marin report 102

M ARIN ’s news magaz ine fo r the mar i t ime indus t r yApr i l 2011 no. 102

Deepwater pit proves popular for TLP model tests Valuable training on LNG Floating Storage and Regasification Unit Complex coupled model tests for Petrobras

oFFShoRe

SPEC

IAL

Mark Randall, Swire Pacific offshore

World-class Anchor Handling Simulator

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editorial

colophonreport is a news magazine of MARINHaagsteeg 2, P.O.Box 286700 AA Wageningen, The Netherlands P +31 317 49 39 11F +31 317 49 32 45Printing 5,500

editorial Board Bas Buchner, Henk van den Boom, Ellen te Winkel ([email protected])

editorial consultant Helen Hill

Design & Production Verheul CommunicatieAlphen aan den Rijn, The Netherlands

Cover Screen shot of Anchor Handling Simulator

The editorial staff has made every attempt to ensure the accuracy of the contents. However, experience has shown that, despite the best intentions, occasional errors might have crept in. MARIN cannot, therefore, accept responsibility for these errors or their consequences. For remarks or questions, please contact Ellen te Winkel. E-mail: [email protected]

For subscription to MARIN Report or cancellation, please visit www.marin.nl/MARINReport.htm.

6 MARIN, MPRI and Swire Pacific Offshore (SPO) develop a world-class deepwater Anchor Handling Simulator

Report interviews Captain Mark Randall, Project Manager of the Swire Marine Training Centre (SMTC) in Singapore about whether the simulator has lived up to expectations.

9 June 2011: 30th OMAE Conference & the Floating Wind Turbine Challenge!

10 Deepwater pit proves popular for TLP model tests We delve the inner depths of the deepwater pit and examine these challenging projects.

12 Valuable training on LNG Floating Storage and Regasification Unit

MARIN’s Full Mission Bridge simulators provided simulation training for what is believed to be the world’s first FSRU installed offshore.

14 Complex coupled model tests for Petrobras Model tests were carried out simultaneously on three floaters in MARIN’s Offshore Basin.

The complexities of this test programme are unravelled for the first time.

16 Increasing interest in tests for Vortex Induced Motions Report highlights the latest VIM tests.

18 MARIN has the wind in its sails With the growth in renewable energy, there is an increasing focus on offshore wind.

MARIN is actively participating in the development of the offshore wind energy sector.

20 Managing fatigue in riser systems Report puts the new MonaRisa Joint Industry Project in the spotlight.

21 CrackGuard – it’s all in the name! A new JIP will help ensure the structural integrity of marine structures. Report cracks the

case open.

22 L&R study for new GOWIND OPV DCNS chose MARIN to conduct an operability study of the Launch and Recovery system

to be installed on the new GOWIND type Offshore Patrol Vessels.

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Dear Reader,

Welcome to this Report. As this is my first edition at the helm of MARIN, I will introduce myself in a few lines to those of you who don’t know me yet.

I am a naval architect by training and have always been fascinated by everything that sails and floats. Based on this fascination I did my PhD on the in-triguing subject of ‘green water loading’, alongside my work as the manager of MARIN’s Offshore De-partment. I share the enthusiasm of all my MARIN colleagues for extending the boundaries of our knowledge and indeed, we think we need to do this to assist you with your problems and innovations.

The other thing that fascinates me in this respect is technical progress through cooperation. An open dialogue and cooperation with clients and research partners is very important. Our future challenges are simply too complex to be solved alone.

With this special offshore edition we hope to share some of the latest progress and projects. And we have a interesting interview with Swire Pacific Offshore about its world-class, deepwater Anchor Handling Simulator.

As part of our commitment to cooperation, MARIN is busy organising the OMAE 2011 conference, together with the Dutch offshore industry and OMAE. Together with INORE we have organised a special design and build contest, the “Floating Wind Turbine Challenge”. You can find out more in this issue.

And of course, MARIN is present at the OTC. This year we will be there with a demo model of our deepwater Anchor Handling Simulator. I would encourage you to come along to our OTC stand and take a chance to try your skills on the simulator. And you are most welcome for a drink on Tuesday May 3, 16.00 hrs.

I look forward to meeting you personally at OTC, OMAE or at MARIN!

Bas BuchnerPresident

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newsnews

oTC 2011 - May 2-5MARIN will again attend OTC in Houston. Meet us at the Dutch Pavilion (stand 2517) and train your Anchor Handling skills! On Tuesday May 3, 16.00 hrs you are most welcome to join us for drinks and shake hands with our new President Bas Buchner.

C&SI - May 10-12MARIN will be present at “Construction & Shipping Industry” in Gorinchem, the Netherlands. Visit us at stand 326 to discuss the latest technologies we offer the inland shipping industry and find out how you can save fuel and reduce CO2 emissions just by a few clicks.

Nor-Shipping - May 24-27You can again meet us at Nor-Shipping in Oslo. We would like to welcome you at stand C02-18a within the Dutch Pavilion of HME (Hall C).

harsh Weather SummitMay 31 & June 1

More than 170 attendees at 26th FPSo Forum & JIP Week From March 21 to 25 SBM Offshore hosted the 26th FPSO Forum & JIP Week in Mona-co. With more than 170 attendees the event continued to attract all stakeholders in the FPSO industry; all major oil compa-nies, FPSO operators, engineering contrac-tors, class societies and R&D organizations were present. In total ten Joint Industry Projects had their progress meetings and three new JIPs had open meetings.

Theme of this year’s Open Forum was “Re-allocation & Life Time Extension” with excellent presentations by SBM, Petrobras, Bluewater and several others. During this forum also three JIP initiatives were presented.

MARIN launched three new JIP’s:

MONARISAThe initiative concerns integrity monitoring of rigid and steel catenary risers. Utilizing the approach developed for FPSO hulls in the MONITAS JIP, the focus in this project is the processing of data from a minimum monitoring system to obtain meaningful data on the integrity and fatigue lifetime of the riser. For the develop-ment preferably use will be made of an

riser which is already instrumented. The proposal is currently in preparation and your input is highly valued. Contact [email protected]

OFFLOADING OPERABILITY IIIPhase I and II of this JIP were successfully completed and concerned model testing

and the development of computational simulation tool SHUTTLE, both for tandem and side-by side offloading of oil and gas. In phase III the focus is on in-situ measure-ments for validation of the numerical results. Contact [email protected]

HELIOSThis JIP is aiming at improving both safety and workability of helicopter operations on offshore vessels. Existing practice to fly to moving heli-decks is based on strict limita-tions on heli-deck inclinations and heave rate over the last 20 minutes. This strict regime leads to a low workability for small vessels and harsh weather regions but is not necessarily safe as accelerations and wind are not included and the prediction of maximum motions are based on the 20 mins. history. HELIOS JIP saw her lift-off meeting on March 22 and is still open for new participants. Contact [email protected]

The 27th FPSO JIP Week will be hosted by DNV in their new offices in Houston from October 24-28, 2011. For further informa-tion please visit www.fpsoforum.com

The European Council of Maritime Applied R&D is pleased to announce the appointment of Mr Graham Clarke as its new Director, in success to Dr Tony Morrall, with effect from February 2011. Graham is a graduate naval architect, who has worked in both large and small maritime businesses for over 40 years, involved with manufacturing and research aspects of the sector.Founded in 2006, ECMAR is an associa-

tion of around 30 applied research organi-sations, from 14 European countries, where their primary focus is on commercial activities. A key ECMAR function is to make the link between basic research, undertaken by universities, and its use by industry, in which role, ECMAR members have exten-sive experience of technology transfer for exploitation. ECMAR members undertake a great deal of leading-edge research and investigation work, not least from their

extensive hydrodynamic testing facili-ties, amongst the most advanced in the world. ECMAR acts as an interface with other networks and with the European Commission and provides facilitation and support for its members in partici-pating in EU research projects. For more details see www.ecmar.eu

eCMAR Appoints New Director

papersMARIN offers a wide selection of papers and doctoral theses in the field of hydrodynamics on its website at www.marin.nl.

The most recent publications include:

Free-surface viscous flow solution methods for ship hydrodynamicsWackers, J., Koren, B., Raven, H.C., Van der Ploeg, A., Starke, A.R., Deng, G.B., Queutey, P., Visonneau, M., Hino, T. and Ohashi, K., Archives of Computa-tional Methods in Engineering, March 2011

Calculation of bottom clearance effects on Walrus submarine hydrodynamicsBettle, M.C., Toxopeus, S.L. and Gerber, A.G., International Shipbuilding Progress, December 2010

Validation of an approach to analyse and understand ship wave makingRaven, H.C., Journal of Marine Science and Technology, December 2010

The 5th Harsh Weather Summit in Maastricht, the Netherlands, has been organised by EnergyWise. The theme this year is “Discovering the next Arctic frontiers: from the Yamal Peninsula to the Chukchi Sea”. Meet us at the conference where Henk van den Boom will give a presentation on Helicopter operations on offshore vessels in harsh weather, or visit us at our stand.

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A s the search for oil and gas goes into ever-deeper, more challeng-ing waters, the need for safe

Anchor Handling operations becomes even more pressing. In a unique long-term part-nership, MARIN, MPRI and SPO embarked on a project to develop a world-class Anchor Handling Simulator with deepwater functionality.

In the last 15 years there has been aggres-sive exploration into deeper waters as most of the easier-to-exploit offshore hydrocarbon

fields have been found and developed. With depths of up to 2,000 m, deepwater technology is the way forward and with the need to deploy anchors within an accuracy of 50 m or less, a highly skilled and trained crew is essential.

For SPO, an Anchor Handling simulator was a vital piece of equipment given the short-age of experienced offshore seafarers. One of the larger challenges facing the industry is the ability to recruit, train and retain seafaring staff, Captain Randall says. “The IMO has estimated that there will be a worldwide shortage of 45,000 seafarers by 2015 and even this appears conserva-tive. The picture in the specialised offshore sector is even more acute.”

On-the-job training increasingly difficult Prior to the establishment of SMTC nearly four years ago, offshore-specific skills were nearly entirely learned on-the-job. But with the increasing activity of the SPO fleet, the ever increasing rule and regulation-driven administrative workload pressures on the bridge and significant advances in tech-nology, relying on that traditional method

was less and less sustainable, particularly when it came to bridge management and Anchor Handling operations.

Therefore, in February 2007 SPO issued a Request for Proposal (RFP) for an Integrated Anchor Handling Vessel Simulation System. “Due to the highly specialised nature of this requirement, the RFP was only made available to a select shortlist,” says Captain Randall.

MARIN teamed up with MPRI, leveraging MPRI’s training experience and engine room simulators with MARIN’s technical solutions for bridge simulation and Anchor Handling capability. Although the specific simulation setup at its centre is the property of SPO, MARIN is able to use the underlying software it developed to meet third parties needs.

MARIN’s proposal for SPO was based on its existing Mermaid 500 vessel simulation system from MSCN that SPO had already evaluated during a visit to the Port of London Authority. However, to meet SPO’s specific requirements, MARIN needed to develop a new, higher level of simulator functionality.

Another key component that MARIN was responsible for was the integration of the Dynamic Positioning (DP) equipment - that was supplied by Converteam (formerly Alstom) - into the integrated bridge/engine room simulation environments.

Behavioural realism vital “Phase I” of the project was in essence the beginnings of developing a world-class marine training facility. But SPO and MARIN faced a signifi-cant technical challenge.

Having a diverse fleet of vessels, currently ranging from 4,000 hp to 12,000 hp, fulfilling a variety of operational roles, the simulator would need to be similarly flexible in providing a range of training outcomes. To meet this requirement MARIN has devel-oped a range of own ship models, based on seven classes of SPO vessels. A full mission (360 degree view) and half mission (135 degree view) bridge were constructed.

In addition, a full engine control room was built that was able to be fully integrated to either of the bridge simulators providing a realistic training environment. Software

development was extensive, with capabilities being developed that are unique to SMTC.

Captain Randall says the primary challenge for SPO was to develop a level of simulated Anchor Handling capability that could ade-quately substitute for traditional, on-the-job skills development. “To be credible in doing this, the degree of behavioural realism of the system needed to be of a sufficiently high level to avoid potential resistance from seasoned and experienced Anchor Handling personnel.”

Phase II - Composite mooring and deepwater Anchor Handling Captain Randall explains: “Because of the nature of the industry and the need to ensure the necessary competencies, marine training will be subject to continual development. From being able to effect training with simple mooring wires it will be necessary to train students in handling chain, synthetic and composite mooring systems. New vessels will be fitted as standard with equipment and new technologies and systems that are continually being developed to facilitate anchor handling operations in ever deeper

MARIN, MPRI and Swire Pacific Offshore (SPO) develop together

World-class deepwater Anchor handling Simulator

Report interviews Captain

Mark Randall, Project

Manager of the Swire

Marine Training Centre

(SMTC) in Singapore, about

whether the simulator has

lived up to expectations.

Mark Randall

8 repor t 9repor t

waters, such as side rail cranes and anchor recovery frames, and so simulation of these must be added to the current capabilities of the simulation system.”

As the industry moves to deeper water there is a requirement for SPO to invest in vessels capable of operating in this sector, he adds. The first four of a new, 225t bollard pull “D-Class”, the first of what will undoubtedly be a succession of deepwater capable vessels, are now under construction. These vessels, which are the largest and most powerful ever built by SPO are planned for delivery from January 2012.

“The intent of ‘Phase II’ of the current upgrade programme is to ensure that the SMTC is able to familiarise Swire crews on this new class of vessels well in advance of their delivery.

“Deepwater training brings with it additional challenges and will place demands on the system, both from a hardware and software perspective that were not foreseen or tech-nically possible to simulate at the inception phase”, he adds. “Deepwater training and simulation will involve visualisation and

handling of chain and composites not currently within the original capabilities of the existing simulator. The calculations of weights and tensions by the system will well exceed the processing capability of the initial fit out of PCs, so the core processing PCs were upgraded at the end of 2010.

“The nature of the deep and ultra deepwater scenarios is such that rarely will a single vessel be able to deal with the tensions and loads, and so generally these activities will require multiple vessels. Simulated combined exercises in which two vessels operate on the same mooring line together in a single exercise is another area where the initial simulator design was incapable of delivering a satisfactory and stable performance.” These are aspects that will be addressed by the partners as Phase II progresses.

Powerful teaching aid Since training commenced in June 2007, the SMTC has achieved all anticipated objectives. The ability to ‘fly under water’ (standard with MARIN’s simulator) and demonstrate to students what is happening beneath the

surface has proven itself as an especially powerful teaching aid.

“SMTC is now one of the very few training centres in the world where DP training can be carried out in a full mission environment. Rather than sit at a PC or DP control station in a classroom, Swire crews can be trained on the bridge of a vessel modelled exactly on those in its own fleet, significantly enhancing the degree of realism. “The centre assists in demonstrating to clients and customers how the company seeks to continually enhance the competence of its staff through the provision of (solely) discre-tionary training courses for its own seafarers. SMTC demonstrates the company’s commit-ment to being a preferred and quality employer and it brings staff together, strengthens morale and significantly improves the safety training and culture.”

Captain Randall is in no doubt that the new training centre is already a highly valued addition to the company and he looks for-ward to working with MARIN on Phase II of the project, and beyond.

This enthusiastic group of youngsters are organising many interesting events such as the welcome reception and a tour through Rotterdam harbour and there will be a lot of extra activities planned outside of the con-ference programme. To enjoy this interest-ing conference and to have a chance to visit the Dutch offshore industry and experience the Netherlands in summertime, we would like to invite you to join OMAE 2011 (www.omae2011.com).

During the OMAE week technical tours will be organised to IHC shipyards and MARIN. To complement the technical sessions of the 30th OMAE in Rotterdam, MARIN and the International Network on Offshore Renewable Energy (INORE), have organised a design and build contest, the “Floating Wind Turbine Challenge”. This challenge consists of developing and testing a small-scale, floating structure for a wind turbine in 24 hours! Small teams of students and young researchers will make their floating turbines on-the-spot and then their scaled models will be tested in the

Shallow Water basin of MARIN. During the MARIN technical visit, on the last day of the OMAE, the winning design of the Floating Wind Turbine Challenge will be announced and visitors will be able to see the contest entrants test their designs.

INORE brings together young researchers from around the world to meet, collaborate and share knowledge on renewable energy. Spurred on by the conviction that shipbuild-ing and offshore knowledge can be applied to new technology in offshore renewable energy, MARIN formed the Renewable Energy Team (RENT) in mid-2009. Members of this RENT team soon came across INORE’s representatives at conferences and they were very impressed with the level of enthusiasm and dynamism of INORE. It is very gratifying that MARIN has found a good partner in INORE to contribute to the long-term development of offshore renewable energy.

Competition registration is via the INORE website

at www.inore.org/events/fwtchallenge.

In January 2010,

MARIN already started its

efforts to organise the

OMAE 2011 conference,

together with the Dutch

offshore industry. A group

of around 30 young engi-

neers from various Dutch

offshore companies have

volunteered their services

to ensure that the upcom-

ing OMAE is a dynamic

and stimulating event.

June 2011: 30th oMAe Conference & the Floating Wind Turbine Challenge

Olaf Waals & Sebastien Gueydon

[email protected]

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Jorrit-Jan Serraris,

Eelco Frickel &

Jule Scharnke

[email protected]

F ull depth modelling is crucial to represent the set-down and related airgap decrease of the TLP correctly.

In 2010, the deepwater pit was used inten-sively for several TLP projects.

SHELL is considering a TLP for the Ormen Lange future compression development offshore Norway, in an 850 m water depth. In January 2010, model tests investigated the hydrodynamic behaviour of the platform in operational, extreme and survival condi-tions. Basin waves were generated with two different methods, denoted as random phase (RP) and random coefficient (RC). The application of RC-waves in the Offshore Basin was one of the techniques new to MARIN last year.

The Big Foot TLP, which is designed by FloaTEC and operated by Chevron, represents three important milestones. Firstly, this was MARIN’s 9000th model! Secondly, Big Foot will be the world deepest TLP, at 1,581 m. Big Foot actually required the use of the full depth of the deepwater pit. The third mile-

stone was the individual modelling of all 16 tendons. Thanks to the detailed engineering of this complex model the test programme was completed successfully.

The WISON TLP concept is based on an industry standard, four-column design. The TLP has been engineered to accommo-date a full drilling package, as well as having the ability to process production from both dry and wet trees. A model of the WISON TLP concept was tested in wave, current and wind corresponding to a severe offshore environment prior to undertaking the detailed design of the structure.

The Papa Terra TLWP, designed by FloaTEC, is part of Papa Terra P61 field development and will be accompanied in the field by a semi-submersible for tender assisted drilling and an FPSO for storage. All three floaters were modelled together in the Offshore Ba-sin and linked to each other by means of a hawser and fluid transfer lines. The presence of three floaters in the basin was again, one of the special moments of 2010.

Deepwater pit proves popular for TLP model testsMARIN’s deepwater pit in the Offshore Basin allows

modeling of TLPs, including their tendons, over the full

water depth. Here, we delve the inner depths of the

deepwater pit and examine these challenging projects.

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Papa Terra TLP

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Ormen Lange TLP

1000

67

Wison TLP

Big Foot TLP102994

ue to be installed in 2011, the FSRU Toscana of the Offshore LNG Toscana (OLT) project will be one

of the first offshore LNG floating storage and regasifcation units in the world. The FSRU Toscana is a turret-moored, converted LNG carrier with spherical tanks that will be an-chored in the Mediterranean, 23 km off the coast of Livorno, Italy. LNG will be imported by mooring LNG carriers alongside the FSRU. After contracting ECOS (a joint ven-ture of Exmar Offshore Services and Fratelli Cosulich) as the future operator and Fratelli Neri as the tug company for the facility, OLT commissioned MARIN’s Nautical Centre MSCN to prepare a training programme for the mooring masters, terminal managers and tug masters that will be mooring the LNGC’s there later this year.

MARIN had already carried out several ma-noeuvring simulation projects in the design

stages of the development of Floating LNG (FLNG) but in December last year, MARIN’s Full Mission Bridge simulators were used for the first training courses for the mooring and tug masters. This comprehensive simulation programme included five days of side-to-side berthing and deberthing of an LNGC in bad weather conditions.

After a database for the simulations had been prepared, a two-day workshop was held. During the workshop a few preliminary sim-ulator runs were carried out to get an idea of the required manoeuvres and to evaluate the database. The results were used to fine-tune the simulation scenarios and for further detailing of the training programme. During the simulations each participant in the operation had his own simulator bridge. Communication between the vessels and the simulator supervisor connecting the mooring lines was included in a realistic way.

Participants included:- A mooring master who led the operation

from the bridge of the LNGC on Full Mission Bridge 1, together with an FSRU terminal manager acting as the master of the LNGC and a helmsman following the course or rudder orders.

- A tug master operating the bow tug on Full Mission Bridge 2. This bridge was more suitable because the bow tug is manoeuvring more during the operation.

- A tug master operating the stern tug on the compact simulator.

- And the FSRU terminal manager operating the heading control/stern thruster on a tertiary station and informing the approaching LNGC on the heading of the FSRU.

All of the participating masters were very professional and showed a high level of manoeuvring skills. Their skill level meant

that the training sessions could focus on emergencies and more in-depth operational details which will in turn, serve to develop and optimise the strategies for various events. Only a few simulator runs were used for normal arrivals and departures under the limiting metocean conditions pre-determined by OLT. Based on discussions in the workshop, a range of possible scenarios was created. These ranged from failures of the main engine or rudder of the LNGC, to an emergency departure commanded by one of the tugs assuming the LNGC was out of operation due to a fire.

Undoubtedly, the workshop and training sessions proved to be very useful for all the participants. The workshop was the first time that they had met, so it facilitated a broad exchange of views on certain aspects of the operation. In the workshop, the par-ticipants agreed on the way orders to tug

masters would be given regarding the required direction and force.

The simulations also proved useful for the mooring masters and tug masters in under-standing each other’s position in the operation by observing the manoeuvre on another bridge. In the training simulations the arrival manoeuvres showed no particu-lar difficulties and in fact, they showed that they could even be carried out at higher wind speeds than the present limits from the design stages. Departures in cross- conditions appeared to be more challenging because the FSRU has a tendency to trail behind the departing LNGC. Just before operations start a short rehearsal training will take place. In that session, the Portable Pilot Unit used by the mooring masters will be connected to the simulator so they can familiarise themselves with this equipment.

MARIN’s Full Mission

Bridge simulators

provided simulation

training for what is

believed to be the

world’s first FSRU

installed offshore.

Report outlines the

programme.

Valuable training on LNG Floating Storage and Regasification Unit


D

Johan Dekker

[email protected]

n an ambitious project for the Papa Terra P61 field development, MARIN recently carried out model tests on a

Tension Leg Wellhead Platform (TLWP), a semi-submersible and an FPSO all at the same time to assess interaction effects between the three coupled floaters. The floaters will be operated by Petrobras in a 1,185 m water depth, offshore Brazil.

The TLWP and the connections between the floaters were designed by FloaTEC. For the wave basin model tests the TLWP was moored with eight tendons installed in the deepwater pit of the Offshore Basin. Located at a distance of 35 m from the TLWP, the semi-submersible platform will be used for tender assisted drilling during the first three years of the field development. The semi was installed in the Offshore Basin by means of a truncated bundled mooring system, representing the mooring system

stiffness of the full depth system and it was coupled to the TLWP by means of a hawser system. The complex hawser system was modelled by means of linear springs linked together to represent the non-linear stiff-ness characteristics in surge, sway and yaw correctly. To be moored 350 m away from the TLWP, the FPSO was also modelled in the basin to investigate the interaction ef-fects of radiating waves. Fluid transfer lines run from the TLWP to the FPSO.

Movable floor Due to the complexity of this three-model test setup, a detailed installation plan was prepared prior to the test campaign. All of the installation proce-dures and test configurations were accu-rately verified and documented to minimise any risks during the installation in the Offshore Basin. The movable floor of the basin again proved to be a helpful feature to minimise the installation time of the setup.

Only three yellow bodies can clearly be observed above the still waterline but under water and in close proximity to the basin, a lot of equipment, structures, actua-tors and instrumentation were installed to complete the test setup. In total, more than 80 measurement channels were simultaneously recorded during the three-body basin tests. Video cameras were accurately positioned above and under water to capture the coupled motions of the TLWP and the semi-submersible. These videos, combined with the analysis of the measured relative motions, proved to be a helpful and powerful tool to help understand the hydrodynamics of such a complex coupled system.

VIM tests After the wave basin test programme VIM tests with the coupled TLWP and semi-submersible were per-formed in the Depressurised Towing tank.

These investigated the VIM and galloping interaction effects and the coupled system response. The TLWP was mounted under-neath an air bearing system to model the displacement correctly, without modelling the tendons and without affecting the mass and inertia of the model. The semi-submersible was installed in the basin by means of a horizontal mooring system and coupled to the TLWP with the hawser system.

In addition to the test series described, MARIN also advised on the model test programme for the TLWP alone, which was performed at the LabOceano Offshore Basin in Brazil. A close cooperation between MARIN’s engineers, its local agent Oceanica LabOceano and FloaTEC during the prepa-rations, as well as during the execution of the model test programme, resulted in a very successful model test campaign.


Jorrit-Jan Serraris &

Eelco Frickel

[email protected]

IComplex coupled model tests for Petrobras

Model tests were carried out

simultaneously on three floaters in

MARIN’s Offshore Basin and these

were followed by two-body, coupled

VIM tests in the Depressurised

Towing Tank. The complexities of this

coupled model test programme are

unravelled for the first time.

11051

2

TAD semi submersible (right) coupled to TLWP (left)

110614

3 body model tests in the Offshore Basin: TAD semi submersible, TLWP and FPSO (from left to right)


104652 108012

Arjen Koop &

Jule Scharnke

[email protected]

T he DeepDraft Semi® of SBM Atlantia Inc., the Bigfoot TLP of Chevron and the Papa Terra field

two-body, semi-submersible and TLWP of FloaTec are some of the structures MARIN has tested recently.All the VIM tests were successfully carried out in MARIN’s Depressurised Towing Tank. Measuring 240 m x 18 m x 8 m, this basin has proven extremely suitable for testing due to its long tow length and large cross-

section area. A uniform current flow was simulated by towing the model in calm water. Optimised test programmes were carried out to investigate the VIM response. The tow tests clearly indicate that VIM response is dependent on current heading, velocity, hull design and column draught, shape and its orientation.

For most tests a simple and easy-to-use set-up was created based on previous

projects utilising an air bearing system and vertical mooring springs. The air bearings mean that the models can be tested at the correct mass/displacement ratio, which is important for TLPs. They have an extremely low friction in the horizontal plane and restrict the heave, roll and pitch motions of the structure. This setup ensures a set of ‘clean’ tests, where the total damping and flow patterns originate from the structure’s hull alone. In addition, the tow heading of

the model could be changed very quickly and efficiently in the basin.

Challenging two-body VIM tests The two-body VIM tests - with a TLP coupled to a semi-submersible in close proximity - were particularly challenging. Comparing the results for the TLP alone with the coupled tests sees the VIM response of the TLP change. If the TLP was downstream of the semi-submersible this could relate to current

shielding effects and an unsteady, or dis-turbed inflow to the TLP. However, when the TLP is located upstream the VIM motions change, probably due to the coupling with the hawser and semi-submersible.

These tests again show that VIM is parti-cularly important for fatigue issues and that it remains an important phenomenon that should be taken into account during the design stage.

Increasing interest in tests for Vortex Induced MotionsFor Marin 2010 was a very busy year for Vortex Induced

Motions (VIM) tests. Report highlights the latest tests.

BigFoot TLP Papa Terra field TAD and TLWP DeepDraft Semi® (Courtesy SBM Atlantia Inc.)


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L Larger and more efficient wind tur-bines are being installed offshore due to the higher wind energy

potential. Nowadays, fixed offshore wind turbines are being installed in shallow water. However, technology is improving and the wind turbines are expected to move to deeper water where the wind is more frequent and stronger. The challenges of fixed and floating offshore wind turbines are very similar to those of the offshore industry: safe and economic design, production, transportation, installation, maintenance, repair and removal. Therefore, MARIN is committed to the investigation, design and development of these new fixed and floating offshore wind turbines.

Model tests for floating wind tur-bines In 2011, MARIN’s Renewable Energy Team (RENT) will test three different floating wind turbine concepts for the University of Maine-led DeepCwind project. The floaters include a spar buoy, a tension leg platform and a semi-submersible. The model tests are being conducted to calibrate and validate simulation codes for floating wind turbines. Therefore, great attention will be paid to the coupling between aerodynamic and hydrodynamic behaviour. For example, the modelling and documentation of the wind field in the basin will be given special attention, as well as the relation between turbine behaviour and wind loading on the rotor.

From 2010 to 2014, MARIN will participate in the FP7 project “Future Deep Sea Wind Turbine Technologies” (DeepWind). The hypothesis of this project is that a new floating vertical axis rotor concept, specifi-cally developed for offshore applications, has the potential to offer better cost effi-ciencies than existing offshore technology.

Simulation code for floating wind turbine Designing an Offshore Floating Wind Turbine (OFWT) brings new mechani-cal constraints to the nacelle and the rotor. The motions of the floater affect the perform-

ance of the wind turbine and vice-versa. As wind turbines get taller even small pitch or roll rotations can result in large motions at the location of the nacelle. To properly predict the motions of the floater, rotation of the rotor and the flexible nature of the blades and tower, the structural response of the wind turbine on the floater needs to be taken into account. MARIN and Energy Research Centre of the Netherlands (ECN) are working together to tackle the many challenges of the design of an OFWT. Therefore, the aero-elastic code PHATAS of ECN is being coupled to the multi-body, time-domain simulation code, aNySIM of MARIN. This facilitates a simultaneous calculation of all the aspects of an OFWT in one numerical simulation.

High quality local wind field in MARIN’s Offshore Basin To assist in the testing of floating wind turbines, MARIN is presently working on a high quality, local wind field setup in its Offshore Basin. The wind field is generated by a square bed of 5*5 wind fans with guides and stators (straighteners). By controlling the RPMs of the different rows, the vertical profile of the wind can be controlled. CFD calculations are being carried out to assist in the design

of the final, dedicated wind setup as illus-trated in the figures.

Wifi JIP At the end of 2010 more than 60 representatives of the international offshore wind industry gathered at the Offshore Wind Seminar organised by MARIN and ECN. This seminar provided a unique opportunity to see model tests being carried out at MARIN’s fa-cilities that showed the impact of breaking waves against an offshore wind turbine. This pilot series of model tests was carried out with a special model of an offshore wind turbine with realistic flexibility. The tests confirmed that breaking waves can induce significant oscillations and accelerations in the turbine, resulting in extreme fatigue loads on the foundation, tower, turbine blades, shaft, gearbox and generator. To further study this subject, MARIN and ECN, together with a number of other partners, are in the process of starting up a Joint Industry Project (JIP) with the acronym ‘WiFi’: Wave impacts on Fixed turbines. The objective of this WiFi JIP is to improve the manner in which the effects of steep (and breaking) waves are taken into account in the design meth-odology of fixed offshore wind turbines, so that optimized offshore wind turbines can be developed.

MARIN has the wind in its sails pledging commitment to offshore wind sectorWith the growth in renewable energy, there is an increasing focus on

offshore wind. The offshore wind industry is maturing and going further

offshore into deeper and more challenging waters. MARIN too, is actively

participating in the development of the offshore wind energy sector.

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Breaking wave on a wind turbine scale model with realistic flexibility in the MARIN facilities during the Offshore Wind Seminar

CFD results for existing wind set-up in Offshore Basin

New wind set-up to test

floating offshore wind

turbines in Offshore Basin

Erik-Jan de Ridder, [email protected]

As the offshore industry moves into deeper and deeper waters, there is an increasing focus on riser integrity management in order to ensure that the assets and operations are managed in a cost-effective, reliable and safe manner. Riser Condition Monitoring and inspection, including processing and analyses of the monitored data, form an important part of integrity management, providing valuable information about the accumulated fatigue damage and remaining lifetime of the riser system. However, the actual Riser Condition Monitoring systems do not show why the accumulated fatigue damage deviates from design predictions.

The MonaRisa JIP aims to develop an alter-native method by using the fatigue design tool of the riser system and measurements of the environmental conditions, vessel mo-tions and the riser deformations. As well as showing the lifetime consumption of the riser system, the method will also explain why the actual lifetime consumption deviates from design predictions and it will advise how fatigue consumption can be reduced.

Proven technology The basis of the MonaRisa methodology is a proven techno logy that was developed for FPSO hulls within the Monitas project. This methodology was devel-oped only recently and measures, explains and advises on lifetime consumption of FPSO structures as described by L’Hostis, Kaminski and Aalberts in “Overview of the Monitas JIP”, Offshore Technology Conference, May 3-6 2010, Houston, Texas, USA, OTC-20872. The methodology is schematised in the figure below. For selected marine floating structures equipped with risers, the meth-odology and software will be developed and tested based on two years of measure-ments. Led by MARIN, MonaRisa will be carried out in cooperation with representa-tives from oil companies, vessel operators, designers and authorities. A brainstorm session was held during the JIP FPSO Week in Monaco (March 21-25, 2011).

Managing fatigue in riser systems

Report spotlights the new MonaRisa Joint Industry Project

Following discussions with the industry and the success

of Monitas, a new three-year JIP has launched, designed to

provide the offshore industry with specifications and a

methodology for Advisory Monitoring Systems for risers.

Source: PhD Thesis GauteStorhaug

Mirek Kaminski

[email protected]

Different codes and regulations have been developed over the years to ensure that marine structures are designed, operated and maintained safely. And within these rules, allowances are made for defects that should be monitored but that do not jeopardise safe operations. Fatigue cracks, which are very common in welded marine structures due to the cyclical character of wave loading, are examples of such defects. Although there is a lot of effort being undertaken to avoid cracks, operators are obliged to periodically inspect structures for signs of fatigue.

Cracks, which are too long for a safe opera-tion, clearly have to be repaired but those of an acceptable length have to be followed carefully during successive inspections. But growth rates are uncertain and it is not known when cracks will reach their critical length. Therefore, operators usually either increase the inspection frequency or reduce the crack’s length, which leads to higher operational costs.

Affordable, simple system Interviews with operators revealed that they are seek-ing an affordable and simple monitoring system for guarding the length of cracks that have been detected. Such a system should only warn the operator when, and which crack has reached its allowable length and the overall cost of the system should be competitive with the cost of an additional visual inspection by a surveyor.

A three-year Joint Industry Project, Crack-Guard is being launched, with the first meeting held during the last FPSO Forum & JIP Week in March.The main goal of the project is to specify, develop and test the CrackGuard approach, based on recent achievements in wireless networking and micro/nano technology. The project will start with a review of potential applications. In addition, state-of-the-art crack sensing, wireless communication and networking will be reviewed. Current knowledge on crack propagation rates and directions will also be reviewed in order to provide input for the future shape and size of the CrackGuard sensor. Once the system specification has been developed as a prototype it will be tested under laboratory conditions and then on an FPSO. Participants are welcome to join!

CrackGuardit’s all in the name!A new JIP will help ensure the structural

integrity of marine structures. Report cracks

the case open.


Pieter Aalberts

[email protected]


ne of the most innovative fea-tures of the new OPV is a system designed for the Launch and

Recovery of two manned, or unmanned surface vehicles, which is located at the stern. Based on existing systems that are installed on tuna seiners, the new system will provide fast and safe Launch and Recovery procedures in various weather conditions, at speeds of up to 12 knots. For example, with the new system two marine units should be afloat in approxi-mately five minutes. Additionally, the system is entirely hidden by stern doors that open at the last moment, giving the navy a clear strategic asset.

Vehicles are launched and recovered passively, without the intervention of the pilot of the vehicle. The whole procedure is monitored by an operator onboard the OPV. Launch and Recovery of Unmanned Surface Vehicles (USV) can also be performed entirely automatically.

In 2010, MARIN was asked to carry out an operability analysis of the system based on model tests. Model testing offers a relatively accurate picture of the complex hydrody-namics involved and variations or changes in the design can be assessed easily in a short time frame. Tests were performed in MARIN’s Seakeeping and Manoeuvring Basin with a free-sailing, self-propelled model of the OPV and a passive model of a Rigid Hull Inflatable Boat (RHIB). A detailed model of the Launch and Recovery system was made

active so procedures could be initiated remotely at model scale.

Various combinations of weather factors, wave direction and sailing speeds were investigated in conditions ranging from Sea State 3 to Sea State 5. For each combination a series of launches and recoveries were carried out. At the end of each test the operational feasibility was considered, based on a list of specific criteria.

During the tests attention was paid to the alignment of the RHIB in relation to the OPV and to the contacts between the boat and the ship. Observations were limited to the phase where the RHIB is located in the proximity of the OPV in order to optimise the number of Launch and Recovery opera-tions that could be performed within one basin run. However, repeat runs were per-formed with a RHIB located further aft the OPV as well.

Test results showed that the Launch and Recovery system could operate in a wide range of conditions in Sea State 3. In Sea State 4 and 5, operations are possible but they are restricted depending on the wave direction and sailing speed.

Full-scale trials, to be conducted at the end of 2011, will help to get a complete picture of the capabilities of the Launch and Recov-ery system and they will provide a good means of comparison with the results obtained in the basin.

Courtesy DCNS

Model tests for early assessment of Launch and Recovery operations

LAURA JIP launchesNavy operations are increasingly dominated by systems whereby small craft are ope rating from larger platforms. A three-year, Joint Industry Project named “Launch and Recovery of any small navy crafts”, (known as LAURA), has start-ed to design a standard for ship Launch and Recovery systems for the majority of small navy craft. MARIN will act as the manager of the JIP that will be carried out in two phases in close co-operation with navies, shipyards and suppliers.The system aimed at should be flexible enough to handle a wide variety of small craft (50 kg - 12 tonnes) and it should be operational in moderate sea states (4-5 and possibly up to 6). Preferably, it should be able to be used at low to moderate ship speeds and capable of relatively quick Launch and Recovery operations (< 5 min, with the target to launch every two minutes), only requiring a limited number of crew.All participating companies will be represented in the LAURA JIP Steering Group and presenta-tions, reports and other relevant information will be posted on the project’s confidential website.

For more information or participation please contact Frans Kremer at [email protected].

OBastien Abeil & Yannick Bian, [email protected]

DCNS chose MARIN to conduct an

operability study of the Launch and

Recovery system to be installed on

the new GOWIND type Offshore

Patrol Vessels (OPV) that are

currently under construction.

MARINHaagsteeg 2P.O. Box 286700 AA WageningenThe Netherlands

P +31 317 49 39 11F +31 317 49 32 45E [email protected] www.marin.nl

MARIN USA Inc.4203 Montrose Blvdsuite 460Houston TX 77006USA

P +1 83 25 33 80 36F +1 71 32 67 22 67E [email protected] www.marin.nl

marin report 102

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