. In order to get the maximum stress,Zp should be the distance to the surface of the plate, lp is the length of the plate, and tpis of the plate.After solving Equations (6.1), (6.2), and (6.3), the thickness tp can be determined. How-ever, the thicknesses calculated according Equations (6.1), (6.2), and (6.3) are unrealis-tically small due to the low cargo induced loads. As a result, the thicknesses of the threedecks are governed by the wheel loading of translifters (DNV-GL, 2017c).Table 6.3 shows all the thicknesses for the midship section, as well as their critical criteria.These results are all determined by the ballast condition which is the conservative casefor this ship.

Table 6.3: Plate thicknesses

Plate Location Plate thickness [mm] Governed by

Weather Deck 14.27 Wheel loadingMain Deck 14.27 Wheel loadingLowest Deck 14.27 Wheel loadingInside Side Wall 15.58 Local pressureOutside Side Wall(5m draft) 14.90 Local pressureOutside Double Bottom(5m draft) 14.70 Local pressureInside Double Bottom 15.80 Local pressure

6.2.3 Longitudinal Stiffeners

The longitudinal frames are the secondary stiffeners that support the shell plating withsmall and closely-spaced bulb flats. The spacing between them is constant at 700 mm.The bulb flats are considered the most cost-effective, efficient and corrosion-resistantsolution for plate stiffening requirements. The main advantages include an excellentstrength to weight ratio delivering buckling resistance at a lower weight than with flatbars or angles. The rounded edges of the bulb profile mean there is no need for edgegrinding prior to painting, saving time and money during fabrication. Paint degradationand the build up of corrosive debris is also reduced, extending life performance.The sizes of the longitudinal stiffeners are decided based on the local section modulus (Z)which is calculated according to the Equations (6.4) to (6.6) (Ringsberg & Thelandersson,2016).

Zrequired = Mmaxsection

σy(6.4)

Mmaxsection= 1

12QSf (6.5)

Zselected = Isds

(6.6)

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6 Structure

where: Zrequired is the required section modulus for the assembly of one longitudinalstiffener and the plate with 700 mm spacing,Mmaxsection

is the maximum bending momentcalculated according to Equation (6.5), Q is the equivalent total force on the assembly ofthe plate and the longitudinal stiffeners between one frame spacing, when Sf is the lengthof the frame spacing, Is is the moment of inertia which is calculated for the assembly,and ds is larger distance between the distance from the neutral axis to the plate or thetop of the stiffeners.The section modulus is smaller and so it will be the critical condition. Since the bulbflats are used as longitudinal stiffeners, an industry standard is used to choose the sizes(British Steel, 2017). The aim in choosing a specific bulb flat is to ensure that the selectedsection modulus (Zselected) is larger than the required (Zrequired).

Figure 6.4: Longitudinal stiffener properties

Table 6.4: The Longitudinal Stiffeners Size

Stiffeners LocationStiffener Size(b [mm] x t

[mm])Zrequired [m3] Zselected [m3]

Weather Deck 160 x 10 1.31 · 10−4 1.40 · 10−4

Main Deck 160 x 10 1.31 · 10−4 1.40 · 10−4

Lowest Deck 160 x 10 1.31 · 10−4 1.40 · 10−4

Inside Side Wall 230 x 11 3.42 · 10−4 3.54 · 10−4

Outside Side Wall (5m draft) 220 x 11 3.03 · 10−4 3.16 · 10−4

Outside Double Bottom (5m draft) 300 x 11 6.57 · 10−4 6.70 · 10−4

Inside Double Bottom 320 x 11.5 7.34 · 10−4 8.13 · 10−4

Figure 6.4 shows the properties of the bulb flats, and Table 6.4 shows the final choices oflongitudinal stiffeners sizes according to the required local section modulus.

6.2.4 Side Wall

According to the structural arrangement, two double side wall are installed from thedouble bottom to the main deck. The main deck is connected with the weather deck witha single side wall. The inside wall of the double wall works as a longitudinal bulkhead.Moreover, the double side walls decrease the span of the main deck and the bendingmoment on the main deck as well. The space between the double side walls is used for

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6 Structure

ballast and fuel tanks. The calculation procedures of the side wall plate thicknesses andthe longitudinal stiffeners follows the equations in Sections 6.2.2 and 6.2.3, respectively.The thicknesses are shown in Table 6.3.

6.2.5 Decks

For this project ship, there are three decks considered in the midship section: the weatherdeck, the main deck and the lower deck. The span of the weather deck is 32 m wide andthe span of the main and lower cargo deck is 24 m, due to the existence of the doubleside walls.

The main deck is close to the neutral axis of the midship section, and therefore, thebending moment that results from global strength on this deck is insignificant. Due tothe low cargo weight, the hogging condition is the critical condition for the ship structure.The weather and the lower deck have the biggest distances from the neutral axis. Thefirst will sustain high tensile stresses, while the later, high compressive stresses resultingfrom the global bending moment.

The plate thickness calculation procedures follow the equations which are described inthe Section 6.2.2. The size of the longitudinal stiffeners follow the Section 6.2.3. Thechosen thicknesses are shown in Table 6.3.

6.2.6 Double Bottom and Wing Tanks

The wing tanks are located at the sides of the vessel on top of the double bottom. Thedouble bottom and wing tanks can contribute to:

• the increase of the longitudinal and transverse strength,

• safety in case of damage/collision,

• ballast water storage–uneven loading/heeling/trim control, and

• fuel storage.

The double bottom height, is calculated from the Equation (6.7) (DNV-GL, 2017f).

HDB = 1000B2 (6.7)

This results in a double bottom height of 1.6 m. The double bottom extends from close tothe aft cargo hold bulkhead until the bulkhead that separates the engine and the thrusterroom, (Frame #45 to #222). The designed radius of the bilge is 2.0 m, matching thehydrodynamic design.

6.2.7 Longitudinal Girders

When calculating the strength of midship cross-section, no longitudinal girders are con-sidered since they do not contribute to the local strength, but only to the hull girderstrength. According to the ship’s design, there are no pillars in any of the cargo decks.Therefore, there is no place for longitudinal girders to attach. The only position that

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6 Structure

a longitudinal girder could be installed is the double bottom. However, it should bementioned that the inside side walls acts as longitudinal girders.

6.2.8 Web Frames

The web frames are placed on every third frame station and the spacing between themis constant at 2400 mm. The choice of this value was based on a reference ship.Considering the double bottom and the lower deck, the floors and the bilge plates areacting as web frames. The thickness of the floor is calculated according to Equation (6.8)(DNV-GL, 2017i).

tfloor = a+ bl2√k (6.8)

where: a and b are coefficients from the rules, l2 is the rule length of the ship (DNV-GL, 2017e) and k is the material factor provided by the classification society (DNV-GL,2017g).The thickness of the bilge support plate is calculated according to Equation 6.9 (DNV-GL,2017i).

tb = 6.45 · 10−4 · (PexSf )0.4R0.6 (6.9)

where: Pex is the pressure which is obtained from Nauticus Hull, Sf is the distancebetween the transverse stiffeners (2.4 m) and R is the effective bilge radius (2 m).T beams are used on the side walls, the weather and the main deck. The sizes of the webframes are calculated according to Equations (6.4), (6.5) and (6.6).Additionally, the thicknesses of the double bottom floor, the lower deck floor and thecurved bilge plate are expressed as tw. The resultant values are 7.36 mm, 7.36 mm and11.88 mm, respectively. Moreover, the results of the T beams are shown in Table 6.5.Figure 6.5 shows the T beam, the floor and the bilge plate properties in detail.

Table 6.5: Web frame size

Web Height Web Thickness Flange Length Flange Thicknesshw [mm] tw [mm] lf [mm] tf [mm]

Weather Deck 1000 20 400 35Main Deck 1000 10 250 30(Middle part)Main Deck 250 5 80 8(Side part)Inside Side Wall 1000 20 400 40Outside Side Wall(5m draft) 1000 20 400 40Upper Side Wall 600 10 200 10

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6 Structure

Figure 6.5: Web frames properties

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6 Structure

6.2.9 Cross Section Summary

Figure 6.6 shows the port side midship section with the web frame structures. Thestarboard side is symmetric to the port side. The names of all components are found inTable 6.6, while all sizes are found in Tables 6.3, 6.4 and 6.5. It should be noted thatsince the deck stiffeners are all the same, they are listed as the same component (8) inFigure 6.6 and Table 6.6.

Figure 6.6: Midship section of port side

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6 Structure

Table 6.6: Midship section component names

Number Name Number Name

1 Weather Deck 12 Outside Double Bottom Stiffener2 Main Deck 13 Weather Deck T Beam3 Lowest Deck 14 Main Deck T Beam (large)4 Inside Side Wall 15 Main Deck T Beam (small)5 Outside Side Wall 16 Inside Side Wall T Beam6 Outside Double Bottom 17 Outside Side Wall T Beam7 Inside Double Bottom 18 Upper Side Wall T Beam8 Deck Stiffener 19 Floor (double bottom)9 Inside Side Wall Stiffener 20 Floor (lowest deck)10 Outside Side Wall Stiffener 21 Bilge Plate

11 Inside Double BottomStiffener

6.3 Buckling

Generally, when a ship is under still water and navigation condition, it suffers globalbending moments that induce hogging and sagging. This results in tension and com-pression stresses throughout the hull girder. When the compression stresses exceed thepermitted stress, buckling will happen.In this project, the buckling analysis followed the calculation guidelines provided by theclassification society (DNV-GL, 2017j) and Marine Structure Engineering (Ringsberg &Thelandersson, 2016). Due to the low cargo weight for this ship, the buoyancy of the shipcreates a higher global bending moment than the cargo does. This results in a dominanthogging condition for the ship. Buckling is therefore most likely to occur in the doublebottom structures.

Figure 6.7: Longitudinally Stiffened Plate

Figure 6.7 shows a longitudinally stiffened plate similar to the structures found in the

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6 Structure

outer bottom of theM/S Big Buoy. In Figure 6.7, a is the distance between two transversegirders, b is the distance between longitudinal stiffeners, and R is the span of the plate.The buckling check for this ship focuses on the plates, longitudinal stiffeners, and thetransverse web frames.

6.3.1 Bottom Plates

The first step is to determine the Euler buckling stress σE according to Equation 6.10(Ringsberg & Thelandersson, 2016). The critical buckling stress σc is the maximum stressbefore buckling will occur and is calculated using Equations 6.11 and 6.12. Finally, thecritical buckling stress can be compared to the actual stress acted on the plates to checkif buckling happened on the plates.

σE = π2E

12(1− ν2) · (tpls

)2 · 4 (6.10)

In Equation (6.10), E is the young’s modulus, ν is the possion ratio, tp is the platethickness, and ls is the distance between longitudinal stiffeners.

σc = σE when σE <σy2 (6.11)

σc = σy(1−σy

4σE) when σE >

σy2 (6.12)

In Equation (6.11), σy is the yield stress for the plate.

6.3.2 Longitudinal Stiffeners

The Euler stress for lateral buckling of longitudinal stiffeners calculated according toEquation 6.13 (Ringsberg & Thelandersson, 2016), while critical buckling stress calculatedaccording to Equation 6.11 and 6.12.

σE = π2EIaAlS2

f

(6.13)

In Equation (6.13), Ia is the moment of inertia of the assembly cross section of the platewith 700mm width and one longitudinal stiffener, Al is the total area of the cross sectionof the plate and the longitudinal stiffener, and Sf is the distance between two transverseweb frame, which is a in Figure 6.7. Then the comparison procedure is similar with theprocedure in Section 6.3.1.

6.3.3 Transverse Beam

The transverse beam strength is controlled by Ib,req > b4

4sl3 · Ia, and if Ib < Ib,req. Thebuckling stress σE is calculated for the entire plate filed according to Equation 6.14(Ringsberg & Thelandersson, 2016).

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6 Structure

σE = π2E

AlS2f

· 2√lsS3

fIaIb

b4 (6.14)

In Equation (6.14), Ib is the moment of inertia of the assembly cross section of the platewith 2400mm width and one transverse beam. It should be noted that b is the span ofthe entire bottom plate. The critical buckling stress is calculated according to Equation6.11 and 6.12, and comparison procedure is similar with the procedure in Section 6.3.1.

6.3.4 Buckling Check Summary

Nauticus Hull provides the bending moment in hogging condition(Mhog), the moment ofinertia for the midship section(Imid) and the vertical distance from the baseline to theneutral axis(Zn). These values can be used for the calculation of the actual stresses,according to the Equation (6.2). These values for the ship under analysis are: Mhog =1.25 · 109 Nm, Imid = 259.15 m4 and Zn = 8.704 m.

Table 6.7 shows the buckling check results for the bottom structures, where dz is thedistance to the neutral axis. The results show that there is no risk of buckling for thestructural members at the double bottom.

Table 6.7: Buckling check summary

Component σc Mhog/Imid dz Actual Stress Results[Pa] [Pa/m] [m] [Pa]

Outside Bottom Plate 2.65 ·108 4.82·106 8.704 4.2·107 OKOutside BottomStiffener 3.47 ·108 4.82·106 8.704 4.2·107 OK

Outside BottomTransverse Beam 2.51 ·108 4.82·106 8.704 4.2·107 OK

Inside Bottom Plate 2.73 ·108 4.82·106 7.104 3.42·107 OKInside BottomStiffener 3.48 ·108 4.82·106 7.104 3.42·107 OK

Inside BottomTransverse Beam 2.56 ·108 4.82·106 7.104 3.42·107 OK

6.4 Finite Element (FE) Analysis

"The objective of the global strength analysis is to obtain a reliable description of theoverall hull girder stiffness and to calculate and assess the global stresses and deforma-tions of all primary hull members" (DNV-GL, 2016c). Consequently, the FE analysisis considered to be a crucial part of the structural analysis of the M/S Big Buoy. Theprimary goal is to obtain several results of the generated stresses and deformations of thevessel’s body under loading. Initially, the sizes of the structural members are obtainedby the hand-calculations performed in an earlier stage.

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6 Structure

The FE modelling of the cargo hold is made in Sensam GeniE (DNV-GL AS, 2016). Themembers included are the external hull plates, the longitudinal stiffeners, the web frames,the girders, the side wall, and the double bottom structure with its floor. There are somemembers that are not included in the analysis. Those members are notches, brackets andsnipped end connections. The reason is that they are considered to be structural detailsthat do not influence the FE analysis.

6.4.1 Cargo Hold Model

The section under analysis is the cargo hold. As can be seen in Figure 6.8, the total lengthof the ship is divided in 247 frames. The chosen area under investigation is betweenFrames 36 and 159 which has a total length of 98.4 m. This sufficiently representsthe actual cargo hold area of the buoys, being enough to provide the magnitude of thestructural stresses.

Figure 6.8: Ship’s part under FE analysis

According to DNV-GL instructions regarding the FE analysis, "Shell elements shall beused to represent plates and stiffeners shall be modelled with beam elements (...)" (DNV-GL, 2016c). The transverse web-frames, the floors, as well as the girders, are designedin GeniE as beam elements. The hull surface plates are designed in Nauticus Hull andthen imported in GeniE. During the FE analysis procedure, all members are modified inGeniE and later their results are plotted in Xtract (Ceetron AS, 2015).

All the element sizes, as plate thicknesses and stiffener sizes, are chosen to agree with thehand-calculations made in an earlier stage, so that a comparison between the resultantstresses and deformations acting on the ship’s structure can take place. The FE modelused for the analysis can be seen in Figure 6.9.

6.4.2 Boundary Conditions

"The cargo hold model shall be supported at the ends to provide constraint of the modeland support of the unbalanced forces." (DNV-GL, 2016c). Fixed boundary conditionsare set at the forward and aft ends of the midship under analysis. In both ends, severalsupports on all plate edges are generated, except the ones at the main deck. The boundaryconditions are highlighted in red colour in Figure 6.10.

As expected, the existence of fixed supports at both ends of the model generates highstress concentrations close to the boundary conditions. Consequently, the effects of theglobal bending of a fixed beam should be neglected.

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6 Structure

Figure 6.9: View of the FE model

Based on beam theory, a cross section free of global bending effects, should be at a distanceof 0.2113 and 0.5 of the FE model’s length. The 0.2113 LFE is where the global momentis zero and 0.5 LFE is where the shear forces become zero. As a result, all the plotsof the generated stresses include the area between 0.2113 LFE from the structure ends,neglecting the areas where the boundaries condition determine the resultant stresses.

Figure 6.10: Supports used in FE analysis

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6 Structure

6.4.3 Mesh

"The element mesh shall follow the stiffening system as far as practicable, and shallrepresent the actual plate panels between stiffeners, i.e. s·s, where s is the stiffenerspacing." (DNV-GL, 2016c). In order to choose the mesh size, a convergence investigationneeds to take place. The reason is that the mesh size should give sufficiently accurateresults but in the same time not be too expensive. The results of the convergence studyare shown in Table 6.10.

Table 6.8: Maximum generated stress for different mesh element sizes

Mesh size [m] Maximum von Mises stress [MPa] Simulation time [s]

2 287 9281 273 10170.8 266 11690.5 231 13420.4 229 1404

Keeping in mind the data in Table 6.10, it can be claimed that the mesh size of 0.5m gives adequately accurate results. In any case, according to the rules, the mesh sizeshould be no bigger than the spacing between stiffeners.In addition, the simulation time has insignificant differences between the different meshsizes. All the following presented results use 0.5 m as mesh element size. The meshedmodel can be seen in Figure 6.11.

6.4.4 Load Cases

"A FE load combination is defined as a loading pattern, a draft, a value of still waterbending and shear force, associated with a given dynamic loadcase." (DNV-GL, 2016c).Nauticus Hull allows the generation of several dynamic loadcases, as established by theDNV-GL rules (DNV-GL, 2017h). The chosen loadcase is BSR-1P (Bending StrengthRatio). It uses an "Equivalent Design Wave that minimises roll motion downward on theport side with waves from the port side" (DNV-GL, 2017h). The acting wave loads arehighlighted in orange in Figure (6.12).The buoyancy and wave loads that act on the hull external surfaces are exported fromNauticus Hull and imported to GeniE together with the plates that they act on. Addition-ally, the ship’s steel weight is included while solving the FE model in GeniE. Moreover,on the ship structure also acts the cargo load as well as the ballast water and fuel loads.The cargo load of the M/S Big Buoy can be approximated to be a surface pressure of 1ton/m2 acting on the decks. The ballast water and fuel tanks are in the double bottomand side walls.

6.4.5 Analysis Criteria

The criteria for analysing the results of the FE analysis are established in the rules(DNV-GL, 2016c). The criteria are used to determine the maximum acceptable level of

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6 Structure

Figure 6.11: The meshed model used for the FE analysis (zoom)

stress for each member of the structure arrangement. The maximum permissible stress isdetermined using the yield utilisation factor given in Equation 6.15. Table 6.9 summarisesthe permissible stresses for the structural members.

λy ≤ λyperm (6.15)

In Equation (6.15), λy is yield utilisation factor and λperm is the permissible yield utili-sation factor.

Table 6.9: Permissible coarse mesh yield utilisation factor λperm (DNV-GL, 2016c)

ElementType

StructuralMember

Permissibleyield utilisationfactor λperm

Permissible vonMises stress[N/mm2]

YieldUtilisationFactor

Definition

ShellHull plating,bulkheads,decks, floors

0.8 284 λy = σvm

Ry

BeamLongitudinals,deck beams,web frames

0.8 284 λy = σaxial

Ry

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Figure 6.12: The BSR-1P dynamic loadcase acting on the ship’s hull

6.4.6 Results and Discussion

The FE analysis provides values of several resultant stresses acting on the ship structure.In order to evaluate if these generated values are allowable, the von Mises stresses arecompared with the permissible stresses, according to Table 6.9. The maximum stressesacting on each structural member are compared, according to the most severe loadcase.Between the different loadcases, the most severe is proven to be loadcase A (Full load -No ballast). The maximum obtained von Mises stress is 231 MPa and is located on themiddle of the outer bottom shell.

The resultant von Mises stresses at the inner and outer bottom shell are shown in Figures6.16 and 6.15, respectively, with the colour bar limited from zero to 284 MPa (maximumpermissible von Mises stress). Regarding the inner bottom shell, the maximum stress is206 MPa and occurs at the loadcase B. That is expected, since there is no cargo load andthe plate is under a 10.1 m ballast water hydrostatic pressure. The maximum resultantstress on the outer bottom shell is 231 MPa and occurs at loadcase A. This is the highestrecorded stress in the ship’s structure.

In loadcase A (no ballast), the outer bottom shell is under the buoyancy pressure and soconsidering that the outer and inner side shells are connected, all the double bottom isin hogging condition.

In loadcase B (ballast), the outer bottom shell is under the pressure of both buoyancyand ballast water hydrostatic pressure. More specifically, the ballast water pressure islarger than the pressure from the buoyancy. However, the ballast water pressure is alsoacting on the inner bottom and the whole double bottom is in hogging condition, even

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Figure 6.13: 30x exaggerated global deformation for loadcase A

Figure 6.14: 30x exaggerated global deformation for loadcase B

with full ballast.The maximum stress for the outer side wall is 137 MPa and occurs in loadcase A. That

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is because during the no ballast condition, the outer side shell is under the sea waterpressure from outside while there is no load counteracting from the inside.Regarding the inner side wall, the maximum acting stress is 193 MPa and occurs inloadcase B. The existence of the ballast water in the side wall tank creates a pressureon the inner side wall and that explains the significant differences between the loadcasesat the stress plot of this plate. The outer and inner side wall von Mises stress plots areshown in Figures 6.17 and 6.18, respectively, with the colour bar limited from zero to 284MPa.The von Mises stresses of the main deck can be seen in Figure 6.19, where the colour baris limited from zero to 284 MPa. The main deck plate has some areas with high localisedstress. These are located at the intersection with the inner and outer side walls.The von Mises stress generated on the weather deck can be seen in Figure 6.20, wherethe colour bar is limited to 284 MPa. The maximum von Mises stress is 124 MPa and islocated at the intersection with the upper side shell. In the middle of the deck, there isalso an area of increased stress values.The stress on both the weather and main deck is determined by the cargo load. Therefore,the critical condition for both the weather and main deck is loadcase A.The generated stresses on the main and weather deck are low. That means that thechosen stiffeners are over-dimensioned. However, it can be claimed that the low resultantstresses are a result of the fact that the cargo load in the FE analysis is represented as asurface load. On the contrary, during the hand-calculations, the cargo load is representedas wheel load for the dimensioning of the stiffeners.The resultant von Mises stresses must be compared with their corresponding allowablestresses, as calculated in Table 6.9. The stresses on all the structural members are lowerthan the permissible ones. The most critical member is the outer bottom shell with anobtained stress value of 231 MPa for loadcase A. The maximum allowable stress is 284MPa, so the smallest safety factor of a structural member is 1.23. The safety factor inTable 6.9 is calculated as the ratio between the permissible and the acting maximumstress.

Table 6.10: Summary of the maximum von Mises stresses

Structural member Maximum acting stress[MPa]

Criticalloadcase Safety factor

Weather Deck 145 A 1.96Main Deck 167 A 1.7Outer bottom shell 231 A 1.23Inner bottom shell 206 B 1.38Outer side shell 137 A 2.07Inner side shell 193 B 1.47

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Figure 6.15: The von Mises stress plot for the outer bottom plate for loadcase A (upper)and loadcase B (upper)

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Figure 6.16: The von Mises stress plot for the inner bottom plate for loadcase A (upper)and loadcase B (upper)

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Figure 6.17: The von Mises stress plot for the outer side wall for loadcase A (upper) andloadcase B (lower)

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Figure 6.18: The von Mises stress plot for the inner side wall for loadcase A (upper) andloadcase B (lower)

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Figure 6.19: The von Mises stress plot for the main deck for loadcase A (upper) andloadcase B (upper)

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Figure 6.20: The von Mises stress plot for the weather deck for loadcase A (upper) andloadcase B (upper)

84

7 MachineryThe following chapter details the design of the propulsion system of the ship and theselection of the major components in the engine room. It culminating in the optimisationof the engine configuration.

Following the design of the hull with minimal resistance, the machinery systems can bedesigned to ensure the ship reaches its design speed with minimum fuel consumptionand exhaust emission rate. To this end, the first design step is the consideration ofthe appropriate fuel types, which was chosen to be methanol. Two main engines andtwo auxiliary engines have been chosen. Currently a conversion kit was installed on theengines to operate on methanol, however it is expected that engines in full methanolversion will be available on the market soon. The engines are incorporated in sucha way that a hybrid methanol electric system can be used for effective functioning ofthe engine. The exhaust system concentrates on maximising the energy regain. Thewaste heat recovery system includes a common boiler economiser, a power turbine andan technology based on the ORC for efficient regain for the remaining of heat. This isfollowed by selection of sub machinery systems such as the sewage treatment plant, thefreshwater generator and the ballast treatment plant.

The final objective of all this was to achieve the design of the engine room drawing,as can be seen in Appendix B. The propulsion system of the vessel has been designedwith the main objective of incorporating efficient and sustainable technologies as well asfor future consideration design a system set-up flexible to incorporate the changes beingmade over the years. Keeping that in mind, future work that can be done with regardsto the machinery system can be seen in the Chapters 8 and 9.

7.1 Rules and Regulations

Emission Control Areas (ECAs) are areas where the emission regulations are stricterregulations than in open sea, are established by MARPOL Annex VI to restrict theairborne emissions of NOx, SOx and particulate matter. These regulations stem fromconcerns about the contribution of the shipping industry to local and global air pollutionand environmental problems. Figure 7.1 shows the currently established as well as thefuture ECAs in the world.

The North Sea area under the Emission Control Areas is designated under regulation14.3.1 of MARPOL Annex VI and Regulation 1.14.6 of MARPOL Annex V (Pablo Semoli-nos & Giacosa, 2013). The boundary encompassed by this area is between:

1. The North Sea southwards of latitude 62◦N and eastwards of longitude 4◦W,

2. The Skagerrak, the southern limit of which is determined wast of the Skaw bylatitude 57◦44.8’N, and

3. The English Channel and its approaches eastwards of longitude 5◦Wand northwardsof latitude 48◦30’N.

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Figure 7.1: Estimated ECA in future (GREEN4SEA, 2017)

Table 7.1: SOx limits inside and outside Emission Control Areas (ECA) (IMO, 2017)

Limits of SOx particulate matteremissions outside ECA

Limits of SOx particulate emissionsinside ECA

4.50% m/m prior to 1January 2012 1.50% m/m prior to 1 July 20103.50% m/m on and after 1 January 2012 1.00 % m/m on and after 1 July 20100.50% m/m on and after 1 January 20201 0.10% m/m on and after 1 January 2015

1 Depending on the outcome of a review to be concluded by 2018, as to the availabilityof required fuel oil, this date could be deferred to 1 January 2025.

Table 7.1 encompasses the SOx and particulate matter limits as set by MARPOL underRegulation 14. This area is also the operating area of the vessel.

Table 7.2: NOx emission limits (IMO, 2017)

Tier Date NOx Limits [g/kWh]n < 130 130 ≤ n ≤ 2000 n ≥ 2000

Tier I 2000 17.0 45·n−0.2 9.8Tier II 2011 14.4 44·n−0.23 7.7Tier III 2016 3.4 9·n−0.2 1.96

Table 7.2 shows the NOx emission restrictions on marine diesel engines. Tier II to befollowed in areas outside ECA. Tier III requirements would apply to installed marinediesel engines when operated in other emission control areas which might be designatedin the future for Tier III NOx control. Tier III applies to ships constructed on or after thedate of adoption by the Marine Environment Protection Committee of such an emission

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control area, or a later date as may be specified in the amendment designating the NOx

Tier III emission control area.While the MARPOL does not have restrictions on NOx emissions in the North Seacurrently, it is essential to consider the emission limits of both NOx and SOx as thegoal is to have minimum emissions for the benefit of the environment. In foresight it isgood to have a system with low NOx emissions since beginning from January 1 2021 theNorth Sea will be designated as a NOx Emission Control Area (NECA).The idea of building an environmentally friendly ship stems from Waves4Power ’s strongbeliefs in sustainability. The company is committed to providing a sustainable source ofenergy to the electrical grid with the means of its buoys, and therefore, it follows thatthe vessel carrying the buoys should be a vessel with little to no harmful emissions. It isthis commitment and belief of the company in sustainable practices that motivates thebuilding of the vessel.Figure 7.1 shows that future ECAs are likely to be established along the Norwegian coastwhich includes the loading port of the buoys. It is good to build a ship that can be runin the future as well without any major changes to the propulsion systems. Over theoperational life of the ship some minor changes may be made to the propulsion systembut in general it should be capable of meeting the increased emission restrictions of thefuture.

7.2 Comparison of Fuel Types

Three alternatives to the conventional Heavy Fuel Oil (HFO) were considered for theship: Marine Gas Oil (MGO), Methanol and Liquefied Natural Gas (LNG). The primaryreason for switching to an alternative fuel is to reduce the emissions from the ship whichcontribute to air pollution in many port cities. Burning of traditional bunker oil inships results in heavy emissions of sulphur oxides and particulate matter. While HFOis cheap and has a stronghold in terms of fuel usage, it is because of its usage all overthe maritime industry that the industry accounts for 8% of global emissions of sulphurdioxide. This makes the industry an large source of pollutants that contribute to acidrain and respiratory diseases (Molloy, 2016).Table 7.3 shows a brief comparison of the typical marine fuels used and considered for thepropulsion of the vessel. It is worth mentioning that hydrogen was initially consideredas an alternative as well, but it was ruled out from a detailed analysis because of thecurrent state of the technology and storage of hydrogen. It is not feasible to have fuel cellsrunning on hydrogen powering a large cargo carrier since the maximum power output ofa fuel cell system today is much smaller than the power required to propel the vessel.This would result in a need to install several small systems which while possible wouldbe very costly. Additionally, storage of hydrogen needs large, heavy tanks which aredifficult to place on the vessel given that the cargo occupies most of the space on thedecks. Therefore, hydrogen was not included in any of the further analysis.A more detailed analysis of each of the comparison parameters is made below. The focusis given to methanol and LNG as they are the alternative fuels.

1. Calorific Value: It is the amount of heat released during the combustion of a speci-fied amount of it. For fuels, generally the comparison is done considering the Lower

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Table 7.3: Comparison of marine fuels (DNV-GL, 2017a)

HFO MGO Methanol LNG

Calorific Value[kJ/kg] 41 45 23 43 [kJ/m3]

Flash Point [oC] 60 >60 11.1 -180Energy Density[MJ/L] 37.3 35.9 15.6 22.2

Density [kg/m3] 1010 <900 803 410-500

Source Petroleum Petroleum Natural Gasand Biomass

Natural and BioGas

Storage Issues

Corrosion issuesdue to high

sulphur contentin the fuel

No specialstorage issue

HighlyFlammable and

toxic

LNG is storedin cryogenictanks at highpressure andtemperature

EnvironmentalImpact

High sulphurdioxideemissions

Sulphuremissions muchless than HFO

Clean Fuel withonly CO2 as the

unwantedproduct

Clean fuel andlike methanolonly emitsCO2on

combustion

Availability Easily Available Easily AvailableMay needadditional

infrastructure

May needadditional

infrastructure

Heating Value (LHV) of the fuel (The Engineering Toolbox, 2017b). It can beconcluded from Table 7.3 that for each Kilogram of fuel consumed, HFO gives themore energy while methanol the least.

2. Flash Point: It is the temperature at which the vapours of a material ignite. Notto be confused with auto-ignition temperature, it is understood that the ignitionsource temperature is higher than the flash point(The Engineering Toolbox, 2017a).LNG has a very low flash point and due to this its storage is highly specialised sinceit involves keeping a constant low temperature for LNG. Due to the nature of thecargo on the vessel,having a large specialised storage system while still feasible willnot be economical. Methanol on the other hand does not require such specialisedstorage.

3. Energy Density: It is the amount of energy stored in the fuel per unit volume(Haynes, 2015). It can be seen from Table 7.3 that methanol has the smallestenergy density which means that in order to fulfil the energy requirement of thevessel, slightly less than twice the weight and slightly more than twice the volumeis needed. While the energy density of LNG is approximately 61% of MGO makingit more efficient economically over a long distance transport, its storage would needspecialised cryogenic tanks which would add to the weight and volume of the fuelneeded for the vessel.

4. Source: A major aspect to consider before choosing the fuel to be used is the sourceof the fuel. It is preferred that the fuel is produced from a renewable source of

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energy instead of the fast depleting fossil fuels. Both Methanol and LNG can bemanufactured from feedstock and from fossil fuel resources. In this scenario, it ispreferred that the source of the fuel selected is renewable.

5. Storage Issues: Analysing the storage issues of fuels is another major aspect whichshould be considered before choosing the fuel. While there will be no fuel whichhas no storage issues, some compromise can be made if the fuel has many other ad-vantages. Storing methanol needs care as it is a toxic and flammable fuel. Howevercompared to storage of LNG, it does not need large and heavy specialised storagetanks. Methanol can be stored in more traditional storage tanks or in tanks whichare along the hull. The same cannot be said for LNG as it will not be very feasibleto store it in hull tanks since maintaining constant temperature and pressure isessential for storage of LNG. For the ship in concern, it is easier to store methanolthan LNG

6. Environmental Impact: Another very important criteria while selecting the fuel fora ship is its impact on the environment. Shipping is a large global industry andcan thus play a very important in the move towards sustainability of environment.Fuels producing sulphur and nitrogen oxides are being shunned as the populationdemands cleaner and greener alternatives. Combustion of methane and LNG doesnot emit SOx and can reduce NOx compared to traditional fuels thus reducing theirpresence in the environment.

7. Availability: A conventional fuel is often chosen over alternative since it is cheaperand readily available due to an existing established infrastructure. From the designproject’s point of view, availability of bunkering facilities is one of the most impor-tant factors because, if the alternative fuel is selected but cannot be made availablethen the vessel will have to be run on conventional fuels. For this vessel, MGO isconsidered as an optional fuel in case Methanol or LNG cannot be made availableto the port.

Based on the comparison made above it can be concluded that methanol is a very strongcontender as an alternative fuel choice compared to traditional fuels such as HFO. MGOcan be used as a secondary alternative if methanol from a environmentally friendly sourcecannot be made available.

7.3 Feasibility of Different Fuel Systems

The mission of the operation to aim for greener energy and less pollution, hence the chosenfuel type plays an important role in the vessel’s life. However not only the particularsof the fuel type should be considered in the selection process, but the overall machinerysetup, the added marketing values, prices, and availability should also be considered whenchoosing a specific type of fuel.

7.3.1 LNG System

A major advantage of LNG is that the engines need less maintenance since gas combustionis significantly cleaner process than the combustion of HFO or MGO (Pablo Semolinos &Giacosa, 2013). This results in significant savings for the ship owner. The price of LNG

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in recent years has been largely dependent on the price of the crude oil. In Figure 7.2a price comparison of different marine fuels (obtained from fossil fuels), including LNG,methanol and HFO is shown.

Figure 7.2: Comparison of Marine Fuel Prices (Ellis, 2017).

However, LNG has also some drawbacks. Its energy density based on kW/m3, as seenin Table 7.3 is much lower than that of traditional fuels, so the space occupied by thetanks is considerably higher. The overall volume occupied by all LNG facilities on-boardis between 3 and 4 times larger than for conventional fuels depending on the tank system.Although, at this stage there are ongoing researches to develop new storing technologiessuch as membrane tank, to reduce the volume required for storing LNG on-board.When considering the whole machinery setup, LNG machinery is more expensive thanstandard heavy fuel oil machinery equipped with sulphur scrubbers, but the LNG fuelprice can compensate for this. Due to safety reasons, there has been also discussion abouta regulation to limit the LNG fuel storage capacity of ships (Aarnio, 2015). Finally, thesafety aspects of LNG increase complexity of the supply chain, ship design and operationsand it requires more skilled and trained crew (Pablo Semolinos & Giacosa, 2013).

7.3.2 Methanol System

The emission reduction performance will be more prominent during the production ofthe methanol with either biomass or natural gas. The overall CO2 footprint, comparedto conventional fuel such as MGO (DNV-GL, 2016a). Furthermore, combustion of bio-methanol is considered to have lower green house gas emissions than other fuels since theCO2 produce is considered to be climate neutral, since it has the lowest carbon to CO2conversion factor (IMO, 2014).SOx emissions are negligible since methanol has a very low sulphur content. The measure-ments of researches indicate that NOx emission could be reduced dramatically, depending

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on the chosen methanol combustion concept, either Tier II or Tier III could be reached(DNV-GL, 2016a). It is assumed that NOx emissions during combustion are reduced byapproximately 60% when running on methanol compared to HFO, nevertheless furtherSelective Catalytic Reactor exhaust system can be installed on-board in contrary to LNGfuel in order to comply with Tier III limits (DNV-GL, 2016a). Overall, methanol fromrenewable feedstock is the greenest energy source for marine installation when comparedto LNG or MGO.Some noteworthy disadvantages of methanol are its toxicity and low flash-point whenbunkering (DNV-GL, 2016a). These can present issues in the handling and duringcombustion operations. These should be taken into consideration when implementinga methanol fuel system.

7.3.2.1 System Configuration

Due to its low flash-point, the configuration of the methanol system needs to comply withstrict rules and regulation such as the International Code of Safety for Ships using Gasesor other Low-flashpoint Fuels (IGF Code) to minimise the risk to the ship its crew andthe environment contrary to the configuration of conventional fuel systems (DNV-GL,2016a). The overall functional requirement is the safety, reliability and dependability ofthe systems shall be equivalent to that achieved with new and comparable conventionaloil-fueled main and auxiliary machinery. This level of safety is found by conducting a riskassessment, hazard identification analyses of the overall system that includes (DNV-GL,2016a):

• Bunkering of methanol,• Storage of methanol on-board,• Methanol handling and processing towards the main engine,• Combustion of methanol in the main engine, and• Methanol handling and processing after the main engine.

The overall methanol fuel system can be seen in Figure 7.3.The different safety requirements and concerns for each of the methanol fuel sub-systemcan be found in IGF Code as well as in DNV-GL rules and regulations (DNV-GL, 2016a).

7.3.2.2 Encouraging the use of Methanol

The relevance of methanol as marine fuel as a clear alternative in order to satisfy regu-lations can be seen in Table 7.4.The bio methanol is a measure which reduces CO2 emissions significantly, whereas LNGonly to a certain extent can reduce CO2 emissions and scrubbers do not have an CO2reduction effect at all. In addition, methanol reduces SOx and particles similar as LNG,and depending on the combustion process will to reduce NOx, to Tier II or Tier III.Methanol produced with natural gas does not reduce CO2 emissions from a life-cycleperspective, but it could be considered a CO2 measure in that methanol as fuel has thepotential to be created from biomass, as opposed to conventional fuels and LNG, whichare fossil-based by definition. Further, MGO can in principle be replaced with syntheticdiesel such as Hydro-treated Vegetable Oil (HVO), which is produced from renewable feedstock as well, but since the feed stock is limited there will not be enough synthetic diesel

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Figure 7.3: Methanol Fuel System (DNV-GL, 2016a)

Table 7.4: Emission relevance and the corresponding regulations (DNV-GL, 2016a)

EmissionType CO2 SOx NOx

Relevantregulatoryregime

EEDI SECAsNECAs (NOx

Tier-III)

Current experienceindicates that methanol

increases energyefficiency with a few

percentage points. Thiswould have to be

documented further inorder to be applicable in

EEDI

Measurementsindicate that

methanol may reduceNOx emissionssignificantly

Methanol’srelevance torequirements

EEDI takes intoconsideration the

methanol fuel type withbeing the lowest CO2

emissions factor, (Cf ) of1.375 for fossil basedand even lower for

bio-methanol

Methanolpropulsion

satisfies SECArequirements ofmaximum 0.1 %sulphur in fuels

Further tests mayshow that methanolcan be combined

technologies, such asexhaust gas

re-circulation (EGR),in order to bringemissions down to

tier-III

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available to replace conventional fuel. Methane be extracted from bio-gas production andliquefied into Liquefied Bio Gas (LBG) as an alternative to fossil LNG.From a regulatory point of view IMO is working on guidelines and regulations concerningmethanol vessels. With these upcoming regulations methanol is not considered to bemore dangerous than the common marine fuels.Overall, the methanol does have a certain potential to become a competitive marine fuel,even though the current interest to invest in methanol propulsion is rather vague. Thefuture price development of methanol is considered to be favourable compared to estab-lished marine fuels. The main drawback for restricting the use of methanol aboard vesselsis the limited established logistics for supplying the vessels with fuel on the operationalarea.In order to significantly reduce green house gas emission from shipping operation, renew-able produced methanol is one of few feasible alternatives, thus the following sections ofthe machinery system as well as engines will be set up in a way to operate on methanol.

7.4 Engine Load Calculation

The engine load calculation is an iterative design process including multiple rounds ofclarification towards a more accurate power requirement on-board of the vessel. The mostimportant thing in the design of the machinery system is to set up and understand thedifferent loading and power requirements for each of the operational conditions. Primarilythis is done estimating the propulsion power based on the main dimensions of the vesseland accounting for different efficiency losses as can be seen in Figure 7.4. Further, to therequired propulsion power, similar sized vessels were looked at to estimate the additionalon-board/vessel loads required to be covered.As for preliminary engine selection the initial power requirements were defined and canbe seen in Figure 7.5 as well as in Table 7.5.

Table 7.5: Initial power demand

Operation Propulsion [MW]+ 15%

Vessel Load [MW]+ 15%

Port/Anchor 0 1.725Port Manoeuvring 3.45 1.725OW Course Keeping 7.5 1.725Loading/Unloading 5.2 1.725Max Load 9.3 MW

A second level iteration can be made, after having obtained the actual required deliveredpower (PD=4395 kW), that already takes into account the propeller efficiency as seen inTable 5.1, Section 5.1.Accounting for a 10% electric transmission loss, as explained in Figure 7.6, the neces-sary break power at the engine flange can be calculated (MAN, 2015a) (Ådnanes, 2010).Furthermore the actual propulsion power and additional vessel loads on-board can be

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Figure 7.4: Energy balance consideration (ABB, 2017)

Figure 7.5: Operational profile

calculated adding the power demands of the necessary machinery sub-systems. Each ofthe different equipment were gathered and listed in a specific SFI Coding and Classifica-tion System, hence a more accurate and detailed power demand could be made for eachof the operational conditions as seen in Appendix A.

A brief summary of the second level iteration of the power demand can be seen in Table7.6.

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Figure 7.6: Electrical Transmission Heat Loss (MAN, 2015a)

Table 7.6: 2nd Level power demand

Operation Propulsion [MW]+ 15%

Vessel Load [MW]+ 15%

Port/Anchor 0 0.71Port Manoeuvring 3.22 1.95OW Course Keeping 6.5 2.42Loading/Unloading 3.45 4.1Max Load 8.9 MW

Comparing Table 7.5 and Table 7.6, it can be seen that the initial maximum powerestimate as well as the secondary one, are considerably close to each other. However, itshould be noted, theses numbers during a detailed design of the vessel, as such a 3rd, 4th

level iteration would be carried out and the power demand would be rectified even more.

7.5 Power Plant

Having determined the energy source to be used as well as the approximated total loadsthe machinery system can be developed. The vessel will be made ready for methanoloperation, however due to the current availability of methanol around the cruising area,the vessel needs to be designed to run on MGO as well. To this end, medium speeddual-fuel engines will be considered. When choosing the power and number of engines,rules and regulations as well as flexibility should be taken into account.

Based on the general arrangement, as seen in Appendix B, the cargo holds occupy themajority of the space, and the engine room is positioned in the front section of the vessel.Applying a conventional propulsion system, which would require installing a direct shaftdrive throughout the whole vessel would not be feasible, since a long shaft is not favourablein a structural and spacing point of view. Furthermore, installing Azipods would alsooffer a good course keeping with dynamic positioning, during unloading the buoys.

To this end, the chosen propulsion system is a more favourable methanol-electric system.The basic components of this are the gen-sets, the transformers, the electric motors

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and the loads that need to be covered. Such loads within the system include electricmotor driven propulsion pods, two bow thrusters, and the cargo handling as well as theon-board accommodation loads. Figure 7.7 gives a typical arrangement of a methanol-electric propulsion system.

Figure 7.7: Methanol-electric system arrangement (ABB, 2009)

This particular system can be coupled with multiple azimuth thrusters due to the in-creased power provided. Furthermore, the redundancy is increased leading to highersafety and flexibility to operate only the number of engines required in each operationalprofile and running on 70-90% Maximum Continuous Rating (MCR), hence reducing thefuel consumption. On the other hand the overall installation costs are slightly higher fora methanol-electric system.

7.5.1 Main Engines

At this current time there are no engines particularly developed and produced for onlymethanol. However Wärtsilä developed a technology for burning methanol, as a resultthey offer a retrofit package for existing engines to use methanol. The first ship wherea retrofitted engine operates is the Stena Germanica. A new common rail system wasfitted to two Sulzer ZA40S engines for methanol injection purposes, as seen in Figure 7.8and Figure 7.9, respectivelyIn addition to the on-engine conversion parts, the conversion kit includes: "stand-alonemethanol pumps", "stand-alone oil units" for supply of sealing and control oil to the fuel

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Figure 7.8: Retrofitted common rail system for methanol (Stojcevski, 2015)

Figure 7.9: Retrofit Solution on Engine Piping (Stojcevski, 2015)

injectors, and an update of the automation system (Stojcevski, 2015).Retrofitted diesel main engines are installed to cover the overall required power for propul-sion purposes, whereas auxiliary engines are installed to cover the additional on-boardloads, as seen in Table 7.6.During engine selections different safety requirements such as redundancy were consid-ered, and also an economical 75% MCR operational point was taken into account. Sub-sequently it was concluded that a minimum of 2 separate main engines of approximately5 MW each, should be covering the open water operation.Subject to availability of the retrofit package for the different Wärtsilä engines, two gen-sets of the new generation, more efficient 31D medium speed engine from Wärtsilä werechosen. Due to the current lack of availability of bunkering and fuel possibilities these

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retrofitted engines will be also able to operate on MGO in addition to methanol.

The 31D type is available in 8 to 16 cylinder configurations and have a power outputranging from 4.2 to 9.8 MW at 720 and 750 rpm, respectively. Furthermore, the engineis fully compliant with IMO Tier III when operating on methanol with an installed SCRin the exhaust ducts (Wärtsilä, 2017c). Based on the available rated powers for the 31D,the chosen configuration is 10V, where the available total maximum power is around 5.7MW at 720 rpm as seen in Table 7.7. Two of these will cover the required propulsionpower.

Table 7.7: Rated powers of 31D gensets at 100% MCR (Wärtsilä, 2017d)

Engine Type 60 Hz @720 rpm 50 Hz @750 rpmEng. [kW] Gen. [kW] Eng. [kW] Gen. [kW]

10V31 5 900 5 665 6 100 5 855

For space reservation in general arrangment, the overall dimensions of the 31D10V gen-setthat includes maintenance space as well, can be seen in Table 7.8.

Table 7.8: Overall space requirements for 31D10V gensets

Installation space reserve

Length 11.2 mWidth 3.8 mHeight 5.6 m

Overall Volume 224.8 m3

7.5.2 Auxiliary Engines

In addition to the main engines, to cover the remaining power in order to amount forthe maximum required load, as seen in Table 7.6 auxiliary engines are installed. Duringthe design of the auxiliary engine set-up, two options were considered, such as installingonly one single engine or two additional engines. However, for redundancy and flexibilityreasons the final set-up includes two auxiliary engines from the 20D series of the mediumspeed Wärtsilä engines. The size of the engines were chosen, based on providing thenecessary power on a 75% MCR economical operational point, as well.

Based on the available rated powers for the 20D series, the chosen configuration is 6L,where the available total maximum power is 2.2 MW at 1000 rpm as seen in Table 7.9.

For space reservation in the genreal arrangement, the overall dimensions of the 20D6Lgen-set that includes maintenance space as well, can be seen in Table 7.10.

A summary of the engine setup under current consideration can be seen in Table 7.11.

This setup results in a power supply of approximatley 13.68 MW with a reasonableflexibility.

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Table 7.9: Rated powers of 20D gensets at 100% MCR (Wärtsilä, 2017c)

Engine Type 60 Hz @720 rpm 50 Hz @750 rpmEng. [kW] Gen. [kW] Eng. [kW] Gen. [kW]

6L20 1110 1055 1200 1140

Table 7.10: Overall space requirements for 20D6L gensets

Installation space reserve

Length 6.09 mWidth 2.38 mHeight 3.25 m

Overall Volume 47.1 m3

Table 7.11: Summary of different engine setups

[Unit] Main-Genset Aux-Genset

Type W 10V31D W 6L20DNumber 2 2Length m 11.2 6.09Width m 3.6 2.4Height m 5.6 3.3Volume m3 224.8 47.1

Revolution rpm 720 1000Power MW 5.7 1.14

Total Power MW 11.4 2.28

7.5.3 Emergency Generator

In addition one extra gensets are included for emergency/ standby purpose, which islocated on an upper deck. This standby generators will only take up load in case theworking generators are out of order. The standby generators are not included in theabove calculation, but it is taken as 760 kW total output in this design stage. As per one20D4L engine with the properties seen in Table 7. At a later stage the actual emergencynecessary load will be carefully taken into account and the necessary gen-set can bechosen accordingly.

7.5.4 Hybrid System Consideration

The current technology that Wärtsilä offers is an integrated hybrid power module thatcombines the engines on-board and batteries optimised to efficiently work together throughan energy management system. This modular system is called Wärtsilä HY2 (Wärtsilä,

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2017f).

The sizing of the hybrid system is not only based on the maximum power demand ofthe ship, but also on its specific operational profile to aim for an economical and efficientrunning of the engines under different conditions. Integrating a hybrid system on-board asan extra means of power would give advantages such as smokeless operation, cold systemstart-up, instant load taking, automatic power back-up, start & stop, power boost andpeak shaving (Wärtsilä, 2017f).

The different power ranges for an overall battery pack system from Wärtsilä varies asseen in Figure 7.10.

Figure 7.10: Power range for Wärtsilä HY2 (Wärtsilä, 2017f)

The main purpose of installing such system on-board is to reduce the engine transient loadvariations, in other words, peak shaving purposes when the vessel is sailing or dynamicpositioning. Thus, it allows the engine to run at its most efficient load. This providesa more stable and efficient system with less dynamic effects. In addition, the installedsize of the battery pack should be able to power alone the vessel and provide enoughelectricity when anchored in harbour, where is a lack of shore electricity. To this endthe size of the battery pack was decided to cover 1 MWh. Primarily considering theon-board loads when the vessel is anchored in port. This size of battery pack with thecurrent technology is already available. Corvus Energy provides energy storage systemsto the Scandlines’ feet ranging from 1 MWh to 2.6 MWh (Corvus Energy, 2015).

Based on current availability from Corvus Energy, this 1 MWh battery storage modulecan be built up from 6.7 kWh capacity individual modules and could be placed on-boardas a separate dock-able units as well in 20 feet container or installed within the vessel ina separate room (Corvus Energy, 2015). This would mean 150 individual units with aweight of 72 kg and dimensions of 59x33x38 cm each (Corvus Energy, 2016).

A schematic of the hybrid system can be seen in Figure 7.11.

Furthermore if re-sizing of the battery storage units would be necessary there are certainthings need to be considered. At the current stage, hybrid system and battery storage

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Figure 7.11: Diesel-Electrical Hybrid System (Wärtsilä, 2017f)

units still require rather higher financial investments, and mean further technical chal-lenges, and more limitation in terms of safety regulations. One of the most prominentquestion is the future purpose of the hybrid system.

Each of the operational profiles of the vessel need to be considered more thoroughly in linewith the actual running engines. When looking at the most severe engine load variationwhen unloading in order to save fuel the size of the battery pack should be enough toconstantly cover the load variation during the actual unloading time, for peak shavings.This potentially would mean a smaller storage unit but a well-designed control systemand a good understanding of the total efficiency of the engines on-board in the currentvariable load operation.

In case the storage unit is increased and designed to cover individually the on-boardloads if the port facilities does not allow shore electricity, this would require a rather highdegree of energy availability from the battery storage unite.

In both cases also, the key element, is the control algorithms of the management systemthat determines how to share the load between units. To this end, the bigger the batterypack the better the power management and the hybrid system control unit should be toefficiently harvest the green technology.

Nevertheless, the actual invested budget should be compared to the turn over time andthe money saved on fuel, based on running the engines at an efficient point under one ormultiple loading conditions. Burning less fuel would also mean reduced amount of NOx

tax.

A comparison can be seen in Table 7.12 between the energy density of different fueltypes and the currently technically available batteries on the market, in terms of reservedweight and volume for the same amount of power.

It also should be noted, the actual mechanical energy that could be obtained, taking intoconsideration the transmission losses as well. A battery system is more favourable withonly a 10% transmission loss (MAN, 2015a). Nevertheless, with the upcoming technical

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Table 7.12: Weight and Volume reserve of different means for power production

Battery MGO Methanol LNG

Power [MWh] 1Weight [kg] 10800 173 224 153Volume [m3] 11 0.2 0.28 0.34

possibilities the industry is aiming to achieve stronger and cheaper batteries.

7.5.5 Feasibility Study of Main Engine Room Configuration

When selecting the engine configuration, the space reservations in the general arrange-ment must be checked for the final engine setup. The volume of space available waschecked against the volumes required for the engines. Furthermore, the available deckspace and heights in the engine room was checked to ensure there would be sufficientspace for both the engines and gensets and to properly manoeuvre around them formaintenance purposes.

When considering the volume of the spaces available, both configurations (1 or 2 auxiliaryengines) were considered and nearly take up the same space and both fit within theavailable reserved volume. The available space is four times that of the required spaces.This is a good indication that there should be adequate space in the main engine roomsto house either configuration of engines. The arrangements of the machinery systemcompared to the available space can be seen in Figure 7.12 and Figure 7.13 and a detailedmachinery room arrangement in Appendix B.

Figure 7.12: Machinery layout on Deck 1

In terms of height, the available total deck clearance in the engine room is roughly 10 m,which is divided by platforms. The maximum required height of the engines and gensetsin questions, is approximately 4.61 m for the main engine. This should fit well withinthe main engine room and leave approximately plenty of clearance head-space above theengine in which the piping to other systems and the exhaust can be run. This 10 m

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Figure 7.13: Machinery layout on Deck 2

already takes into account the height reserved for structural web frames and deck beamsas well.

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7.6 Propulsors

7.6.1 Azipods

As mentioned in Section 7.5, due to the required cargo place the engines will be installedin the for part of the vessel and because of the limitation to place shaft on-board throughthe cargo hold a methanol electric system is favourable. This machinery system canbe coupled with multiple azimuth thrusters to achieve better propulsion characteristics.Furthermore it would result neglecting the rudder, propeller shaft and brackets and offerbetter manoeuvring qualities that would be required when unloading the buoys to achievedynamic anchoring and positioning with azimuth system.In order to meet the operational profile of the ship, the propulsion system must be ableto operate efficiently while loading and unloading the cargo in a dynamic positioningmode. The available spacing inside and outside at the stern part of the hull provides anadequate clearance to install the CO series from ABB (ABB, 2015).Given the required power for the propulsion, the model unit can be chosen based in Figure7.14.

Figure 7.14: Different model units, power vs. propeller speed (ABB, 2015)

Based on the power range an Azipod unit with the model number of CO1400 was chosenfor its low weight and low power consumption. Taking into consideration the calculatedinput values from Section 5, it can be concluded that the delivered power for each of thepropeller and the their rpm fall within the range of the initially chosen model unit, asseen in Figure 7.14.

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7.6.2 Bow Thruster

For manoeuvring purposes bow thrusters, as shown in Figure 7.15 would give significantbenefit to position the vessel when unloading the buoys.

Figure 7.15: Tunnel Thruster (Sinha, 2017)

Reference offshore vessels with approximately the same main dimensions were looked intoto estimate the bow thruster power for the vessel. Most of the reference vessels variedbetween having 1-2 thrusters on-board with the total power ranging between 1.6 - 3 MW.

Location of the bow thruster tunnel is hydrodynamically important but it is also limiteddue to practical considerations. For example, for safety requirements it must be locatedbehind the collision bulkhead, but it should be as forward as possible to gain body-turningmoment as high as possible. However, it is also recommended that the thruster shouldnot be placed further forward than 0.1L from the forward most end (Chakrabarty, 2017).In addition to location, the diameter of the tunnel is very important. It is said thatthe tunnel diameter should be as small as possible to minimise the mounting space andincrease hull efficiency.

The vessel currently under design must have good positioning when unloading the cargoin severe environmental circumstances. To this end, it was decided to use two Rolls-Royce tunnel thrusters with diameter 2000 mm, length 2100 mm, shaft length 1620 mm.These have with an electric motor, rated at 1-1.3 MW, which provides total power ofmaximum approximately 2.6 MW. An estimation of the size of the motor used to powerthe propeller has been made. The electric motor driving the thrusters are approximatelysame height as shaft length and width is one third of the diameter of the thruster. Areaneeded for the thruster inside of the hull is approximately 700x700x1620 mm.

7.7 Exhaust System

When considering the exhaust gas system, the type of fuel and its particulars should belooked into closely. Operating on methanol would mean emission of CO2 and SOx belowlimits for the ECA areas. However when looking at the emitted NOx a SCR should be

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installed as part of the Exhaust Gas Cleaning System (EGCS) to comply with rules andregulations in when sailing in ECA areas.EGCS can either be placed in engine rooms or in the exhaust casings. Placement in theengine rooms comes with the challenge of deck spacing. Placement in the exhaust casinghas the challenge of exhaust casing size available, structural strength, and stability issuesdue to equipment weight. Although it can be noted that due to the particulars of thevessel the available space for exhaust system both in the engine room and in the exhaustcasing are appropriate.The SCR system is an emission after-treatment system compliant with various NOx

emission reduction needs, such as IMO Tier III. The Wärtsilä NOx Reducer can betailor-made or come as standard available in several different sizes and shapes (Wärtsilä,2015). The main components that are included in the standard scope of supply are reactorhousing, catalyst elements, soot blowing unit, urea injection and mixing unit, urea dosingunit, control and automation unit, urea pump unit, and air unit (Wärtsilä, 2015).The reactor housing dimensions give an indication of the minimum space reservation forthe exhaust casings. One SCR is installed per engine and exhaust gas pipe (Wärtsilä,2015). Figure 7.16 and Table 7.13 show the reserved space for the compact SCR witha built in silencer including maintenance clearance as well. The main and the auxiliaryengines fall within the power ranges that stated in Table 7.13.

Figure 7.16: Compact catalyst layers reactor with integrated silencer (Wärtsilä, 2015)

Table 7.14 gives an indication of the minimum exhaust casing size necessary when con-sidering these alternatives and given a 800 mm service space each side as well (Wärtsilä,2015). It is important to note that these values are only indicative because Wärtsilä alsotailor makes SCRs based on space limitations as well as operating fuel types (Wärtsilä,2015).

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Table 7.13: Typical dimensions of SCR with built in silencer (Wärtsilä, 2015)

Engine Size [MW]L [mm] (incl.

150mminsulation)

H [mm] (incl.800mm clearance

each sides)

W [mm] (incl.800mm clearance

each sides)

4.8-5.8 6400 3840 38801.1-1.35 5080 2760 2760

Table 7.14: Initial size estimate of exhaust casing

Genset Size [MW] NumberCross-sectionalarea of SCRreactor [m2]

Volume [m3]

4.8-5.8 2 14.8 92.41.1-1.35 2 7.29 36.5

Total 23.8 128.9

7.8 Waste Heat Recovery Unit (WHRU)

As seen in Table 7.4, during operations of the engines the heat loss takes up a considerablybig part in the energy transferring model. This amount of heat can be re-utilised to gainextra energy and use it for electricity generation to make the operation of the vesselmore efficient and environmentally friendly. This can be achieved by implementing heatrecovery concepts and secondary cycles.

7.8.1 Economiser

Due to the high temperature and the heat flow of the exhaust gas, it can be utilised toproduce steam and through a steam turbine to generate electrical power.

The main component that is directly connected to the exhaust ducts are the economisersfor steam generation as can be seen in the system configuration in Figure 7.17.

The WHRS unit and their produced power can be designed during the basic designstage. At this point based on the installed main engines, boilers can be chosen and aspace reservation can be made for the WHRS. For the generated electricity by the systemthrough installing economisers 6% of the engine output on 75% MCR can be considered(MAN, 2015b).

Based on the current market different economisers can be considered to be installedon-board. Alfa Laval has boilers with multiple inlets, where the exhaust ducts comingfrom the main engines as well as auxiliary engines can be coupled into one economiser.To get the maximum efficient steam production, the actual engines running in differentoperational profiles need to be taken into consideration. However, before the boilersseparate SCRs have to be installed into the exhaust line.

Another possibility on the current market is a compact system that includes already

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Figure 7.17: WHRS Configuration (MAN, 2015b)

the SCR within the economisers. Currently a company called, Gesab provides so calledCatamizers for this purpose, although with only having the availability with one inlet(Gesab, 2017). This solution can offer more cost efficiency, reduced weight as well as lessspace required.Utilising both technologies, and taking into account the seperate exhaust casings on portand starboard side, respectively, the final system configuration includes two separatecompact Catamizers for each of the auxiliary engines and a multiple inlet boilers forcoupling the main engines. The schematic drawing for this system can be seen in Figure7.18.

7.8.2 Power Turbine

In addition to the boilers in the exhaust system, in terms of recovering energy an otheroption can be also discussed where the kinetic and thermal energy after the turbo chargeris being extracted by a power turbine (also known as exhaust gas turbine). This powerturbine can be linked together with a steam turbine when the electric power requirementis large. A coupled system can be seen in Figure 7.17.Usually the power turbine is installed in a separate line where part of the exhaust gasflow is by-passed the turbocharger. This is coupled with a generator that converts thekinetic power to electricity on-board. A stand alone power turbine system, where thesteam from the economisers are used for heating can be seen in Figure 7.19.Nevertheless it should be noted that as a coupled system, when for instance the exhaustgas flow is by-passed the turbocharger, it would reduce the intake air, subsequently theexhaust gas temperature after the turbocharger will increase. This would further increasethe obtained generated steam, which can be used for electricity production.

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Figure 7.18: Multiple Economisers for maximum efficiency

Figure 7.19: Stand Alone Power Turbine System (MAN, 2015b)

Choosing the right system again, mainly depends on the power demand on-board, theoperational profile as well as the turn over time for the solution installed on-board.

For maximum efficiency and energy recovery purposes a coupled a multiple phased (high-low pressure) steam and power turbine system can be installed on-board, which is saidto give a 10% power boost of the output powers when operating the engines on 100%

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MCR. The overall schematics for the coupled system can be seen in Figure 7.20 and inAppendix B. Furthermore, this can also be coupled together with system based on anORC to extract the remaining available energy from the exhaust gases and from differentcooling liquids.

Figure 7.20: 2 phased Steam and Power turbine system for maximum efficiency

7.8.3 Heat Extraction from Cooling Liquids

To make the best energy regain after employing the economisers and the power turbinesin addition to the system as seen in Figure 7.19 it can be coupled with technologies thatutilising the Organic Rankine Cycle (ORC) theory to extract the remaining waste heatfrom exhaust gases after economisers and cooling liquids such as jacket water of mainand auxiliary engines.The ORC is a thermodynamic cycle that uses different working fluids where it vaporisesa pressurised fluid by heat source (exhaust gases or jacket water), when this fluid turnedinto steam, this steam will rotate a turbine and the electricity is generated (M.Grljušić,V.Medica and G.Radica, 2015). Figure 7.21 clarifies the ORC system.The working fluid can be chosen depending on the heat source temperatures where eachworking fluid has different thermodynamic and transport properties. Since there are twodifferent heat sources (exhaust gases and jacket water), two working fluids can be chosenfor high and low temperature cycles: R113 for high running temperature (exhaust gases,380 ◦C) and R245fa for low running temperature (jacket water, 96 ◦C).Table 7.15 shows the thermodynamic and transport properties of R113 and R245fa.

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Figure 7.21: Schematic layout of ORC

Table 7.15: Working fluid properties (Ethermo Calculation Platform, 2009)

Molecularweight

Normal boilingpoint

Criticaltemperature

Criticalpressure

Workingfluid [g/mol] [◦C] [◦C] [MPa]

R113 187.375 47.585 214.06 3.3922R245fa 134.048 15.4 154.01 3.651

Based on the research by Grljušić, M. et al., 2015, the power recovered from exhaust gasescan be calculated with Equations (7.1) to (7.4) (M.Grljušić,V. Medica and G.Radica,2015). First, the working fluid mass flow can be calculated depending on the exhaustheat transfer Equation (7.1).

mR113 = mex · (hout − hin)(h5 − h2) (7.1)

The turbine work can be calculated with Equation (7.2).

Wtb = mR113 · (h5 − h6) = mR113 · (h5 − h6s) · ηtb (7.2)

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The pump work can be calculated with Equation (7.3).

Wpump = mR113 · (h2 − h1) = mR113 · (h2 − h1s)ηpump

(7.3)

In Equation (7.3), the isentropic efficiency of turbine ηtb = isentropic efficiency of pumpηpump = 0.8. Hence, the net work is obtained with Equation(7.4).

Wnet = Wtb − Wpump (7.4)

In the same way, the power recovered from jacket water (low temperature) can be calcu-lated with Equations (7.5) to (7.8) (M.Grljušić,V. Medica and G.Radica, 2015).The working fluid mass flow can be calculated depending on the cooling water heattransfer, Equation (7.5).

mR245fa = mw · (hout − hin)(h5 − h2) (7.5)

The turbine work can be calculated with Equation (7.6).

Wtb = mR245fa · (h5 − h6) = mR245fa · (h5 − h6s) · ηtb (7.6)

The pump work can be calculated with Equation (7.7).

Wpump = mR245fa · (h2 − h1) = mR245fa · (h2 − h1s)ηpump

(7.7)

Hence, the net work is obtained with Equation (7.8).

Wnet = Wtb − Wpump (7.8)

Figure 7.22 shows the Temperature-Entropy diagram (T-S) for high temperature cycle(R113) and Table 7.16 shows the values for each point. Figure 7.23 shows the Temperture-Entropy diagram (T-S) for low temperature cycle (R245fa) and Table 7.17 shows thevalues of pressure, temperature, enthalpy and entrophy for each point can be definedeasily by calculation platform (Ethermo Calculation Platform, 2009).Finally, the result of the output power recovered by ORC is 3 MW when operating 100%load and 2.5 MW when running 75% load.

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Figure 7.22: T-S diagram of R113

Table 7.16: R113 working fluid (Ethermo Calculation Platform, 2009)

Temperature Pressure Entropy EnthalpyPointnumber TP [K] P [MPa] S [kJ/kg.K] h [kJ/kg]

1 311 0.0729 0.755 234.6962 313 0.0782 0.756 236.5613 413 1.0142 1.398 336.34 413 1.0142 1.656 442.75 448 1.8704 1.672 458.986 311 0.0729 1.616 407.997 311 0.0729 1.556 234.696

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Figure 7.23: T-S diagram of R245fa

Table 7.17: R245fa working fluid (Ethermo Calculation Platform, 2009)

Temperature Pressure Entropy EnthalpyPointnumber TP [K] P [MPa] S [kJ/kg.K] h [kJ/kg]

1 281 0.0754 1.03 210.252 283 0.082 1.04 212.833 323 0.3236 1.22 266.2994 323 0.3236 1.76 440.9265 343 0.6096 1.773 454.9966 298 0.1482 1.75 422.7777 281 0.0754 1.73 408.9

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7.9 Fuel System

Operating the engines on methanol fuel, requires different safety regulations and technicalchallenges as previously mentioned in Section 7.3.2.1.

Due to the current technical availability the engines to be delivered as diesel enginesoperating on MGO, but prepared for conversion to methanol operation. The engineswill then be retrofitted with a separate methanol injection system. The original dieselinjection system will be kept providing ignition by pilot fuel, during methanol operationand also providing fuel flexibility and maintain possibility to still operate on 100% MGO.

The main technical points that should be accounted for when designing a separatemethanol fuel line is to install the following equipment that differs from the generalfuel system:

• Low Flash-point Fuel Supply System

• Fuel Valve Train

• Purge return system

A schematic overview of the duel fuel system can be seen in Figure 7.24 and detailed inAppendix B.

Figure 7.24: Line drawing for Diesel-Methanol fuel system

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7.10 Ventilation System

To provide thermal comfort and acceptable indoor air quality, ventilation system is de-signed. The ventilation is very necessary to provide the engine room with air required forcombustion and evacuating the heat emission and according to the total airflow consistsof airflow for combustion and airflow for evacuation of heat emission (ISO, 1998). Airflowfor combustion can be calculated with Equation (7.9) (ISO, 1998).

qc = qdp + qdg + qb (7.9)

In Equation (7.9) qdp is the airflow for combustion for main engines, qdg is the airflow forcombustion for auxiliary engines,and qb is the airflow for combustion for boilers. Airflowfor evacuation of heat emission can be calculated with Equation (7.10) (ISO, 1998).

qh = φdq + φdg + φb + φp + φg + φepρ · c ·∆TP

− 0.4(qdp + qdg)− qb (7.10)

In Equation (7.10 φdq is the heat emission from main engines, φdg is the heat emissionfrom auxiliary engines, φb is the heat emission from boilers, φp is the heat emission fromsteam and condensate pipes, φg is the heat emission from electrical air-cooled generators,and φep is the heat emission from exhaust pipes.The total airflow of 23 m3/s is obtainedusing Equation (7.11) (ISO, 1998).

QA = qc + qh (7.11)

7.10.1 Ventilation Type

The design ventilation tunnel is has routing factor FRouting = 1, presented in Figure 7.25.

Figure 7.25: Designed ventilation tunnels

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In general, the intake airflow should start from the lowest point in the engine room andthe exhaust airflow should start from the highest point in the engine room on the oppositeside. This system type minimises efficiently the heat released into the engine room andair temperature in the exhaust air duct will be higher than engine room air temperature.

7.10.2 Duct Sizing

The cross section of ventilation duct can be calculated with Equation (7.12) (The Engi-neering ToolBox, 2017).

Ad = QA/VA (7.12)

In Equation (7.12), QA is airflow rate m3/s, VA is airflow velocity m/s, and Ad is thecross section of duct m2. The estimate cross sectional area of the ducts is 0.85 m2 Thelength of the exhaust duct, Lex, is 30 m and the length of the intake air duct Lin is 17.5m.

7.10.3 Choosing Intake and Exhaust Air Fans

Since the airflow rate is 23 m3/s, 10 intake air fans are chosen to provide the engine roomwith airflow needed for both combustion and evacuation of heat emission where, each oneprovides 2.5 m3/s. The performance data of ventilation fan is given by Table 7.18.

Table 7.18: Performance data of AC fan 600x600 mm (International Marine Airflow,2017)

Size Voltage[V]

Operating[kW] Flux [L/s] Noise

[dB]Pressure[Pa]

600x600x400(deep)

240 or 3Phase 1.5 2500 @1400 rpm 90 200

7.10.4 Accommodation and Cabins

In terms of accommodation and cabins, minimum fresh air supply quantity per personshould be 0.01 m3/s according to (DNV-GL, 2017k).

7.11 Water Systems

7.11.1 Fresh Water Generator

Fresh water generation is a very important aspect of ship operations since here the wa-ter required not only for drinking by the crew is determined but also for operations likelaundry and kitchen. Fresh water is also used as a coolant to the heat from other ma-chinery. The process of producing fresh water is very basic. Seawater is evaporated bysupplying heat from the jacket water outlet of the main engines and then the vapours are

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cooled using seawater to obtain freshwater. The fresh water generator plant used here isWärtsilä Serk Como Single Stage Desalination system which uses the process of vacuumdistillation to remove the salt water in the system. In vacuum distillation, the pressureabove the liquid mixture is reduced to less than its vapour pressure which then leads tothe boiling of the most volatile liquid which in this case would be water. In Figure 7.26the principle behind the generation of fresh water system can be seen.

Figure 7.26: Working principle of the fresh water generator System (Wärtsilä, 2017b)

The freshwater consumption per person on-board is assumed to be 200 litres per day.That gives an estimated consumption of 5000 litres per day by a crew of 25.In addition to the freshwater generation for drinking, an additional fresh water generatorfor technical water is needed. For this, Wärtsilä Serck Como Multi Stage Flash Evapo-rator was selected. It has a capacity of 1500 t/day and the produced distillate has verylow salt content making it suitable for use as technical water.

7.11.2 Sewage Water

For the waste water treatment, plants from ACO Marine were chosen primarily becausethey offer biological processing of the waste water thus eliminating the need to use chlori-nation and/or UV filtration. They follow the IMO revised guidelines for effluent standardsand performance test procedures for sewage treatment plants mentioned in RESOLU-TION MEPC.227(64). It is to be noted that vessels with 400 GRT and above which arecertified to carry more than 15 persons are required to comply with the revised guidelines

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1 January 2016 on-wards (ACO Marine, 2017e).ACO Marine offers two treatment plants:

1. ACO Maripur NF Membrane Bio Reactor (Figure 7.27), and2. ACO Clarimar MF Biological Sewage Treatment System (Figure 7.28).

Figure 7.27: ACO Maripur NF Membrane Bio Reactor (ACO Marine, 2017d)

Of the two options provided for sewage treatment by ACOMarine, ACO Clarimar MF Bi-ological (Bio-Sword) Sewage treatment plant was chosen since its unique properties allowoperation with bio-mass concentration in activation chamber up to four times higher thanthose of conventional settling type sewage treatment. By operating such high concentra-tions, a greatly reduced activation tank volume is achieved with a significant reductionin both the footprint and maintenance envelope requirement. Since it uses UV filtrationtechnology, it eliminates the need for settling tank and chlorination. The use of in linemounted UV lamp also eliminates the need for use of any chemicals in the process (ACOMarine, 2017b).In addition to the above features, the self cleaning ‘Bio-Sword’ with UV filtration tech-nology exceeds dramatically all IMO requirements. It is manufactured entirely in the EUfrom high performance materials which, unlike coated black steel, are completely corro-sion resistant and light weight modular design concept for simple installation requiringonly one power connection.It has lowest running costs of any sewage treatment plant onthe market with minimal operator intervention and is unaffected by ship movement orvibration. The material of construction is ‘ACO composite PPFR GREY’ which has ahigher corrosion resistance and is cheaper than Stainless Steel 316L used for making ACOMaripur NF (ACO Marine, 2017b).Figure 7.29 gives an overview of the sewage treatment system on-board the vessel. The

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Figure 7.28: ACO Clarimar MF Biological Sewage Treatment System (ACO Marine,2017c)

lines in red represent the flow of the black water while the lines in blue represent the flowof grey water.

Figure 7.29: Overview of Sewage Treatment System

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ACO also provides for a water treatment unit for recycling waste water from wastewater treatment plants so that it can be used as potable water. This can be used tocompliment the fresh water generator and thus really optimise the water consumptionon-board the vessel (ACOMarine, 2017a). For the vessel, ACOWM3-50 has been selectedas a complimentary system to the main fresh water system.

7.11.3 Cooling Water System

Two types of cooling systems are typically used on-board ships (Wankhede, 2017).1. Sea Water Cooling System- Sea Water is directly used as a median to cool the

machinery in the engine room.2. Central cooling system- Fresh water is used in close circuit to cool down the engine

room machinery. The fresh water that comes back from cooling the machinery isfurther cooled down using sea water in a sea water cooler.

The central cooling system comprises of three circuits.1. Sea Water Circuit: Sea Water is used as a cooling median in large heat ex-changers

which cool the fresh water returning from cooling the machinery in a closed circuit.2. Low Temperature Circuit: This circuit is used to cool down the low temperature

machinery like some of the auxiliary systems and is directly connected to the seawater cooler. The total amount of low temperature freshwater is maintained in thesystem in balance with the high temperature water with an expansion tank whichis common to both systems.

3. High Temperature Circuit: This mainly comprises of jacket water system of themain engine where the temperature is quite high. The system normally comprisesof jacket water system of the main engine, the fresh water generator and the Dieselgenerator during standby.

Figure 7.30 describes the central cooling system on-board the vessel.

Figure 7.30: Line diagram of Central Cooling system

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7.11.4 Ballast Water

As the number of vessels in the oceans increases with time, dramatic examples of thedevastation caused by the invasive species on the marine wildlife are more visible. Theinvasive species are the wildlife that get collected with the ballast water in one re-gion,transferred to another region and then harm the ecosystem in that region. Themost effective way to limit the spread of ballast water invasive species is to prevent theirintroduction. In 2004, IMO introduced the Ballast Water Convention (BWC) which willenter into force from 8th September 2017 to address the Control and Management ofShips’ Ballast Water and Sediments for all sea going ships greater than 400 gross tonnageusing ballast water (Wärtsilä, 2017a). Ships will be required to manage their ballasttanks to remove or render harmless the ballast water discharge of invasive species.

The ballast water on-board the vessel is treated by Wartsila Aquarius EC BWMS. Ituses a two stage process, filtration and electro-chlorination for the treatment and isoperational in all environmental conditions. The filtration process takes care of theparticulates, sediments, zooplankton and phytoplankton over 40 microns. The filters arecleaned automatically thus making the process very efficient. The Electro-Chlorinationcell module generates sodium hypochlorite from sea water which is then pumped to mainballast line for efficient disinfection of the filtered ballast water. The ballast water isdischarged overboard after monitoring its Total Residual Oxidant (TRO). Neutralisationeffectiveness is continuously monitored to ensured compliance with MARPOL dischargelimit (Wärtsilä, 2017e).

Figure 7.31 presents an overview of the ballast water treatment system that will be usedon-board the vessel.

Figure 7.31: Line diagram of Ballast Water Treatment

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7.12 Anchoring and Mooring Equipment

To obtain the equipment necessary for mooring and anchoring, according to the classifi-cation society, the equipment number (EN) must be calculated. It is possible to calculatethe equipment number with Equation (7.13) provided from the rules (DNV-GL, 2017d).

EN = ∆2/3 + 2BH + 0.1A (7.13)

where, ∆ is moulded displacement in ton, B is moulded breadth of ship, H is effectiveheight in m from the summer load waterline to the top of the uppermost deck-house, Ais area in m2 in profile view of the hull, superstructures and houses above the summerload waterline, which is within L of the ship.Since EN is 3980, the ship needs 2 anchors of 11 700 kg and cables and towlines can bespecified in Table 7.19 (DNV-GL, 2017d).

Table 7.19: Minimum dimensions of required mooring equipment (DNV-GL, 2017d)

Stud-link chain cables Towline Mooring lines

Quantity 1 1 6Length [m] 687.5 300 200

Diameter [mm] 107 - -Breaking strength [kN] - 1471 647

In terms of windlass and chain stoppers: the normal lifting force is 430 kN, mean hoistingspeed is 9 m/min, and the required lifting power is 64 kW.

7.13 Optimisation of Power Plant

The rates of use of the different system components and the 2nd iterative power demandcould be estimated for each of the operational profiles such as port, manoeuvring, openwater and loading/unloading as mentioned in Section 7.4. During the estimation of thepower demands the following assumptions were made:

• Safety equipment is not running in these profiles, only during emergency,• Machinery system rate was estimated with power consumption ratio (power need

during situation/installed power),• Ballast and Bilge systems were estimated to be in 100% use all the time. In ad-

dition, ballast water systems have no significant impact to total power need, sinceduring unloading the vessel need, to be counterbalanced due to off symmetry of theunloading platform

• Communication is in full use in every situation, and• Battery Packs to cover full hotel loads when in port as well as load variation during

DP unloading.

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When considering the most efficient running point of the engines installed on-board, theload diagram would define the power and speed limits for the optimum efficient runningpoint. Further, since the most efficient operational, design speed and the contractualspeed might as well differ, in order to have safety clearance in the design the optimalMCR was set to around 75%.Taking into consideration the preliminary engine configuration, the available power forthe optimum running points can be seen in Table 7.20.

Table 7.20: Available power at different operational points

MCR ME 1[kW]

ME 2[kW]

AE 1[kW]

AE 2[kW]

Battery[kWh]

WHRU[kW]

Emer-gency[kW]

100% 5665 5665 1140 1140 1000 817 76090% 5099 5099 1026 1026 73575% 4249 4249 855 855 613

These optimum operating loads and the estimated power consumption of the differentsystems were used to optimise the engine configuration for each operating profile. De-tailed electric balance of the different operational profiles can be seen in Appendix A. Asummary can be found in Table 7.21.As was predicted earlier, the 2 auxiliary engines, with the battery pack as well as theextra power boost from the Waste Heat Recovery Unit allowed for good flexibility forthe different operational profiles. The overall arrangement allows for the engines tobe running at their optimal operating range for all profiles. The actual engines beingoperated under different operational conditions can be also seen in Table 7.21.It should be noted that the 1 MWh battery storage unit plays as a backup power foremergency situations as well as for peak shavings of the engines, hence it was not takeninto account for the overall power calculation, as in continuous power generation purposes.

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Table 7.21: Provided power and configuration in different operations

OpenWater [kW]

DPAnchor[kW]

Unloading[kW]

PortManoeuvre

[kW]

Harbour[kW]

Required Power 7747 4948 6525 4494 64515% Margin 8908 5690 7503 5168 741Avail. EngPower 10208 5104 8498 5104 855

WHRU 612 306 612 306 0Total PowerProvided 10820 6410 9110 5410 855

Configuration 2M12A2B3W4 1M W B 2M W B 1M 1A W B 1A or BDifference 18% 11% 18% 4% 13%

1 Main Engine2 Auxiliary Engine3 Battery Unit4 Waste Heat Recovery Unit

7.14 Energy Efficiency Design Index

Energy Efficiency Design Index (EEDI) was adopted by IMO in 2013 with the intentionof making ship designers consider energy efficiency measures which will be valid acrossthe globe for the industry and applicable to all countries. These measures can be theuse of more energy efficient or less polluting equipment and engines. While EEDI doesnot direct the industry on what energy efficient technology to use on-board the ship,it is a performance based mechanism which makes sure that the technology is used. Itprovides a specific figure for an individual ship design expressed in grams of Carbondioxide per ship’s capacity mile. Smaller the EEDI, more efficient is the ship’s design.The CO2 reduction level will be tightened every 5 years in order to keep pace withthe technological developments of new efficiency and reduction measures (IMO, 2017).Equations 7.14 through 7.18 describe the steps used in calculating the EEDI.

COME2 emissions =

M∏j=1

fj

(nME∑i=1

PME(i) · CFME(i) · SFCME(i)

)(7.14)

EEpowergeneration = M∏

j=1fj

· nPTI∑i=1

PPTI(i) −neff∑i=1

feff(i) · PAEeff(i)

CFAE · SFCAE(7.15)

COAE2 emissions = (PAE · CFAE · SFCAE) (7.16)

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7 Machinery

InnovativeEE for Propulsion =neff∑i=1

feff(i) · Peff(i)CFME · SFCME (7.17)

Transport work = fi · fc · Capacity · fw Vref (7.18)

The EEDI is calculated starting with the summation of CO2 emissions from the propulsionsystem (Equation (7.14) and Equation (7.15)) and auxiliary engines (Equation (7.16)),subtracted by the CO2 emission reduction measures (Equation (7.17)). The amount isfinally divided bby the transport work (Equation (7.18)), resulting into the amount ofCO2 emitted in grams per ton nautical mile.The EEDI for the vessel was calculated to be 20.93 g/t·NM, but it is important to benoted that this calculation does not take into account that the vessel will be run onMethanol and hence does not give an accurate estimate of the CO2 emissions from thevessel. Figure 7.32 represents a baseline for bulk carriers which the vessel was consideredas base during the calculation.

Figure 7.32: EEDI reference curve for bulk carriers (IMO, 2016)

EEDI emphasises the need to enforce power limits for new ships thus reducing theiroperational speeds and as a result the carbon emissions. It is worth mentioning thatparameters for diesel electric or hybrid system propelled vessels are difficult to be includedin the formula. This may change in future as energy efficiency is expected to become anintegral part of every ship designing project. Designing a new vessel to fit the targetsof EEDI however will not be justified unless energy efficiency is monitored an balancedthroughout the operational life of the vessel.The reference speed is highly coupled with the necessary installed power on-board, how-ever the power can be lowered by lower the resistance of the vessel, thus a very efficienthull design from a hydrodynamic point of view is essential. The stated conversion factor(Cf ) between fuel consumption and CO2 emission depends on the fuel being used. At

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this current stage methanol to be more accurate bio-methanol can offer the lowest valueto be used as Cf factor (IMO, 2014). The specific fuel oil consumption (SFOC) mainlydepends on the engine manufacturer. The Wärtsilä 31D engine offers economical andefficient fuel consumption during operation, hence these values can be considered low incontrast to different manufacturers and different engine types. The shaft generator partcan be waived, due to the vessel is designed as a methanol-electric power plant.Nevertheless, batteries can offer a reduction factor due to as a measure as an innovativeelectrical energy efficient technology. Further decrease in the numerator can be achievedapplying the reduction factor based on the waste heat recovery unit. Installing theseinnovative technologies on-board and considering in the calculation could result with alower EEDI value.

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7 Machinery

128

8 Alternative RORO OperationsDespite the M/S Big Buoy being a specialised cargo vessel, it is important to considerpotential future uses of the ship. Through the development of the general arrangementof the ship, it became evident that the M/S Big Buoy shares many characteristics witha traditional RORO ship with its large, continuous cargo holds. In addition to this, theship is designed to withstand the severe weather in the North Sea, and thus, should beable to travel with minimal restrictions on its area of operation. A short investigationhas therefore been conducted to investigate the possibility of using the M/S Big Buoy asa RORO ship without significant changing its structures or machinery.As a RORO ship, the loading of the M/S Big Buoy would change significantly. Thecurrent buoys have a very low weight-to-volume ratio, and therefore, in any RORO op-erations the weight density of the cargo would be much higher. With a loading of 1.5t/m2, the M/S Big Buoy reaches a draft of 7.5 m, which is a reasonable draft for theRORO operations. This increases the payload from 2400 t as a buoy carrier to 16 914 tas a RORO ship.

8.1 General Arrangement Considerations

To use the M/S Big Buoy as a RORO vessel, a few changes to the cargo handlingequipment are necessary. First, the work platforms on the ramp need to be removedas they would serve no purpose for traditional RORO operations. The ramp and theelevator would also need to be made completely watertight up to the weather deck tomeet the damage stability requirements as detailed in Section 8.5. The ramp may needto be modified to fit loading facilities in port, including the installation of a side ramp,if necessary. The current cargo elevator can still be used as mean for internal cargomovement between decks.

8.2 Structural Considerations

The original structures of theM/S Big Buoy are designed to be able to support a dynamicload of 1.5 t/m2 which is sufficient for many RORO applications. The increased draft of7.5 m is also incorporated into the current midship section design. The structures couldbe improved by adding pillars to decrease the span of the beams. In this way, it is likelythat the decks could support even high loads.

8.3 Propulsion Estimations

With the increase in the payload, the new draft changes the many factors for the hydro-dynamics and the propulsion system. It alters the hydrodynamic behaviour and conse-quently, the propulsion requirements. The main hydrodynamics particulars of the newload environment is presented in Table 8.1.

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8 Alternative RORO Operations

Table 8.1: Main hydrodynamics particulars for 7.5 m RORO Operation

Parameter Value [unit]

Draught, T 7.5 mDisplacement, ∆ 33 121 tBlock Coefficient, CB 0.681 -Prismatic Coefficient, CP 0.691 -Waterplane Coefficient, CW 0.842 -Design Speed, VD 16.0 knotsFroude number, Fn 0.199 -Wetted Area 7 244.2 m2

Waterplane Area 5 326.3 m2

Effective Power, PE 4.322 MWHull efficiency, ηH 98.00 %Propeller diameter, DP 3.50 mPropeller efficiency1, η0 58 %Delivered power, PD 9.198 MW

1 Same propeller as for the wave transport andinstallation design

The design for the wave buoys transport and installation was optimised to match theclient’s yearly need (as explained in Chapter 3), resulting in the moderate design speedof 15 kn. The calculation of the required power for the dimensioning of the engines takesinto account sea margin and also reduces the engine loads to a 75% MCR, ensuring thatit is seaworthy and economic.

To evaluate the available power for a possible conversion for a RORO vessel, the revertdesign process was conducted. From the available installed power, 2162 kW are reservedfor vessel loads and the remaining 10 822 kW can be focused to propulsion. Accountingfor a 90% MCR, transmission losses, hull and propeller efficiency, approximately 4322 kWcan be used to effective power. Therefore, it is possible, through resistance estimations,to determine the operational speed in a 7.5 m draft and RORO operation.

Using similar methodologies as in Chapter 5, the operational speed is estimated to beapproximately 16.0 kn. This is rather conservative and further CFD resistance estimationshould be carried out, especially to evaluate the resistance of the wetted transom.

The new load on the same propeller reduces its efficiency to approximately 58%, butthe increase in the draft assures that cavitation does not occur. This efficiency can beregarded as rather low, meaning that a propeller re-design and retrofit would be the mostbeneficial for the conversion of the vessel.

If the RORO concept is of real interest for the customer, it might be interesting to have inmind different hull concepts, aiming to increase propeller size, performance and payload.The closed bow concept might not be the most efficient for a RORO vessel. The actualrounded transom was designed to minimise the displacement while still satisfying cargo

130


space requirement. For a RORO vessel, a more "squared" design increases the availabledeck space and payload, simplifying manufacturing and without, in this case, significantlyimpacting the displacement.

8.4 Intact Stability

The evaluation of the intact stability was carried out similarly to the one made in Section5.3.2, but only considering the fully loaded case since ballast conditions are going to besimilar.The new fully loaded case of a 7.5 m draft RORO concept is presented in Table 8.2, withballast enough only to stabilise trim and heel. The GZ curve is presented in Figure 8.1.

Table 8.2: Preliminary RORO displacement estimate

Item Total Weight LCG TCG VCG[t] [m] [m] [m]

Lightship 13 245.3 104.1 0.1 12.5DeadweightLower Cargo Hold 3588.3 66.5 -0.5 7.5Main Cargo Hold 6151.9 81.0 0.0 17.5Upper Cargo Hold 7173.4 80.5 0 27.5Fuel 3139.4 67.7 0.0 7.2Ballast & Consumables 736.7 121.3 4.9 10.7

Total Displacement 33 819.3 81.7 0.1 15.3

The GZ curve assembles much more to a common vessel, having a smaller maximumvalue, area and GM compared to the 5 m draft design. This will also significantly impactthe motions in a positive manner. The vessel still comply with all criteria stipulated bythe class rules, but with a smaller margin.

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Figure 8.1: GZ-curve for the RORO fully loaded departure loadcase

8.5 Damage Stability

The evaluation of the damage stability was carried out similarly to the one made inSection 5.3.3. With the increase in draft, the clearance to the margin line (presented inFigure 5.6) is considerably lower. This compromises the attained index (approximately0.1), requiring new zones to be created.In order to pass the damage stability requirements, the structure up to the weather deckcould be made watertight, as well as the stern ramp, effectively moving the margin lineupwards. This will considerably increase the attained index.

132

9 Future WorkThis chapter gathers ideas, thoughts, considerations that aroused during the developmentpart of the project that were not possible to execute in time.

9.1 General Arrangement

The most challenging aspect of the general arrangement design is the efficient use ofspace. The large volume requirement of the buoys resulted in a very large ship with morespace than necessary in the forward end of the ship dedicated to the accommodationblock and engine room. This space was further increased with the introduction of theULSTEIN X-BOW® . It would be beneficial to re-evaluate the overall length of theM/S Big Buoy in the future to remove unnecessary length, which is arguably the mostexpensive dimension. The engine room and accommodation arrangements could then bereused to utilise the space in a more efficient manner.Time limitations presented a large challenge in the design of the M/S Big Buoy. Oneparticular aspect of the design that could be improved with time is the details of thecargo handling operations and equipment. Currently, the main cargo handling equipmentis defined, however, details such as weather protection for workers on the ramp or precisestorage methods for empty frames could be better defined.Finally, the ship was designed for buoys that are 38.5 m in length and a maximumdiameter of 8 m. The length of the upper cargo holds was chosen to specifically fit fourbuoys lengthwise. The elevator was also dimensioned to fit one buoy at a time per deck.Since the buoys are also undergoing constant design updates, future iterations of thegeneral arrangement should work to improve the flexibility of the ship to accommodatechanges in length of the buoys.

9.2 Hydrodynamics

Stability-wise, the vessel hull-structure configuration complies with all intact and damagestability rules. The main issue is the excess of transverse righting arm, GMT, which isslightly high, impacting the motions of the vessel. A lower transverse metacentric heightis desirable, resulting in lower accelerations. The damage stability was one of the initialconcerns, as very large cargo holds constitutes the largest part of the vessel. Thus, adesign 4 m double side wall was designed to contain the flooding by any type of lateraldamage. With the damage stability investigation, it became clear that the M/S Big Buoypasses the criteria and with considerable margin. Therefore, in the future, an investigationof the minimum lateral side wall required to pass the damage stability should be carriedout. This would be a possibility to increase cargo space and reduce structural weight.The M/S Big Buoy was optimised to perform best in sea-wave conditions. Although thiswas the main focus of the hydrodynamic group, it does not mean that further improve-ments can be made. There are always known and upcoming solutions that can be used

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9 Future Work

in the future to increase the vessel responses.The study of different hull concepts provided valuable data for the decision making, butthese could be biased due to their differences in displacement, waterline shape and evenLPP . Therefore, it is recommended to further evaluate their differences in detail beforea final choice.The evaluation of the added wave resistance should be focused on the operational area ofthe vessel. Thus, as future work, with an analysis of the specific route is possible to extractwind and wave directions for the entire operation. From that, the hull can be optimised tooperate in those sea conditions. To compare different hull designs, a monetary evaluationof how it impacts the travel time and, consequently, fuel consumption might be the bestevaluation tool.As mentioned in Section 5.7.2, the propeller design was based on default values of Open-Prop. The final propeller design should be further evaluated with more recent methodolo-gies and for a wide range of parameters. Thus, it is believed that the propeller efficiencycan overcome the 70% barrier.For the RORO conversion, a full re-design and retrofit of the propeller is necessary toincrease the efficiency to normal levels.Manoeuvring of vessels with pods gives a number of advantages as long as the correctstrategy is applied (Verkerk, 2002). The current skeg design was fitted to improve coursestability, but model scale tests and simulations should be used to better estimate theperformance. These tests and simulations can determine how course stable the hull underevaluation is, as well as zig-zag and crash stop manoeuvres performances to satisfy IMOcriteria. Model tests might be unavailable within the scope of this project, but numericalsimulations can be run to approximate the vessels course keeping capabilities.The actual combination of bow thrusters and Azipods assure that the turning circlediameter is approximately the length of the vessel, but it is something to be evaluated inthe future.The DP system is a strict requirement for the installation of buoys, but it was analysedonly with full operational power available. Thus, a more in-depth evaluation for cases ofdamage or unavailability of engines should be carried out. This also includes the correctdesign of watertight decks and bulkheads, ensuring redundancy and operational conditionin diverse situations.The environmental forces utilised to produce the DP capability plot (Figure 5.15) mightnot strictly represent the reality. Thus, it is recommended to re-evaluate the forcesand further study the DP operation system in detail to match the required operationalrequirement. This also requires close communication with the machinery design, keepingeverything within reasonable safety margins.

9.3 Structure

The FE analysis in this report investigated the structures in the midship part of thevessel, which is appropriate at this initial stage. However, a FE model simulating thewhole ship structure would provide more realistic results and is necessary in future designphases. A more complete FE analysis can also include the analysis of the vessel’s response

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9 Future Work

to several different load cases and sea conditions. Moreover, the choice of the type andlocation of boundary conditions and their effects should be further investigated.Additionally, a more detailed optimisation of the structural members should be done.This optimisation should be done to minimise the weight of the ship while maintainingthe simplicity of the manufacturing processes. Examples of this optimisation can includedifferent spacing between longitudinal and transverse members, adjusting the doublebottom height and side wall width, and refining the scantling selecting throughout thehull.An interesting future structural analysis could include an evaluation of the fatigue life ofcritical structures, critical crack sizes and fracture behaviour of the hull.Finally, more detailed structural drawings should be completed to create a more completeview of the ship’s structures. These could include, for example, a hull expansion plan,drawings of the forward and stern structures, and midship section drawing includingdetails such as brackets.

9.4 Machinery

The upcoming future emission regulation will determine more strictly the operation ofthe vessel as well as the different technical means being installed on-board to reduceemission of NOx, SOx as well as CO2. With these regulations and the possible extendingECA areas are forcing the owners to operate more and more efficiently and greener.With the increasing means of technology this could be achieved more easily to operate ondifferent type of fuels that are environmental friendly, such as Methanol or even possiblyto consider renewable energy such as wind or solar power as a primary source for power.At this point the overall operations of the engines and the system considerations formethanol are rather in initial stages. With the increasing demand towards greener fuelsthis possible will change and there will be engines available on the market designed tooperate particularly on methanol fuel as well as remain the retrofit kits for current dieselengines. For the fuel system safer and more feasible options can be available for storingand transfer from tank to engines on-board, which can be also standardised in time.Further, classification societies shall have better understanding of the overall applicationprocess of such a system for standardisation and setting up rules.The current system on-board is a hybrid methanol-electric system. Batteries and theircapacity as well as their prices will definitely change with the years to offer more efficientoptions for a hybrid system, nevertheless the size of the battery pack as well as themanagement system can be synchronised with the actual operational profile if that will bechanged in the future. Alternative options can also be considered to install on-board, forstoring energy such as fuel cells and any other future technologies that will be developed.One of the most important thing also, is the utilisation of the waste heat coming from theexhaust as well as the different cooling waters to recover as much energy as possible. Thiscan be achieved for instance extracting the kinetic and thermal energies. The vessel iscurrently equipped with the most efficient system considering economisers with a steamturbine and power turbine, as well as to further boost the achievable recovered energy,an organic Rankin cycle is considered for the different cooling liquids and remaining heatenergy of the exhaust. Other different means should be also evaluated and looked at

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in the future for energy recovery purposes. To this end a more detailed heat balancecalculation should be also set up.A more detailed SFI system should be created, subsequently a second and further phasesof the electric balance calculation shall be applied to gain a better and precise under-standing of the electric demand in each of the different operational condition. This givesthe base of designing the most efficient and economical power plant concept installedon-board, to better fit the power demand. In case of changing the operational profile ofthe vessel, the whole power consumption would need to be reevaluated, hence the enginelayout set up possible changed. The main purpose of considering multiple engines on-board supplied with a hybrid system is to create flexibility and economical operation indifferent design conditions. This is to ensure the engine is operating at its most efficientpoint as often as possible to save fuel and energy.With all these technical considerations taken into account, the economic, financial sideof the design can not be disregarded. The aim is to future achieve a design that correctlybalance all factors.

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ReferencesAarnio, M. (2015). The First LNG Cruise Ship Will Start a New Trend. Online.

LNG World Shipping. Retrieved from http://www.passengership.info/news/view,the-first-lng-cruise-ship-will-start-a-new-trend_39019.htm

ABB. (2009). Products for Marine Application (Tech. Rep.). Author. Re-trieved from http://www04.abb.com/global/seitp/seitp202.nsf/0/cb797b285bd3a5c3c12577ad004a9bfb/\protect\T1\textdollarfile/Products+for+marine+applications+low_res_111109.pdf

ABB. (2015). Azipod CO Product Introduction (Tech. Rep.). Author. Retrieved fromhttps://library.e.abb.com/public/85d7a5e53e6a8e6ec12577e7002d2359/Azipod_CO_Product%20Introduction_rev%20C_LowRes.pdf

ABB. (2017). Energy Efficiency Guide (Tech. Rep.). Author. Retrieved fromhttps://library.e.abb.com/public/ce940f43aa732297c1257b860031260f/ABB%20Marine%20Energy%20Efficiency%20Guide%2004062013.pdf

ABB. (2017). OCTOPUS-Office. (Version 6.4.5) [Computer Software].ACOMarine. (2017a). ACO Water Maker WM3. Retrieved from http://www.acomarine

.com/products/aco-water-maker-wm3/ACO Marine. (2017b). Biological Sewage Treatment System. Retrieved

from http://www.acomarine.com/products/wastewater-treatment-plants/mf-bio-sword-filtration-technology/

ACO Marine. (2017c). Biological Water Treatment System.ACO Marine. (2017d). Membrane Water Treatment System. Retrieved from

http://www.acomarine.com/products/wastewater-treatment-plants/membrane-wastewater-treatment-system/

ACO Marine. (2017e). Wastewater Treatment Plants. Retrieved from http://www.acomarine.com/products/wastewater-treatment-plants/

Babicz, J. (2015). Wartsila Encyclopedia of Ship Technology. Wärtsilä. Retrieved fromhttps://www.wartsila.com/encyclopedia

B. Allenström, D. L., & Ran, H. (2012, Oct). System Impact when using Wind, Waveand Solar Energy (Tech. Rep.).

BENTLEY SYSTEMS. (2015). MAXSURF Enterprise Suite. (Connection Edition V21Update 00.03) [Computer Software]. (Academic Version)

British Steel. (2017). Bulb Flats: Light weight corrosion resistant solution for plate stiff-ening. Retrieved from http://britishsteel.co.uk/media/40438/bulb-flats-brochure.pdf

Ceetron AS. (2015). Sesam Xtract. (Version 5.0-04) [Computer Software].Chakrabarty, A. (2017, Sep). How Bow Thruster is Used for Maneuvering a

Ship? Retrieved from http://www.marineinsight.com/marine-navigation/how-bow-thruster-is-used-for-maneuvering-a-ship/

Corvus Energy. (2015). The Leader in Energy Storage for Maritime Industry. Retrievedfrom http://corvusenergy.com/energy-storage-system-html/

Corvus Energy. (2016). Containerised Energy Storage System (Tech. Rep.). CorvusEnergy. Retrieved from http://corvusenergy.com/wp-content/uploads/2016/04/Corvus-Energy_Containerized-Solution_Nov2015.pdf

137

http://www.passengership.info/news/view,the-first-lng-cruise-ship-will-start-a-new-trend_39019.htm

http://www.passengership.info/news/view,the-first-lng-cruise-ship-will-start-a-new-trend_39019.htm

http://www04.abb.com/global/seitp/seitp202.nsf/0/cb797b285bd3a5c3c12577ad004a9bfb/\protect \T1\textdollar file/Products+for+marine+applications+low_res_111109.pdf



https://library.e.abb.com/public/85d7a5e53e6a8e6ec12577e7002d2359/Azipod_CO_Product%20Introduction_rev%20C_LowRes.pdf

https://library.e.abb.com/public/85d7a5e53e6a8e6ec12577e7002d2359/Azipod_CO_Product%20Introduction_rev%20C_LowRes.pdf

https://library.e.abb.com/public/ce940f43aa732297c1257b860031260f/ABB%20Marine%20Energy%20Efficiency%20Guide%2004062013.pdf

https://library.e.abb.com/public/ce940f43aa732297c1257b860031260f/ABB%20Marine%20Energy%20Efficiency%20Guide%2004062013.pdf

http://www.acomarine.com/products/aco-water-maker-wm3/

http://www.acomarine.com/products/aco-water-maker-wm3/

http://www.acomarine.com/products/wastewater-treatment-plants/mf-bio-sword-filtration-technology/

http://www.acomarine.com/products/wastewater-treatment-plants/mf-bio-sword-filtration-technology/



http://www.acomarine.com/products/wastewater-treatment-plants/

http://www.acomarine.com/products/wastewater-treatment-plants/

https://www.wartsila.com/encyclopedia

http://britishsteel.co.uk/media/40438/bulb-flats-brochure.pdf

http://britishsteel.co.uk/media/40438/bulb-flats-brochure.pdf

http://www.marineinsight.com/marine-navigation/how-bow-thruster-is-used-for-maneuvering-a-ship/

http://www.marineinsight.com/marine-navigation/how-bow-thruster-is-used-for-maneuvering-a-ship/

http://corvusenergy.com/energy-storage-system-html/

http://corvusenergy.com/wp-content/uploads/2016/04/Corvus-Energy_Containerized-Solution_Nov2015.pdf

http://corvusenergy.com/wp-content/uploads/2016/04/Corvus-Energy_Containerized-Solution_Nov2015.pdf

References

DNV-GL AS. (2016). Genie. (Version 7.4-16) [Computer Software].DNV-GL AS. (2017). Nauticus Hull. (Version 18.5.90.3278) [Computer Software].DNV-GL. (2016a). Methanol as Marine Fuel: Environmental Benefits, Technol-

ogy Readiness, and Economic Feasibility (Tech. Rep.). Online. Retrievedfrom http://www.imo.org/fr/OurWork/Environment/PollutionPrevention/AirPollution/Documents/Report%20Methanol%2021.01.2016.pdf

DNV-GL. (2016b, Jul). Rules for Classification of Ships: Part 2, Chapter 2 - MetallicMaterials. Retrieved from https://rules.dnvgl.com/docs/pdf/DNVGL/RU-SHIP/2017-07/DNVGL-RU-SHIP-Pt2Ch2.pdf

DNV-GL. (2016c, Jul). Rules for Classification of Ships: Part 3, Chapter 7 - FiniteElement Analysis. Retrieved from https://rules.dnvgl.com/docs/pdf/DNVGL/RU-SHIP/2016-07/DNVGL-RU-SHIP-Pt3Ch7.pdf

DNV-GL. (2017a). (Future) Fuels & Fuel Converters.DNV-GL. (2017b, Jan). Rules for Classification of Ships. Retrieved from https://

rules.dnvgl.com/ServiceDocuments/dnvgl/#!/industry/1/Maritime/1/DNV%20GL%20rules%20for%20classification:%20Ships%20(RU-SHIP)

DNV-GL. (2017c, Jan). Rules for Classification of Ships: Part 3, Chapter 10 - Spe-cial Requirements. Retrieved from https://rules.dnvgl.com/docs/pdf/DNVGL/RU-SHIP/2017-07/DNVGL-RU-SHIP-Pt3Ch10.pdf

DNV-GL. (2017d, Jan). Rules for Classification of Ships: Part 3, Chapter 11 - HullEquipment, Supporting Structure and Appendages. Retrieved from https://rules.dnvgl.com/docs/pdf/dnvgl/ru-ship/2017-01/DNVGL-RU-SHIP-Pt3Ch11.pdf

DNV-GL. (2017e, Jan). Rules for Classification of Ships: Part 3, Chapter 1 -General Principles. Retrieved from https://rules.dnvgl.com/docs/pdf/DNVGL/RU-SHIP/2017-07/DNVGL-RU-SHIP-Pt3Ch1.pdf

DNV-GL. (2017f, Jan). Rules for Classification of Ships: Part 3, Chapter 2 - GeneralArrangement Design. Retrieved from http://rules.dnvgl.com/docs/pdf/dnvgl/ru-ship/2017-01/DNVGL-RU-SHIP-Pt3Ch2.pdf

DNV-GL. (2017g, Jan). Rules for Classification of Ships: Part 3, Chapter 3 - StrucutralDesign Principles. Retrieved from https://rules.dnvgl.com/docs/pdf/DNVGL/RU-SHIP/2017-07/DNVGL-RU-SHIP-Pt3Ch3.pdf

DNV-GL. (2017h, Jan). Rules for Classification of Ships: Part 3, Chapter 4 - Loads.Retrieved from https://rules.dnvgl.com/docs/pdf/DNVGL/RU-SHIP/2017-07/DNVGL-RU-SHIP-Pt3Ch4.pdf

DNV-GL. (2017i, Jan). Rules for Classification of Ships: Part 3, Chapter 6 - Hull LoadScnatling. Retrieved from https://rules.dnvgl.com/docs/pdf/DNVGL/RU-SHIP/2017-07/DNVGL-RU-SHIP-Pt3Ch6.pdf

DNV-GL. (2017j, Jan). Rules for Classification of Ships: Part 3, Chapter 8 - Buckling.Retrieved from https://rules.dnvgl.com/docs/pdf/dnvgl/ru-ship/2017-01/DNVGL-RU-SHIP-Pt3Ch8.pdf

DNV-GL. (2017k). Rules for the Classification of Ships: Part 6, Chapter 8 - Livingand Working Conditions. Retrieved from https://rules.dnvgl.com/docs/pdf/DNVGL/RU-SHIP/2017-07/DNVGL-RU-SHIP-Pt6Ch8.pdf

Ellis, J. (Ed.). (2017, Jun). Methanol – an alternative fuel for shipping?Epps, B., & Kimball, R. (2013). Openprop v3: Open-source software for the design and

analysis of marine propellers and horizontal-axis turbines. Online.Ethermo Calculation Platform. (2009). Thermodynamic and transport properties. Re-

trieved from http://www.ethermo.us/Show57Vatemp!281.15!1.htm

138

http://www.imo.org/fr/OurWork/Environment/PollutionPrevention/AirPollution/Documents/Report%20Methanol%2021.01.2016.pdf

http://www.imo.org/fr/OurWork/Environment/PollutionPrevention/AirPollution/Documents/Report%20Methanol%2021.01.2016.pdf

https://rules.dnvgl.com/docs/pdf/DNVGL/RU-SHIP/2017-07/DNVGL-RU-SHIP-Pt2Ch2.pdf




https://rules.dnvgl.com/ServiceDocuments/dnvgl/#!/industry/1/Maritime/1/DNV%20GL%20rules%20for%20classification:%20Ships%20(RU-SHIP)





https://rules.dnvgl.com/docs/pdf/dnvgl/ru-ship/2017-01/DNVGL-RU-SHIP-Pt3Ch11.pdf




http://rules.dnvgl.com/docs/pdf/dnvgl/ru-ship/2017-01/DNVGL-RU-SHIP-Pt3Ch2.pdf

http://rules.dnvgl.com/docs/pdf/dnvgl/ru-ship/2017-01/DNVGL-RU-SHIP-Pt3Ch2.pdf











http://www.ethermo.us/Show57Vatemp!281.15!1.htm

References

FRIENDHSHIP SYSTEMS. (2017). CAESES. (Version 4.2) [Computer Software].Gesab. (2017, Nov). Gesab Catamizer. Retrieved from http://www.gesab.net/

catamiserGREEN4SEA. (2017). IBIA joins Trident Alliance. Retrieved from https://www

.green4sea.com/ibia-joins-trident-alliance/Haynes, D. (2015, Sep). LNG as a Marine Fuel.Herdzik, J. (2013). Evaluating Criteria for DP Vessles. KONES Powertrain and Trans-

port, 20 .IMO. (2006). Resolution MSC.216(82): Amendments to the Interational Con-

vention for the Safety of Life at Sea, 1974, as amended. Retrievedfrom http://www.imo.org/en/KnowledgeCentre/IndexofIMOResolutions/Maritime-Safety-Committee-(MSC)/Documents/MSC.281(85).pdf

IMO. (2008). Resolution MSC.267(85) - Adoption of the International Code onIntact Stability. Retrieved from http://www.imo.org/en/KnowledgeCentre/IndexofIMOResolutions/Maritime-Safety-Committee-(MSC)/Documents/MSC.267(85).pdf

IMO. (2009). Solas. London, United Kingdom: Interational Maritime Organization.IMO. (2014). Guidelines on the Method of Calculation of the Attained Energy

Efficiency Design Index (EEDI) for New Ships. IMO. Retrieved fromhttp://www.imo.org/en/OurWork/Environment/PollutionPrevention/AirPollution/Documents/245(66).pdf

IMO. (2016). Ship energy efficiency regulations and related guidelines (Vol. Train TheTrainer Course). IMO.

IMO. (2017). Nitrogen Oxides (NOx) – Regulation 13. Retrieved from http://www.imo.org/en/OurWork/environment/pollutionprevention/airpollution/pages/nitrogen-oxides-(nox)-%E2%80%93-regulation-13.aspx

IMO. (2017). Prevention of Air Pollution from Ships. Retrieved fromhttp://www.imo.org/en/OurWork/Environment/PollutionPrevention/AirPollution/Pages/Air-Pollution.aspx

IMO. (2017). Sulphur oxides (SOx) and Particulate Matter (PM) – Regula-tion 14. Retrieved from http://www.imo.org/en/OurWork/environment/pollutionprevention/airpollution/pages/sulphur-oxides-(sox)---regulation-14.aspx

International Marine Airflow. (2017). Ventilation Fan. Retrieved from https://www.marineairflow.com/marine-ac-and-dc-fans.html

ISO. (1998, May). Shipbuilding: Engine-room ventilation in diesel-engines ships: Designrequirements and basis of calculations (Tech. Rep.). Author.

Larsson, L., & Raven, H. C. (2010). The Principles of Naval Architecture Series: ShipResistance and Flow. The Society of Naval Architects and Marine Engineers.

Lewis, E. V. (1989). Principles of Naval Architecture, Volume III - Motions in Wavesand Controllability. The Society of Naval Architects and Marine Engineers.

MAN. (2011, Dec). Basic Principles of Ship Propulsion (Tech. Rep.). MAN Diesel &Turbo.

MAN. (2015a). Diesel-electric Propulsion Plants (Tech. Rep.). Author. Retrievedfrom https://marine.man.eu/docs/librariesprovider6/marine-broschures/diesel-electric-drives-guideline.pdf

MAN. (2015b). Waste Heat Recovery Unit (Tech. Rep.). Author.Retrieved from http://marine.man.eu/docs/librariesprovider6/technical

139

http://www.gesab.net/catamiser

http://www.gesab.net/catamiser

https://www.green4sea.com/ibia-joins-trident-alliance/

https://www.green4sea.com/ibia-joins-trident-alliance/

http://www.imo.org/en/KnowledgeCentre/IndexofIMOResolutions/Maritime-Safety-Committee-(MSC)/Documents/MSC.281(85).pdf





http://www.imo.org/en/OurWork/Environment/PollutionPrevention/AirPollution/Documents/245(66).pdf

http://www.imo.org/en/OurWork/Environment/PollutionPrevention/AirPollution/Documents/245(66).pdf

http://www.imo.org/en/OurWork/environment/pollutionprevention/airpollution/pages/nitrogen-oxides-(nox)-%E2%80%93-regulation-13.aspx



http://www.imo.org/en/OurWork/Environment/PollutionPrevention/AirPollution/Pages/Air-Pollution.aspx

http://www.imo.org/en/OurWork/Environment/PollutionPrevention/AirPollution/Pages/Air-Pollution.aspx

http://www.imo.org/en/OurWork/environment/pollutionprevention/airpollution/pages/sulphur-oxides-(sox)---regulation-14.aspx



https://www.marineairflow.com/marine-ac-and-dc-fans.html

https://www.marineairflow.com/marine-ac-and-dc-fans.html

https://marine.man.eu/docs/librariesprovider6/marine-broschures/diesel-electric-drives-guideline.pdf

https://marine.man.eu/docs/librariesprovider6/marine-broschures/diesel-electric-drives-guideline.pdf

http://marine.man.eu/docs/librariesprovider6/technical-papers/waste-heat-recovery-system.pdf?sfvrsn=10



References

-papers/waste-heat-recovery-system.pdf?sfvrsn=10MathWorks. (2016). MATLAB. (R2016b) [Computer Software]. (Academic License)M.Grljušić,V. Medica and G.Radica. (2015, Aug). Calculation of Efficiencies of a Ship

Power Plant Operating with Waste Heat Recovery through Combined Heat andPower Production. Energies(4273-4299; doi:10.3390/en8054273).

Molloy, N. (2016, Oct). Tme IMO’S 2020 Global Sulfur Cap. Re-trieved from https://www.platts.com/IM.Platts.Content/InsightAnalysis/IndustrySolutionPapers/SR-IMO-2020-Global-sulfur-cap-102016.pdf

NordForsk. (1987). Assessment of Ship Performance in a Seaway: The Nordic Co-operative Project: "Seakeeping Performance of Ships". Nordforsk , eksp. Skib-steknisk Laboratorium.

OCIMF. (1994). Prediction of Wind and Current Loads on VLCCs. London, England:Witherby Co. LTD.

Pablo Semolinos, G. O., & Giacosa, A. (2013). LNG as Marine Fuel: Challenges to beOvercome.

Ramne, B. (2017, Nov). Personal Communication.Ringsberg, J. W., & Thelandersson, S. (2016). Marine Structural Engineering. Gothen-

burg, Sweden: Department of Shipping and Marine Technology, Chalmers Univer-sity of Technology.

Seifert, J. (2012, Nov). A Review of the Magnus Effect in Aeronautics.Sinha, T. (2017, Sep). An Introduction to Tunnel Thrusters in Ships – Design and Appli-

cation. Retrieved from http://www.marineinsight.com/naval-architecture/introduction-to-tunnel-thrusters-ships/

Stojcevski, T. (2015). METHANOL – as Engine Fuel, Status Stena Germanica andmarket overview.

Stopford, M. (2009). Maritime Economics (3rd ed.). Routledge.The Engineering ToolBox. (2017, Dec). Air duct sizing. Retrieved from https://

www.engineeringtoolbox.com/sizing-ducts-d_207.htmlThe Engineering Toolbox. (2017a). Flash Point-Fuels. Retrieved from https://www

.engineeringtoolbox.com/flash-point-fuels-d_937.htmlThe Engineering Toolbox. (2017b). Higher Calorific Values. Retrieved from https://

www.engineeringtoolbox.com/fuels-higher-calorific-values-d_169.htmlThe International Marine Contractors Association. (2000). IMCA M 140 Rev. I: Specifi-

cation for DP Capability Plots. Online. Retrieved from https://eti.pg.edu.pl/documents/176634/32506864/imcam140.pdf

TTS Port Equipment AB. (2017a). Cassette (Tech. Rep.). TTS Marine.Retrieved from http://www.ttsgroup.com/Global/Cassette%20system%20for%20container%20terminals.pdf

TTS Port Equipment AB. (2017b). Cassette Systems for Container Terminals(Tech. Rep.). TTS Marine. Retrieved from http://www.ttsgroup.com/Global/CasetteSystems_ContainerTerminals_v4.pdf?epslanguage=en

TTS Port Equipment AB. (2017c). C-AVG (Tech. Rep.). TTS marine. Retrieved fromhttp://www.ttsgroup.com/Global/C-AGV.pdf?epslanguage=en

van Lammeren, W., Manen, D., Oosterveld, M., & Basin, N. S. M. (1969). TheWageningen B-screw Series. Netherlands Ship Model Basin. Retrieved fromhttps://books.google.se/books?id=qjwlmwEACAAJ

Verkerk, F. (2002). Manoeuvring Aspects of Vessels Equipped with Pods. MaritimeResearch Institute Netherlands.

140




https://www.platts.com/IM.Platts.Content/InsightAnalysis/IndustrySolutionPapers/SR-IMO-2020-Global-sulfur-cap-102016.pdf

https://www.platts.com/IM.Platts.Content/InsightAnalysis/IndustrySolutionPapers/SR-IMO-2020-Global-sulfur-cap-102016.pdf

http://www.marineinsight.com/naval-architecture/introduction-to-tunnel-thrusters-ships/

http://www.marineinsight.com/naval-architecture/introduction-to-tunnel-thrusters-ships/

https://www.engineeringtoolbox.com/sizing-ducts-d_207.html

https://www.engineeringtoolbox.com/sizing-ducts-d_207.html

https://www.engineeringtoolbox.com/flash-point-fuels-d_937.html

https://www.engineeringtoolbox.com/flash-point-fuels-d_937.html

https://www.engineeringtoolbox.com/fuels-higher-calorific-values-d_169.html

https://www.engineeringtoolbox.com/fuels-higher-calorific-values-d_169.html

https://eti.pg.edu.pl/documents/176634/32506864/imcam140.pdf

https://eti.pg.edu.pl/documents/176634/32506864/imcam140.pdf

http://www.ttsgroup.com/Global/Cassette%20system%20for%20container%20terminals.pdf

http://www.ttsgroup.com/Global/Cassette%20system%20for%20container%20terminals.pdf

http://www.ttsgroup.com/Global/CasetteSystems_ContainerTerminals_v4.pdf?epslanguage=en

http://www.ttsgroup.com/Global/CasetteSystems_ContainerTerminals_v4.pdf?epslanguage=en

http://www.ttsgroup.com/Global/C-AGV.pdf?epslanguage=en

https://books.google.se/books?id=qjwlmwEACAAJ

References

Vossen, C., Kleppe, R., & Hjørungnes, R. (2013, Dec). Ship Design and System Integra-tion. , 13.

Wankhede, A. (2017). General Overview of Central Cooling System on Ships. Re-trieved from https://www.marineinsight.com/guidelines/general-overview-of-central-cooling-system-on-ships/

Wärtsilä. (2015). Wärtsilä Environmental Product Guide (Tech. Rep.). Wärt-silä. Retrieved from https://cdn.wartsila.com/docs/default-source/product-files/egc/product-guide-o-env-environmental-solutions.pdf?sfvrsn=20

Wärtsilä. (2017a). Ballast Water Management. Retrieved from https://www.wartsila.com/products/marine-oil-gas/ballast-water

Wärtsilä. (2017b). Waste and Fresh Water Management. Retrieved fromhttps://cdn.wartsila.com/docs/default-source/product-files/water/fresh/brochure-o-water-fresh-generators.pdf?sfvrsn=ec3de945_4

Wärtsilä. (2017c). Wärtsilä 20D - Product Guide [Computer software man-ual]. Retrieved from https://cdn.wartsila.com/docs/default-source/product-files/engines/ms-engine/product-guide-o-e-w20.pdf?sfvrsn=6

Wärtsilä. (2017d). Wärtsilä 31D - Product Guide [Computer software man-ual]. Retrieved from https://cdn.wartsila.com/docs/default-source/product-files/engines/ms-engine/product-guide-o-e-w31.pdf?sfvrsn=4

Wärtsilä. (2017e). Wärtsilä Aquarius® EC BWMS. Retrieved fromhttps://www.wartsila.com/products/marine-oil-gas/ballast-water/bwms/wartsila-aquarius-ec-bwms

Wärtsilä. (2017f). Wärtsilä HY - The First Integrated Hybrid Power Mod-ule in the Marine Industry [Computer software manual]. Retrieved fromhttps://cdn.wartsila.com/docs/default-source/product-files/hybrid/brochure-o-ea-hy.pdf?sfvrsn=62d29045_6

Ådnanes, A. K. (2010). Energy Efficiency and Fuel Consumption of Marine and Off-shore Vessels (Tech. Rep.). ABB. Retrieved from http://www02.abb.com/global/seitp/seitp202.nsf/0/e1e06068666a4ed1c12577fb00073e9d/\protect\T1\textdollarfile/Electric+Distribution.pdf

141

https://www.marineinsight.com/guidelines/general-overview-of-central-cooling-system-on-ships/

https://www.marineinsight.com/guidelines/general-overview-of-central-cooling-system-on-ships/

https://cdn.wartsila.com/docs/default-source/product-files/egc/product-guide-o-env-environmental-solutions.pdf?sfvrsn=20



https://www.wartsila.com/products/marine-oil-gas/ballast-water

https://www.wartsila.com/products/marine-oil-gas/ballast-water

https://cdn.wartsila.com/docs/default-source/product-files/water/fresh/brochure-o-water-fresh-generators.pdf?sfvrsn=ec3de945_4

https://cdn.wartsila.com/docs/default-source/product-files/water/fresh/brochure-o-water-fresh-generators.pdf?sfvrsn=ec3de945_4

https://cdn.wartsila.com/docs/default-source/product-files/engines/ms-engine/product-guide-o-e-w20.pdf?sfvrsn=6




https://www.wartsila.com/products/marine-oil-gas/ballast-water/bwms/wartsila-aquarius-ec-bwms

https://www.wartsila.com/products/marine-oil-gas/ballast-water/bwms/wartsila-aquarius-ec-bwms

https://cdn.wartsila.com/docs/default-source/product-files/hybrid/brochure-o-ea-hy.pdf?sfvrsn=62d29045_6

https://cdn.wartsila.com/docs/default-source/product-files/hybrid/brochure-o-ea-hy.pdf?sfvrsn=62d29045_6

http://www02.abb.com/global/seitp/seitp202.nsf/0/e1e06068666a4ed1c12577fb00073e9d/\protect \T1\textdollar file/Electric+Distribution.pdf



References

142

Appendix A - Tables

Appendix Tables List

A.1 Fire integrity of all bulkheads and decksA.2 Wave scatter diagramA.3 Electrical balance

I

Appendix

A-Tables

Table A.1: Minimum fire integrity of all bulkheads and decks (IMO, 2009)

Space (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

Control Station (1) A-0e A-0 A-60 A-0 A-15 A-60 A-15 A-60 A-60 * A-60Corridors (2) C B-0 B-0 A-0c B-0 A-60 A-0 A-0 A-0 * A-30Accommodation space (3) Ca,b B-0 A-0c B-0 A-60 A-0 A-0 A-0 * A-30Stairways (4) B-0 A-0c B-0 A-0c A-60 A-0 A-0 A-0 * A-30Service spaces (low risk) (5) C A-60 A-0 A-0 A-0 * A-0Machinery spaces of category A (6) * A-0 A-0g A-60 * A-60f

Other machinery spaces (7) A-0 A-0 A-0 * A-0Cargo space (8) * A-0 * A-0Service space (high risk) (9) A-0d * A-30Open decks (10) - A-0RORO and vehicle spaces (11) ∗

a Consult paragraphs 2.2.2 and 2.2.5 (IMO, 2009).b Where spaces are of the same numerical category and superscript “b” appears, a bulkhead or deck of the rating shown inthe tables is only required when the adjacent spaces are for a different purpose. A galley next to a galley does not requirea bulkhead, but a galley next to a paint room requires an “A-0” bulkhead.c Bulkheads separating the wheelhouse and chartroom from each other may have a “B-0” rating.d Consult paragraphs 2.2.4.2.3 and 2.2.4.2.4 (IMO, 2009).f For the application of paragraph 2.2.1.1.2, “B-0” and “C”, shall be read as “A-0” (IMO, 2009).∗ The division is required to be of steel or other equivalent material, but is not required to be of “A” class standard. However,where a deck, except in a category (10) space, is penetrated for the passage of electric cables, pipes and vent ducts, suchpenetrations shall be made tight to prevent the passage of flame and smoke. Divisions between control stations (emergencygenerators) and open decks may have air intake openings without means for closure, unless a fixed gas fire extinguishingsystem is fitted. For the application of paragraph 2.2.1.1.2, an asterisk, where appearing in table 9.4, except for categories(8) and (10), shall be read as “A-0” (IMO, 2009).

II

Appendix

A-Tables

Table A.2: Wave scatter diagram for the operating area (ABB, 2017)

Tz [s] 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 14 14.5 15 15.5 16 16.5 17Hs [m] Sum

17 016.5 016 0.1 0.1 0.1 0.315.5 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.715 0.1 0.1 0.1 0.1 0.2 0.2 0.1 0.1 0.1 0.1 1.214.5 0.1 0.1 0.2 0.2 0.3 0.3 0.3 0.2 0.2 0.1 0.1 0.1 2.214 0.1 0.2 0.3 0.4 0.4 0.5 0.4 0.4 0.3 0.2 0.2 0.1 0.1 3.613.5 0.1 0.2 0.3 0.5 0.6 0.7 0.7 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.1 613 0.1 0.2 0.3 0.6 0.8 1.1 1.2 1.2 1.1 0.9 0.7 0.5 0.4 0.2 0.2 0.1 0.1 9.712.5 0.1 0.1 0.3 0.6 1 1.4 1.8 2 1.9 1.8 1.5 1.1 0.8 0.6 0.4 0.2 0.1 0.1 15.812 0.1 0.3 0.6 1.1 1.7 2.4 2.9 3.1 3.1 2.7 2.2 1.7 1.2 0.8 0.5 0.3 0.2 0.1 0.1 25.111.5 0.1 0.2 0.5 1 1.9 2.9 4 4.7 5 4.8 4.1 3.3 2.5 1.7 1.2 0.7 0.4 0.3 0.1 0.1 39.511 0.1 0.4 0.9 1.8 3.2 4.9 6.5 7.5 7.8 7.3 6.2 4.9 3.6 2.5 1.6 1 0.6 0.3 0.2 0.1 0.1 61.510.5 0.1 0.3 0.7 1.6 3.2 5.5 8.1 10.4 11.8 12 10.9 9.1 7.1 5.1 3.4 2.2 1.4 0.8 0.5 0.2 0.1 0.1 94.610 0.2 0.5 1.3 2.9 5.6 9.2 13.2 16.5 18.3 18 16.1 13.2 10 7.1 4.7 3 1.8 1 0.6 0.3 0.2 0.1 143.89.5 0.1 0.3 1 2.4 5.2 9.6 15.3 21.2 25.8 27.7 26.7 23.3 18.7 13.9 9.6 6.3 3.9 2.3 1.3 0.7 0.4 0.2 0.1 0.1 216.19 0.2 0.7 1.9 4.4 9.1 16.1 24.9 33.5 39.5 41.3 38.8 33.1 25.9 18.8 12.8 8.2 5 2.9 1.6 0.9 0.5 0.2 0.1 0.1 320.58.5 0.1 0.4 1.3 3.5 7.9 15.6 26.8 39.9 51.9 59.4 60.4 55.2 45.9 35 24.9 16.5 10.4 6.2 3.5 2 1 0.5 0.3 0.1 0.1 468.88 0.2 0.8 2.5 6.4 14 26.5 43.7 62.8 79 87.5 86.3 76.7 62.1 46.3 32.1 20.8 12.8 7.5 4.2 2.3 1.2 0.6 0.3 0.1 0.1 676.87.5 0.1 0.4 1.6 4.8 11.7 24.3 44.2 70.1 97 117.7 126.2 120.6 104 81.9 59.4 40.2 25.5 15.4 8.8 4.8 2.6 1.3 0.7 0.3 0.2 0.1 963.97 0.2 0.9 3.2 9 20.9 41.6 72.4 110.2 146.8 171.6 177.6 164.3 137.4 105 74.2 48.9 30.3 17.8 10 5.4 2.8 1.4 0.7 0.3 0.2 0.1 1353.26.5 0.4 1.8 6.3 16.7 36.7 69.8 116.2 169.7 217 244.2 243.6 217.6 176.1 130.5 89.5 57.4 34.6 19.9 10.9 5.7 2.9 1.5 0.7 0.3 0.2 0.1 1870.36 0.1 0.9 3.8 12.2 30.3 63.4 114.9 182.8 255.3 313 338.1 324.5 279.5 218.5 156.7 104.2 64.9 38.1 21.3 11.4 5.9 2.9 1.4 0.7 0.3 0.1 0.1 2545.35.5 0.3 1.9 7.9 23.2 54.3 107.4 185.2 280.8 374.5 438.9 454.2 418.3 346.6 261.1 180.9 116.4 70.2 40 21.7 11.3 5.7 2.8 1.3 0.6 0.3 0.1 0.1 34065 0.1 0.7 4.3 15.9 43.4 95.3 178.1 291.4 420.2 533.6 596.4 589.5 519.7 413 299.1 199.6 123.9 72.3 39.9 21 10.7 5.2 2.5 1.1 0.5 0.2 0.1 4477.74.5 0.2 1.8 9.4 31.7 79.8 163.6 288.1 446.2 610.2 735.4 781.2 735.2 618.3 469.7 326 208.9 124.8 70.2 37.5 19.1 9.4 4.5 2.1 0.9 0.4 0.2 0.1 5774.94 0.5 4.5 20.4 62 143.4 274 453.5 662.4 855.8 975.1 980.3 874.6 698.8 505.5 334.8 205.2 117.6 63.5 32.6 16.1 7.6 3.5 1.6 0.7 0.3 0.1 0.1 7294.53.5 0.1 1.5 10.8 43.4 118.7 251.3 445.9 690.7 947.8 1151.2 1233.6 1167.7 982.5 741.9 508.4 319.8 186.6 102.1 52.8 26 12.3 5.6 2.5 1.1 0.5 0.2 0.1 9005.13 0.3 4.3 25.8 90.5 221.5 427.6 701 1011.3 1296 1470.6 1472.3 1302.9 1026.6 727.6 469.3 278.5 153.8 79.8 39.2 18.4 8.3 3.6 1.6 0.7 0.3 0.1 10831.92.5 1.1 12.1 61.1 184.9 401 700.7 1055.1 1408.2 1672.2 1756.9 1627.7 1333.9 974.8 642.4 386.3 214.5 111.1 54.2 25.2 11.2 4.8 2 0.8 0.3 0.1 0.1 12642.72 0.1 4 34.4 142.5 366.7 696.9 1092.9 1498.3 1831.7 1991.9 1912.3 1616.7 1209.5 808.5 488.7 270.5 138.7 66.6 30.2 13.1 5.5 2.2 0.9 0.3 0.1 14223.21.5 0.8 15.1 98.8 325.8 696.6 1141.8 1585.7 1953.1 2151.8 2101.3 1803.4 1360 908 542.9 294.6 147 68.2 29.8 12.4 4.9 1.9 0.7 0.3 0.1 152451 0.1 3.8 47.6 219.3 536.1 875.1 1110.7 1203.5 1166.3 1021.9 803.6 563 351.2 196.5 99.7 46.4 20.1 8.2 3.2 1.2 0.4 0.1 0.1 8278.1Sum 0.1 4.7 68.2 371.2 1109.5 2294.8 3815.3 5576.3 7472.8 9289.2 10680.1 11302.8 10994.4 9854.2 8178.8 6323.9 4583.6 3133 2031.4 1255.8 744.3 424.3 234.1 125.6 65.3 33.3 16.5 8.1 3.7 1.8 0.9 99998

III

Appendix

A-Tables

Table A.3: Electric balance

Baseline OpenWater

DPAnchor Unloading Port Ma-

noeuvre Harbour Emergency

[kW] [kW] [kW] [kW] [kW] [kW] [kW]

Main Engine 11330Aux Engine 2280Battery Storage 1005Waste Heat Recovery Unit 679,8

Total 15294,8On Board System

40 ManoeuvringAzipods 5585 5585 838 838 1675 0 0Thrusters 2200 0 2200 2200 1100 0 0

30 Hatches and Ports 200 0 0 200 0 0 032 Special Cargo Handling 200 0 0 200 0 0 033 Deck Cranes 700 0 0 700 0 0 035 Loading/Unloading System 350 0 0 350 0 0 041 Navigation 15 15 15 15 15 15 1542 Communication 12 12 12 12 12 12 1244 Anchoring and Mooring 65 0 65 65 0 65 050 Life Saving 100 0 0 0 0 0 10054 Furniture/Lights 40 40 40 40 40 40 655 Galley and Laundry 38 38 38 38 38 38 057 HVAC 300 300 300 300 300 300 4558 Sanitary 38 38 38 38 38 38 3863 Transmission and Foils 10 10 10 10 10 10 10

IV

Appendix

A-Tables

Baseline OpenWater

DPAnchor Unloading Port Ma-

noeuvre Harbour Emergency

[kW] [kW] [kW] [kW] [kW] [kW] [kW]

70 Fuel Oil Systems 104 104 52 72,8 31,2 20,8 15,671 Lube Oil Systems 48 48 24 33,6 14,4 9,6 7,272 Cooling Systems 100 100 50 70 30 20 1573 Compressed Air Systems 41 41 20,5 28,7 12,3 8,2 6,1574 Exhaust Systems 290 290 145 203 87 58 43,575 Steam and Feed Water 50 50 25 35 15 10 7,580 Ballast and Bilge 1076 1076 1076 1076 1076 0 081 Firefighting and Alarms 150 0 0 0 0 0 150

SUM 11712 7747 4948 6525 4494 645 47115% Margin 13468 8908 5690 7503 5168 741 542Available Engine power 13610 10208 5104 8498 5104 855 760WHRU 817 612 306 613 306 0 0Total Power Provided 10820 6410 9110 5410 855 760

Configuration2M(75) 1

2 2A(75) 3

B 4 W 5

1M(75) WB

2M(75) WB

1M(75)1A(75) W

B

1A(75) orB

E(100) 6

or B

Difference [%] 18 11 18 4 13 29

1( ) MCR2M - Main Engine3A - Auxiliary Engine4B - Battery Unit5W - Waste Heat Recovery6E - Emergency Generator

V

Appendix A - Tables

VI

Appendix B - Drawings

Appendix Drawings List

MPD2017_1 - 101-01-02 - General ArrangementMPD2017_1 - 101-02-01 - Lines PlanMPD2017_1 - 101-03-01 - Tank ArrangementMPD2017_1 - 101-16-01 - Instalment ArrayMPD2017_1 - 200-05-01 - Midship SectionMPD2017_1 - 310-01-01 - Cargo Handling OperationsMPD2017_1 - 501-01-01 - Safety and Fire PlanMPD2017_1 - 510-01-01 - Accommodation ArrangementMPD2017_1 - 600-01-01 - Engine Room ArrangementMPD2017_1 - 701-01-01 - Fuel SystemMPD2017_1 - 722-02-01 - Cooling SystemMPD2017_1 - 740-01-01 - Steam and Power Turbine WHR SystemMPD2017_1 - 801-01-01 - Ballast Treatment

VII

A

DOWN

DOWN

FIRE/SAFETY

PLAN

MUSTER

LIST

DOWN

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DOWN

UP

FIRE/SAFETY

PLAN

A

1

UP

UP

UP

UP

UP

FIRE/SAFETY

PLAN

AUP

UP

UP

UP

UP

FIRE/SAFETY

PLAN

A

1

FIRE/SAFETY

PLAN

MUSTER

LIST

UP

UP

UP

UPUP

UPUP

UPUP

UP

UPUP

UP

UP

UP

UP

UP

UP

ME

MEME

ME

ME

ME

ME

ME

ME

ME

Mehtnah