Ongoing hydrodynamicreserach projectsNew methods and technologies needed to meet the challenges of adapting to future goals.

Highlights.Issue 65/2018

Page 2 – 5 Page 6 – 7

Page 14 – 16

Hull air lubrication: future and challengesInvolved in numerous projects fordecades to develop and test diffe-rent systems of air lubrication.

Assessing costs: a 25-year perspectiveSSPA has conducted a life cycle cost (LLC) assessment of a new Swedish icebreaker.

The Nobel Prize and its implication for mariners’ health and performanceLast year the Nobel Prize in physiology/medicine was awarded to the discoveries of molecular mechanisms controlling the circadian rhythm. The circadian rhythm, mostly affected by light, controls our alertness and sleepiness during the day.

PAGE8 – 9

Page 10 –11

Spatial planning andship routeing systemsAssisting authorities to preparesustainable and efficient plans toensure high maritime safety.

Strategic research planfor hydrodynamicsContinuing to support our clientsand partners with innovative andsustainable maritime solutions.Page 12 – 13

Page 8 – 9

Mariners’ health and performanceThe circadian rhythm and how it is connected to our performance and health.

2 Highlights 65 / 2018 – Hull air lubrication: future and challenges

This quote is by the Nobel Prize winning physicist Albert Einstein, and has been a great inspiration for generations of scientists and researchers. Although this quote dates back many years, I think it still holds true for how we should turn our thinking and imagination into the driving force for developing the world.

I do not know if Albert Einstein had any specific interest in the maritime world or its research. Since he was born in central Europe, I would guess that he did not have much of an interest in the field. Regardless, his attitude to research has always been the inspiration for our thinking and research at SSPA.

Our ambition with SSPA Highlights is to bring you our latest thinking and research. Even if we have high ambitions, we do not believe that we will change the world in the same way as Albert Einstein did. Nevertheless, we do believe that some of our thoughts and research have the potential to change the world for you in your daily operations.

In one of our articles, about how mariner’s health and performance are affected by the circadian rhythm, our research has been inspired by the 2017 Nobel Prize winner in physiology/medicine. In other articles, our research has been inspired by our own experience and thinking. We also describe what form we believe forthcoming research will take, e.g. in hydrodynamics.

We hope that you will be inspired to start thinking about how to change your world when you read this issue of SSPA Highlights. I can assure you that here at SSPA we are more than willing to help you develop that thinking.

Enjoy your reading!

Stefan EliassonPresident & CEO

Highlights.

The goal of reducing fuel consumption, enforced by international regulations and high fuel costs, is motivating ship designers to investigate revolutionary ideas or re-visit old techniques and apply them using new technologies. Hull line optimisation and propulsion system improvements are common practice for achieving this goal, but what if we can eliminate resistance (at least partially) at its source. Air lubrication reduces the drag force on the wetted surfaces of the hull due to the lower viscosity of air compared to water. Powerboats and navy vessels have been using this technique for decades to increase their cruising speed without much consideration to fuel economy. The shipping industry is now recognising the potential of employing this concept for its cargo ships and in the development of the future generation of green vessels. Unfortunately, there is no universal solution since the choice of the method for air lubrication depends on the vessel specification and operating conditions. SSPA has been involved in numerous projects to develop and test different systems of air lubrication for decades. In this article, we discuss some practical aspects of each method.

Hull air lubrication: future and challenges

“The world as we have created it is a process of our thinking. It cannot be changed without changing our thinking.”

The resistance forces acting on the ship have two sources; the process of water displace-ment that results in creation of the wave system and skin friction caused by a moving surface in viscous fluid (water). To minimise the wave-making resistance, the shape of the hull is optimised according to the operational speed and main characteristics of the hull. It is common practice for designers to use computer simulations and model tests for reducing this type of resistance.

To decrease viscous friction, we need to reduce the area of the wetted surface of the

hull, but since we cannot change the total displacement of the ship, the alternative is to replace water with air over some sections of the hull. The general term for this approach is “hull air lubrication” and is achieved in two ways; by completely removing water from the hull surface using pressurised air or by injecting bubbles into the water near the hull wall and thus decreasing the viscous friction.

Air lubrication systems are divided into three categories: air film, microbubbles and air cavity. SSPA has carried out investigations on all these methods by performing tests, simulations and design consultation.

Air film From an early stage of the air lubrication concept, this method has been the primary choice among designers. In 1882, Gustav de Laval successfully tested the idea of an air cushion, possibly for the first time, by releasing pressurised air through several slots on a boat’s hull. Since the purpose of this method is to insert a thin layer of air between the hull surface and the water, a considerable amount of pressurised air is required to maintain the integrity of the air film over a rather limited area of wetted surface.

The air film system is highly effective in reducing viscous drag where the air layer is intact but the efficiency is reduced at higher cruising speeds if the airflow is low. Some

Air lubrication reduces the drag force on the wetted surfaces of the hull due to the lower viscosity of air compared to water.

Airlubrication

Micro-bubbles

Airfilm

Aircavity

hull designs maintain the integrity of the air layer by inserting guides, grooves and compartments to control the airflow. Adding appendages and chambers to the hull would result in higher drag, therefore air chambers are preferable here instead.

Advantages of this method: • Possibility of retrofitting to existing hulls• Very efficient in reducing drag• Minimum effect on manoeuvring

Disadvantages of this method: • High airflow rate is required to maintain

the air layer• Works best on flat and horizontal

sections of hull• Effective only in short range

Air cavity If we consider using a confined section to control the air film, the design becomes an air cavity (chamber). Depending on the size of chamber and cruising speed, air cavity systems (ACS) are divided into single wave, multi- wave and multi-chamber designs.

SSPA has been involved in different projects using all three design concepts for the air cavity system. For the single wave system in the EU project, BB GREEN, the air supported vessel (ASV) designed by SES Europe AS achieved up to 40% drag reduction at a speed of 30 knots compared to similar hulls.

A similar concept was used in the EFFISES project (Energy efficient safe innovative fast ships and vessels) in which the air chambers were placed inside the hull bottom of two catamarans, sized 40 m and 125 m.

Maintaining the air inside the chamber is a challenge for long hulls with slower speeds as the free surface inside the chamber can form a wave system with several wavelengths inside the chamber. The wavelength directly correlates to the square of the speed =2 π V2/g.

SSPA investigated different designs for the project AirMAX (shipowner STENA) to minimise the resistance of the P-MAX tanker model. The extensive study was performed by designing the optimum hull shape to accommo- date the largest flat bottom for air chambers as well as the geometry of the chambers.

In displacement hulls with high block co-efficients, such as tankers, the flat bottom area is 30 – 40% of the total wetted surface. Since the friction resistance of a hull is proportional to the wetted surface as R=Cf ×1/2 ρ V2 S, using an air cavity has a big impact on drag reduction. On the other hand, because of the deep draft and larger volume of the chambers in a tanker, the cost of pressurised air is higher

Depending on the size of chamber and cruising speed, air cavity systems (ACS) are divided into single wave, multi-wave and multi-chamber designs.

Schematic of a large displacement hull with multi-wave air cavity system.

Air cavity

Air cavity

Air cavity

Air blower

Air blower

High speed planing hull

Semi-displacement hull

Displacement hull

Loaded Water Line

PC

P0 = p g d

d

SSPA investigated different designs for the project P-MAX air to minimise the resistance of the 182 m tanker. Photo: Courtesy of STENA AB. Read more at www.sspa.se

4 Highlights 65 / 2018 – Hull air lubrication: future and challenges

compared to smaller hulls. Therefore, it is important to maintain the air inside the chamber as much as possible. A major focus here was the re-attachment at the end of the chamber to prevent extra force acting on the hull.

Advantages of this method: • Lower airflow rate is required to maintain

the air inside the cavity in calm water• No limit in the length of the cavity

Disadvantages of the method: • No possibility of retrofitting the chambers

on existing hulls• Loses effectiveness in high waves and

rough seas

Microbubbles This method is gaining popularity since it can be used on existing hulls. An example of this system is the Mitsubishi Air Lubrication System (MALS) concept. Small bubbles are injected into the water near the ship’s hull through several nozzles, which reduces the resistance. The exact process in which friction decreases in the mixture of air and water is dependent on many factors such as size of the bubbles and where they are injected. However, it is obvious that we need the bubbles to be as close as possible to the solid surface of the hull. The biggest challenge here is to keep the bubbles inside the so-called boundary layer. Through the EU project SMOOTH (Sustain able

Methods For Optimal Design And Operation Of Ships With Air-Lubricated Hulls), SSPA has tested this concept on flat plates and measured the effect of different parameters on minimising friction.

The bubbles that washed away from the area near the hull-wall lose their effect. Therefore, drag reduction only works in a section close to the air outlet. Several air injectors could be placed separately to continuously reduce the drag along the hull wall. The size of the micro-bubbles is also important since big bubbles cannot move inside the boundary layer and the buoyancy force influences their motion.

Advantages of this method: • Possibility of retrofitting to existing hulls• Minimum effect on manoeuvring

Disadvantages of this method: • Effective only in short range• Bubbles grow and don’t stay in boundary

layer

Commercially viable and a stepping stone to the zero carbon emission vessel?Are there enough benefits from hull air lubri­cation solutions to take them into serious consideration when looking into building new vessels or major conversions? The straight answer is; it depends! For naval vessels and racing power boats the business case is

A major focus was on the re-attachment process at the end of the chamber to prevent extra force acting on the hull.

Through the EU project SMOOTH, SSPA has tested a concept on flat plates and measured the effect of different parameters on minimisingthe friction. Read more at www.smooth-ships.eu

Water re-attachment region

ASV hull designed by Effect Ships International AS (SES Europe AS) and tested in SSPA’s facility. Read more about the BB GREEN project at www.bbgreen.info. Photo: Anders Mikaelsson, SSPA.

Alex ShiriProject Manager and Researcher

Alex received his PhD in Mechanical Engineering from Chalmers University

of Technology in 2010 and was employed at SSPA in 2011. He has worked on various research projects regarding hydrodynamics and CFD modelling, specifically hull air lubrication simulation and hydrokinetic turbine design.

Contact information: E-mail: alex.shiri@sspa.se

Magnus WikanderSenior Naval Architect

Magnus graduated with an MSc in Naval Architecture from Chalmers University of Technology in 2004.

Prior to joining SSPA, he held various positions within commercial ship design consultancy and shipyard business, with focus on energy efficiency, newbuilding and conversions. Magnus experience spreads over a wide range, from Naval applications, Luxury yachts to Research vessel and Merchant ships like LNGC. Magnus joined SSPA in 2013 as Marketing & Sales Manager, Ship Design. Since 2018 he holds the position as Senior Naval Architect.

Contact information: E-mail: magnus.wikander@sspa.se

somewhat different. Merchant shipping has to take many aspects into account before introducing new technologies such as hull air-lubrication. The bottom line is safety, the International Maritime Organization (IMO) demands, class rules and national require-ments. Air­film and microbubble techniques have been tried and tested onboard existing merchant vessels, both in new vessels and in retrofits. Safety has also been handled. Air cavity systems are still untested for full size merchant cargo vessels.

The business case needs to be investigated for all techniques. Even though the resistance benefits could be of interest, the net energy consumption – saving in main engine power – should be greater than the additional energy consumption from the air lubrication system.

There is no universal solution since the choice of the method for air lubrication depends on the vessel specification and

operating conditions.

The goal of reducing fuel consumption, enforced by international regulations and high fuel costs, is motivating ship designers to investigate revolutio-nary ideas or re-visit old techniques and apply them using new technologies. Hull line optimisation and propulsion system improvements are common practice for achieving this goal, but what if we can eliminate resistance (at least partially) at its source.

At the same time the energy saving needs to give a larger cost saving than the capital and operational costs the air lubrication system is adding to the balance sheet.

Traditionally, ideas like hull air-lubrication evolve with high fuel oil prices. Today the oil price is much lower than some years ago, but other interesting factors to add to the equation are lurking around the corner. CO2 emission tax! How will it be implemented? The answer will provide a response to what reducing emissions is actually worth.

The other upcoming piece in this puzzle is electrification. How can the use of stored electrical energy change the above calculation? We know that batteries charged with onshore energy only will be a solution for vessels with shorter routes within the foreseeable future. However, what if capacity was sufficient for powering the fans for the air lubrication system? It is all about the business case calculation. Even the smallest gain is positive. Flettner rotors and solar panels are planned on some new vessels as a way to reduce fossil fuel consumption. A combination of increasingly efficient electrical systems and new carbon emission free ways to capture energy at sea might be a step towards making air lubrication systems commercially viable. Then, if the savings in fuel consumptions are invested in more environmentally friendly solutions, like fuels cells, carbon emission free vessels would be the next evolutionary step.

Hull resistance

Wave-makingSource of resistance

Hull formoptimisation

Decrease in area of wetted surfaces

Fluid densityreduction in hullboundary layer

Improvement method

Friction

If not mentioned, photos and illustrations by SSPA.

6 Highlights 65 / 2018 – Assessing costs for new Swedish icebreakers: a 25-year perspective

The icebreakers and their activities are an essential feature of the Swedish infrastructure, allowing it to function in the winter and enabling the ports to be open all year round. Icebreakers provide merchant ship assistance by monitoring, directing, leading and towing. The Swedish Maritime Administration (SMA)is responsible for the Swedish icebreakingservice and has conducted a prestudy on how the current icebreakers can be replaced. The study, which was submitted to the Swedish Government and the Board of the Swedish Maritime Administration, concludes that the design process of the first new icebreaker should begin shortly and by 2030 the five state­owned icebreakers currently in service will either be replaced or undergo a lifetime extension.

To support SMA’s conclusions in the pre- study, SSPA conducted investigations of different aspects, including:

Assessing costs for new Swedish icebreakers: a 25-year perspectiveRenewing Sweden’s icebreaker fleet is a major infrastructure initiative. The existing icebreakers have been in operation for almost 50 years and the new icebreakers are expected to have a similar lifetime. Operational costs for such a long lifetime have a huge impact on the vessels’ total life cycle costs. Based on a number of investigations of key features for a new icebreaker, SSPA has conducted life cycle cost (LCC) assessment of a new Swedish icebreaker.

• Forecast of future tonnage in the Gulf of Bothnia

• Evaluation of alternative fuels• Alternatives for hybrid solutions• Evaluation of different propulsion concepts• Overall feasibility studies of different

options’ capabilities

To support the decisions in an economic perspective, the life cycle costs of different propulsion concepts were assessed.

LCC for different propulsion conceptsLife cycle cost analyses were conducted for different aspects; one aspect having a signifi-cant impact on the total cost is the propulsion solution. Several feasible solutions for the new icebreaker were investigated. The table

presents the estimated costs over a period of 25 years for two of the investigated pro-pulsion concepts. Since the costs are estimated to reflect the differences between alternatives, the figures below should not be considered to represent actual total costs.

Both concepts are diesel electric. Concept A consists of twin rudder and shaft propellers in the aft and twin shaft propellers in the fore, while concept B uses POD propulsion, two in the fore and two in the aft. Of the investigated concepts, concept B is assumed to yield the highest performance, whereas concept A will have weaker icebreaking and manoeuvring capabilities. Concept B will, however, impose additional costs of about SEK 200 million, corresponding to about 10% of the life cycle cost (LCC). The analysis thereby puts a price on the higher performance, which is crucial as a basis for decision-making in the design evaluation process.

Acquisition costs versus operational and service costsPOD propulsion generally generates signifi-cantly higher acquisition costs as it includes more advanced technology and systems compared to shaft propellers. POD propulsion also generates significantly higher support costs. Concept A requires rudders, a factor which slightly increases fuel consumption and thus means higher operational costs. For 25 years of operation, the fuel savings using POD propulsion are not sufficient to com-pensate for the higher acquisition and service costs related to POD propulsion, and the total life cycle cost is thus higher for POD propul-sion. However, as the difference in operational costs mainly relates to the fuel costs, the expected fuel price will have a major impact on the result.

Predicting future fuel pricesThe fuel price development in a 25 years per-spective is difficult to predict. Predicting the

The Swedish Maritime Administration (SMA) is responsible for the Swedish icebreaking service. Their icebreaker fleet consists of Ale, Atle, Frej, Oden and Ymer. Read more at www.sjofartsverket.se. Photo of the Swedish icebreaker Ymer. Courtesy of SMA.

prices on a 50-year horizon, which is the actual expected time of operation for the icebreakers, would be associated with even greater uncer-tainty that would have made the analysis less valuable. It is also reasonable to believe that the icebreakers’ operation will change within a 50-year period and they will probably have to be upgraded and re-built before that. A 25-year horizon was therefore assumed to be an appropriate time for analysis.

The analysis includes three fuel price scenarios. Probably none of the scenarios will correspond to reality and the figures are wrong. The scenarios do, however, serve as part of a sensitivity analysis, which must always be a central component of an LCC analysis.

Valuable despite high level of uncertaintyAll costs are only estimates and based on available information. The analysis is thus associated with a high level of uncertainty for all sub-costs. Even though the accuracy might be low, the analysis has a high value since the process of performing the analysis can reveal future risks as well as potential costs.

The sensitivity analysis may also facilitate the decision-making process as it may give a price for different risks. The uncertainty is thus not a reason to not conduct the analysis. Clearly, substantial costs will occur during all phases of the lifetime. Disregarding any of those, and not conducting an LCC, will lead to an even higher level of uncertainty as decisions are made based on unstructured guesses.

In the current analysis, not all costs are included. The main purpose of the analysis is to be able to compare alternative solutions. Common structures are omitted as the assumed costs for these may just increase the uncertainty and not add extra value to the analysis. The LCC analysis is just one tool for design decision- making. In this case, it enables monetary valuations of performance; is the higher perfor-mance with concept B worth additional costs of about 10%?

Strategies for low LCC for the entire processFor the yard building the vessel, the focus is generally on keeping the building and construc-tion cost as low as possible. For the shipowner

Nelly ForsmanProject Manager

Nelly has an MSc in Sustainable Energy Systems, majoring in Mechanical Engineering.

She graduated from Chalmers University of Technology in 2012. Since joining SSPA in 2014, Nelly has mainly worked on studies of alternative fuels for shipping, LNG bunkering, AIS analysis and maritime risk analysis. Nelly is also currently involved in research projects on winter navigation and ice-related projects. Prior to joining SSPA, Nelly also gained experience of numerous different permit processes.

Contact information E-mail: nelly.forsman@sspa.se

Mikael RazolaProject Manager

Mikael received his PhD in the field of Study Maritime and Vehicle Engineering. He graduated from the

Royal Institute of Technology (KTH) in Stockholm in 2016 and was employed at SSPA in 2017. He has mainly worked with optimising future ships and boats in several perspectives e.g. hull weight, cost, perfor-mance, environment and autonomy (unmanned ships).

Contact information E-mail: mikael.razola@sspa.se

Concept A consists of twin rudder and shaft propellers in the aft and twin shaft propellers in the fore, while concept B uses POD propulsion (integrated electric motor/propeller unit mounted on the same shaft), two in the fore and two in the aft.

and operator, SMA in this case, the life cycle cost is of the utmost importance. To get the best result, the LCC aspects have to permeate the entire process of design, construction and building new icebreakers. With several parties involved in the process, including design com- pany and yard, finding ways to get all parties to focus on LCC instead of low investment costs is essential.

The figures presented are a simplified ex-ample produced from several comprehensive investigations. The LCC conducted for project IB 2020 (Icebreaker 2020) involves a number of aspects and the outcome is used for compa-risons of different design parameters, of which propulsion is one. The results of the LCC analysis are just one tool for decision-making in this matter.

A B

Life cycle costs over a 25-year period for alternative propulsion concept, figures are normalised where Support Cost concept A is set to 1.

Concept A Concept B 4 shaft propellers and 2 rudders 4 POD

Acquisition Cost 9.3 13.2

Support Cost 1.0 3.0

Operational Cost low 19 18

Operational Cost medium 28 27

Operational Cost high 42 40

Life Cycle Cost low 29 34

Life Cycle Cost medium 38 43

Life Cycle Cost high 53 57

All illustrations by SSPA.

8 Highlights 65 / 2018 – The Nobel Prize and its implication for mariners’ health and performance

Life at seaBeing a mariner is a dangerous profession with high risks of experiencing both accidents and health issues. Not enough good sleep certainly increases the risk of personal injuries or even the vessel running aground or colliding with other vessels. Poor recovery is also affected by working shift hours, which is common on board. Chronic sleep disorder is associated with cardiovascular disease, diabetes, depression and other health issues.

The circadian rhythmOur daily rhythm, the so-called circadian rhythm, controls many of our important body functions such as temperature, hormone secretion, metabolism and not least alertness and sleep.

One of the most important external factors, so-called zeitgeber (German for timer), that

In 2017, the Nobel Prize in physiology/medicine was awarded to the discoveries of molecular mechanisms controlling the circadian rhythm. The circadian rhythm, mostly affected by light, controls our alertness and sleepiness during the day. We can all benefit from knowing how to use light to maximise our performance, but it is even more important for mariners who are working and living 24 hours a day in a harsh environment where good recovery is important for safe operation and health. Among all the factors on board that affect sleep and alertness, the impact of light may be less known. SSPA performed an overview, funded by the Swedish Mercantile Marine Foundation, about the effects of light and with a greater insight; mariners can adapt new routines to affect their well-being.

The Nobel Prize and its implication for mariners’ health and performance

controls the circadian rhythm is light. But there are also other zeitgebers such as tempe-rature changes, food intake and social stimuli.It is only recently that we have found out the mechanism of how light affects human circadian rhythm. For 150 years, however, we have had a predominant model of eye function with cones and rods that form recep-tors for light and the formation of vision. It was not until the late 1990s that a new type of light receptors was discovered, special ganglion cells (pRGCs) that are sensitive to the blue part of the light spectrum wave-length at λmax ~ 480 nm.

MelatoninOne of the more interesting hormones directly associated with sleep is melatonin, which is secreted while we are asleep. The secretion is governed by the circadian rhythm controlled

in a part of the brain called the suprachiasmatic nucleus (SCN) located in the hypothalamus about three centimetres behind the eyes. The most potent external influence on the SCN comes from light through the ganglion cells in the eye.

DaylightThe most obvious and natural way to have a good circadian rhythm with a good night’s sleep is to work outside during the daytime. Even short periods outside at lunchtime are beneficial. Note that we should never look into the sun.

There are also other benefits of exposure to sunlight. A recently published study on the overall mortality rate for those who spend a lot of time in the sun showed that their life expectancy is 0.6 – 2.1 years longer than those who avoid sunlight.

“Overview of biological circadian clock in humans” by Yassine Mrabet.

Lars MarkströmProject Manager

He graduated from Chalmers University of Technology with an MSc in Mechanical Engineering

and later gained a BSc in Nautical Science. He has more than 15 years’ experience of industry R&D in the private sector. He joined SSPA in 2012 and manages research projects from multiple disciplines within maritime innovation.

Contact informationE-mail: lars.markstrom@sspa.se

spectrum but also by the brightness. To affect the circadian rhythm, true daylight or at least 1,000 lux of artificial light is needed. Electrical lighting in homes, offices, schools, factories, etc., rarely exceeds 1,000 lux, and is unfor-tunately often significantly lower. Outdoors, the brightness from sunrise is already between 2,000 and 10,000 lux, even on a cloudy day.

Blue light at the right timeIn previous sections, it was described how important light, and specifically blue light, is for the circadian rhythm, provided that it is exposed to the light at the right time, i.e. usually during daytime. But the reverse also applies.

Melatonin, the hormone that is important for sleep and the circadian rhythm, can be suppressed by only small amounts of light, especially blue light. At levels as low as 8 lux, something easily exceeded by a stan-dard table lamp, has an impact.

Some tips for reducing blue light exposure:• If possible, use a dimmed red light in

the evening.

• Avoid watching electronic screens 2 – 3 hours before bedtime.

• Use glasses that block blue light if you still want to watch screens before bedtime.

• There are also apps available that reduce the blue light content from PCs and other devices.

Blue light blockingOne way to reduce unwanted exposure may be wearing glasses that block blue light. Regular cheap sunglasses with yellow or orange lenses block blue light, but have the unwanted effect that colour rendition is also reduced, which does not suit all work tasks. There are special glasses that block only blue light, but these are significantly more expensive and may not be as effective.

There are also apps for PCs and smartphones that will reduce the blue light from the screen. Although much is written about these in news-papers and blogs etc., specific research in the field seems to be almost non­existent so far.

Light management onboard merchant vesselsIf you work outdoors, it will be a part of the usual daily rhythm to get light and darkness at the right time. This will be much more complex when work and rest patterns do not follow the normal daily rhythm, such as several jobs onboard ships.

The United States Coast Guard (USCG) Research and Development Center has prepared a guide on how to improve crew capacity and safety on board merchant ships. The guide is called “Crew Endurance Management Practices: A Guide for Maritime Operations” and is available for download from the USCG website. It describes techniques for adjusting your rhythm for working at night and different shifts, as well as advice on combining this with good night vision.

Blue wavelength in artificial lightingHowever, many tasks onboard are performed inside the ship and the mariners do not get enough exposure to natural daylight. This can be counteracted with illumination which includes the vital blue wavelength. In order to compare light sources with each other, a relative ratio have been employed where a standard fluorescent lamp with a colour temperature of 3000 K, warm white, has a value of 1 and a higher value gives more blue circadian light.

Full-spectrum light sourcesThere are also specialised full spectrum light sources. Among the terms used by manufac-turers, we find full spectrum or daylight type, but this does not guarantee that the proportion of blue light is satisfactory, as there seems to be no uniformly agreed definition for this. These names are more likely to be regarded as marke ting terms. In order to determine whether a light source emits a useful propor-tion of blue light, it is necessary to examine the manufacturer’s specifications. It should also be noted that efficiency may often be lower in full spectrum lamps, i.e. the number of lumens per watt is lower and that this may need to be compensated for to achieve sufficient light in-tensity for a possible light source replacement.

BrightnessThe amount of circadian light exposure is determined not only by the ratio in the light

The demanding 24-hour operation of vessels. Photo courtesy of Lars Markström.

Illustration by SSPA.

1.25 1.00 1.85 2.56 2.91 2.78

Incandescent Fluorescent 3000 K Fluorescent 4100 K Fluorescent 7500 K White LED Daylight 6500K

Examples of our most common light sources:

10 Highlights 65 / 2018 – Maritime spatial planning and ship routeing systems

Sweden implements the Maritime Spatial Planning DirectiveEuropean Union Directive 2014/89/EU re-quires all coastal member states to present an integrated plan by 2021 on how to prioritise the use of sea areas within their economic zone and territorial waters, e.g. how to locate an offshore wind farm in areas with intense sea traffic. In Sweden, it is the Swedish Agency for Marine and Water Management (SwAM) that is responsible for the planning process and the Agency is also coordinating the planning process with neighbouring states. SSPA has been engaged by SwAM to conduct consequence analyses of the possible relo-cation of maritime sea traffic lanes in order to improve the protection of particularly environ-mentally sensitive areas.

Consequences of potential rerouting of ship traffic south of GotlandThe area south and southwest of the Swedish island of Gotland includes the Midsjöbankarna and Hoburgs bank, which constitute the most important wintering habitat for European long-tailed duck and it is also one of very few areas used for reproduction by harbour porpoise (the smallest species of toothed whales). The bird population is severely decimated every winter when thousands of oiled long-tailed ducks are stranded on the shores of Gotland and porpoise reproduction is believed to be disturbed by ship noise from vessels traversing the bank areas. Although no oil spills are observed by air surveillance in the bank areas, researchers assume that the oiling of the diving sea birds must be caused by invisible operational oil discharges from ships passing the main transit lane south of Gotland. SSPA’s consequence analysis shows that the probability of any such potential

The high and rapidly increasing demand for maritime space for different purposes, as well as the multiple pressures on coastal resources, requires an integrated planning and management approach. Rerouteing of shipping lanes and the introduction of new routing systems may be needed to ensure high maritime safety and sustainable co-existence of various marine activities. SSPA’s toolbox and experience assist planning and maritime authorities to prepare sustainable and efficient plans.

Björn ForsmanProject Manager

Björn has an MSc in Mechanical Engine-ering and joined SSPA in 1980. He has

been active in areas related to the marine environment, oil spill prevention and clean-up as well as the reduction of ship emissions and alternative fuels. Maritime safety and risk analysis are currently the main fields of expertise in his projects and in the research projects that he is engaged in. He has also been the programme mana- ger for a number of advanced international training programmes.

Contact information E-mail: bjorn.forsman@sspa.se

The figure shows todays´ AIS traffic pattern, with the main flow north of the banks and the deep draught ship flow south of the banks. The protected banks with their “Areas to be avoided” have recently been included in one common enlarged Natura 2000 area, as indicated in the map.

“SSPA provided qualified input on rerouting consequences in terms of fuel consumption, emissions and safety risks.” – Dr Jonas Pålsson, SwAM.

TSS NorthHoburgsbank

TSS SouthHoburgsbank

Gotland

S Midsjö-banken

Öland

TSS Midsjö- bankarna

Natura 2000 Hoburgs bank and Midsjöbankarna

Area to be avoided

Northbound ship tracks

Southbound ship tracks

Natura 2000 area

Particulary sensitive banks

TSS; Traffic Separation Scheme

DW; Deep-Water route

Area to be avoided

DW 25 m

DW 25 m

operational oil discharges reaching the bank areas would be significantly reduced if the current main transit route through the

N Midsjöbanken

Hoburgs bank

Maritime spatial planning and ship routeing systems

Baltic Sea were redirected to the designated Deep-Water (DW) route located south of the Hoburgs bank.

Deep-Water routeKattegat north

Deep-Water routeKattegat south

TSSLillaMiddelgrund

TSSFladen

TSS Entranceto the Sound

ITZITZ

ITZTSS Skageneast

PrecautionaryareaTSS Skagen

west

Precautionary areaat Kummel bank

Kattegat

Denmark

Skagerrak

Sweden

Great BeltThe Sound

Increased route distance may be balanced by reduced shallow water resistanceSSPA’s consequence analyses also predicted and compared the total fuel consumption and exhaust emissions from the route currently in use and two optional alternatives for rerouting of the traffic. Though the options west of Gotland and south of the Hoburgs bank are longer, it was found that fuel consumption would not increase in proportion to the lengthening of the distance. This was because the shallow water induced additional resistance, was reduced for many ships when they choose the designated Deep-Water route (DW) 25 m, instead. Modelling of shallow water effects in the resistance and fuel prediction algorithms is based on empirical model and full-scale test results gained in SSPA’s joint industry project SWABE, and demonstrates that it is important to carefully model and take into account the shallow water effects when assessing and comparing possible options for new and modi- fied routeing systems. The mathematical models used to calculate added resistance caused by shallow water are also being further refined by being combined with Computational Fluid Dynamics (CFD) calculations, in order to allow estimation of ship-generated bottom erosion effects.

New routing system in the Kattegat and SkagerrakSSPA has conducted comparative consequence analyses for the Swedish Transport Agency and for the Swedish National Road and Transport Research Institute; one study specifically addressed a proposed new routing system for the Kattegat and Skagerrak between Sweden and Denmark. The proposal was jointly sub-mitted by the Swedish Transport Agency and Danish Maritime Authority to the International Maritime Organization (IMO), NCSR 5th session (19 – 23 February). The proposal includes a number of new Traffic Separation Schemes (TSS), a new Deep-Water route, and a separate route for ships in transit to the Sound. Separating traffic to the Sound from traffic to the Great Belt into different routes and sepa-ration of north­ and southbound traffic by TSS will contribute to improved navigational safety. As a result of the proposed changes to the transit traffic in Route T, the total fuel consumption will increase by 3%, between the Skaw and the Great Belt. Considering the total transit traffic through Kattegat, including both the Great Belt and the Sound directions, the calculated fuel consumption and associated emissions are

estimated to be about 0.9% lower than today provided that transit speed is kept unchanged. The calculated total saving percentage is small but converted into monetary terms it corres-ponds to a SEK 4.5 million reduction in fuel costs. The external costs related to greenhouse gases and air pollution together represent a reduction of SEK 7.4 million per year.

IWRAP – tool for maritime risk assessmentThe IWRAP software from Gatehouse Maritime was used by the Danish Maritime Authority (DMA) for design and validation of the new proposed routeing system in Kattegat. SSPA also regularly uses the IWRAP Mk2 version 5.3.0 as a tool for estimating collision and grounding probability in various waterways. The use of IWRAP is recommended by IALA (a non­profit, international technical associa-tion for marine aids to navigation authorities and other stakeholders), and SSPA provides

Proposed new roueting system between Sweden and Denmark to be implemented by July 2020.

All illustrations by SSPA.

IWRAP calculation services e.g. to SwAM for comparative analyses of different rerouting options in the marine spatial planning process and for offshore wind farm localisation studies.

Development of maritime safety and marine spatial planning requires expert cooperationIt is well known that development towards more sustainable cargo transportation systems includes modal shift from road to seaborne solutions. The predicted future increase in sea traffic and the ongoing process of preparing marine spatial plans highlight the need for creative cooperation efforts between quali-fied mariners, naval architects, risk analysts, environmentalists and planning experts. SSPA has the expertise, experience and tools – let us be your maritime solution partner.

Legend Existing T-route Modified T-route New S-routeTSS Traffic Separation SchemeITZ Inshore Traffic Zone

12 Highlights 65 / 2018 – Strategic research plan for hydrodynamics

Two-way knowledge flow At SSPA, all specialist engineers can be involved in research and development (R&D) in addition to the commercial work. This facilitates a two­way knowledge flow between research and business. It also makes the job as a specialist at SSPA stimulating and evolving. The decentralised R&D­organisation does, however, require very clear management with defined goals, roadmaps and prioritisation. Otherwise, it is tempting to solve the problems that are right in front of you, without consi de-ring the full picture.

Accurate and independent evaluation The starting point of the strategic research plan is also the endpoint: “What is our role in the society of the future?” We believe that our fundamental mission will remain unchanged: to act for sustainable maritime development by providing hydrodynamic advice and expertise. Our main contribution in the hydro- dynamic field has always been, and will continue to be, to assist the maritime industry with performance assessments at the design stage. Our recommendations are always based

What will be tomorrow’s challenges in the shipping world, and how can SSPA contribute to the solutions? What kind of services will be requested? What tools do we need to develop to meet these demands? Knowledge-based organisations like SSPA constantly have to adapt to a changing world. Our strategic research plans help us to set the direction and to break down the challenges into manageable goals. Structured research and development is a prerequisite for continuing to support our clients and partners with leading edge, innovative and sustainable maritime solutions.

Strategic research plan for hydrodynamics

on scientific knowledge that is systematically tested and verified. Without accurate and independent evaluation, the ship building industry cannot develop energy­efficient and safe vessels.

A range of tools for different situationsThe next step in forming the research plan is to forecast which questions society will pose, and try to identify the possible tool that can be used to answer these questions. A potential pitfall is focusing only on the newest and most advanced technologies. However, the toolbox should contain a range of tools for different situations. We need to deliver solutions with a confidence level that is high enough, and at a cost that is in line with that level. Take for example the question: “What will the power demand be for this ship?” In the beginning of the design stage, a rough estimation is pro-bably enough. As the design work continues, a comparative assessment against a similar ship is requested, and later in the process an absolute prediction to the highest possible confidence level is required for the builders’ contract or Energy Efficiency Design Index

(EEDI) certificate. Obviously, different tools are utilised to provide the predictions in each situation.

Identify the gapsBy mapping the anticipated future services and tools, it is possible to identify the gaps where R&D is needed. A gap in the matrix obviously means there is a tool that we need to develop. But it can also mean a tool that we do have, but which is not accurate enough or is too expensive to use.

With the tools map and the identified gaps to hand, the last step in devising the Research Plan is to break down the work into manage-able packages, set priorities and draw up the detailed timetable. The work is organised into a number of programmes, and we can present the plan for three of them here.

Energy efficiency in calm waterThe services related to this area include e.g. design optimisation of hulls, propellers and appendages, as well as prediction of the attained speed for an EEDI certificate or builders’ contracts. Traditionally, these services have been based on towing tank

Analysing the energy efficiency of the hull on RS 158 Idar Ulstein using EFD, (Experimental Fluid Dynamics) and CFD (Computational Fluid Dynamics).

test, Experimental Fluid Dynamics (EFD).There is no doubt that Computational Fluid Dynamics (CFD) will take on an increasing role not only for design optimisation but also for predictions. In fact, it already has. Switching to pure CFD-based methods for high confidence speed­power prediction and comparison of complex cases is still not a reliable option. We believe, however, that there is great potential in using CFD and model testing in combination.

Most of our R&D activities in this programme are aimed at improving today’s methods by developing different types of CFD/EFD hybrid methods (combined methods). Some examples worth mentioning are form factor determination, effective wake scaling, propeller open water curve scaling, submerged transom scaling, skin friction scaling of rough and fouled surfaces, skin friction scaling of appendages and scaling of energy saving devices.

New methods finally need to be internatio-nally accepted and formalised as standards. For that reason, and as part of SSPA’s strategic research programme, we are currently chairing the newly started Specialist Committee on Combined CFD/EFD Methods under the International Towing Tank Conference (ITTC).

Seakeeping and energy efficiency in wavesUp until now, the seakeeping assessments at the design stage have most often focused on safety and manoeuvrability, but gradually more attention is being given to the effect of waves on fuel consumption. The introduction of the weather factor fw in the EEDI rule (Highlights issue 64/2017) has paved the way for this development. There is a risk, though, that optimisation towards lower energy consumption (i.e. a better EEDI) will lead to ships that are dangerously underpowered. This risk will be addressed by the International Maritime Organization (IMO) regulations limiting the minimum installed engine power,

Sofia WernerManager Strategic Research – Hydrodynamics

Received an MSc in Naval Architecture from Technical University of Denmark

(DTU) in 2001 and a PhD in Naval Architecture from Chalmers University of Technology in 2006. She joined SSPA in 2007 and worked with ship design, CFD and towing tank testing for commercial clients for eight years. Since 2016, Sofia has managed the strategic research plans in the area of hydrodynamics. She is currently chair of the ITTC Specialist Committee on Combined CFD/EFD Methods.

Contact information E-mail: sofia.werner@sspa.se

Measuring the propeller efficiency and cavitation erosion, examples of evaluation using EFD and CFD.

which will call for the assessment of a ship’s manoeuvrability in severe weather at the design stage. That is a very challenging task to simulate in model tests, and even more demanding with numerical tools.

A consequence of the new trends is that we will need to deliver seakeeping assessments that are more accurate and precise than before, and of different types than what we are used to, e.g. more regular waves and lower speeds. Our R&D projects in this programme aim to meet this demand by improving test technique and smart processing of measured data so that we can maintain the competitive costs and delivery times. At the same time, we are also working on new strategies for using seakeeping CFD methods in the design process as well as assisting with procedures based on the model test.

Propeller cavitation and erosion The ambition to achieve higher energy effici­ency leads to propeller designs with small safety margins in relation to cavitation and erosion. On top of that, there is increasing awareness of the harmful effect of ship- generated noise on sea life. We therefore believe that the demand for accurate predic-tions of propeller cavitation at the design stage will continue to grow. Our R&D in this area includes e.g. the development of a new testing technique using acoustic emissions. Moreover, research is being carried out on CFD-based prediction methods for erosion and noise emission, even though there is still a long way to go before commercial applica-tions are likely to be a reality.

Worldwide allies Interaction with the global maritime com- mu nity is a key part of our strategic research programmes. The aforementioned work in the ITTC Specialist Committee on Combined CFD/EFD Methods is one example. Another is our membership of the ITTC Seakeeping

A question with consequencesThe efficiency is 3% higher for one of these propellers. 10 sister vessels are built and each one sails for 25 years. That makes a 500,000 tonne CO2 diffe-rence if the right propeller is selected.

Do you dare to take the decision without an independent evaluation?

Committee, which among other things deals with the recommended procedures for deter-mining the EEDI weather factor fw. The “Community of Practice on Noise” under Hydro Testing Forum is yet another important research ally. Through these channels, we can receive valuable input and ideas, as well as contributing directly to the development of new global standards and methods. And that takes us back to where we started: our mission to act for sustainable maritime development.All photos and illustrations by SSPA.

14 Highlights 65 / 2018 – Ongoing hydrodynamic research project

To remain a world-leading company at the forefront of hydrodynamics and deliver innovative and sustainable maritime solutions for our clients and partners we need to continuously sharpen our tools. New methods and technologies will be needed to meet the huge challenges of adapting the shipping industry to future economical as well as environmental goals. At SSPA, our specialists are involved in research and development in parallel with their commercial commit-ments. In this way, there is a direct link between R&D and commercial application. Four of our hydrodynamic experts will here present examples of ongoing hydrodynamic research projects intended to improve today’s methods in different areas.

Ongoing hydrodynamic research project

Research on predicting the risk of cavitation erosion on ship propellers

Jan HallanderProject Manager

Jan graduated with an MSc in Mechanical Engineering in 1991 and received his PhD in

Naval Architecture from Chalmers University of Technology in 2002. He has been at SSPA since 1998. He has been involved in various research and consultancy projects in the areas of general hydromechanics, propulsion and underwater acoustic signatures, with a particular focus on phenomena related to cavitation and noise induced by propellers.

Contact information E-mail: jan.hallander@sspa.se

Has this propeller risk of cavitation erosion damage? Ongoing tests on a propeller in our Cavitation tunnel. Photo: Anders Mikaelsson, SSPA.

Damage to propellers due to cavitation erosion is a phenomenon that is becoming more frequent as propeller designers try to increase propeller efficiency. Energy­efficient propel-lers have usually some amount of cavitation at the design point and cavitation erosion damage may then occur, especially if the ship is operated off-design. An alternative design with a lower cavitation volume is not generally

acoustic method that will allow model-scale tests to predict and quantify the risk of erosion at full scale, which will include the develop-ment and testing of measuring equipment to determine whether the acoustic emission tech-nique is useful in a model scale and the extent to which the method correlates with full-scale observations. This new method will enable the fast and reliable scanning of a large number of operating conditions in order to map them, figure out which operational range is safe and what the risk of cavitation erosion is. The project will run until April 2019 with the part-ners Lloyds Register, Daewoo Shipbuilding and Marine Engineering, and the University of Southampton.

“ Need to find new measurement methods to

optimise propellers while at the same time minimising the

risk of cavitation erosion.”

acceptable since this usually increases the fuel consumption. Our experts understand that there is a growing need to find new measure-ment methods to optimise propellers while at the same time minimising the risk of cavita-tion erosion. The measurement methods used today are too time-consuming to be used in more than a few operating conditions.

SSPA is collaborating on a project with other partners who are world leaders in their fields. The project will primarily develop an

Improved standards for ship performance evaluation in the design stage are a prerequi-site for reducing the energy consumption of the world’s fleet. The existing official standards are based on experimental methods (EFD). Numerical methods (CFD) have been introduced as alternatives, but they cannot be used stand­alone with high confidence. Could hybrid CFD/EFD methods be the way forward? Our researchers are now trying to answer questions such as: how can EFD and CFD be combined in smart ways, what is required to correlate and validate the methods before they are adopted as standards, how can the quality of the new methods be assured and how are these standardised?

SSPA and Chalmers University of Techno-logy run a joint research project on power prediction methods using combined CFD and EFD since January 2018. By developing new hybrid methods, we take advantage of the benefits of both approaches and ensure higher confidence in the predictions. The project will run until the end of 2020 and will primarily develop a strategy for developing hybrid methods. The work includes mapping the need for improvements and evaluating different approaches, CFD/EFD combined methods and strategies to ensure the reliability of new methods. The project is linked to the Specialist Committee on Combined CFD and EFD Methods of the International Towing Tank Conference (ITTC).

Research onimproved prediction methods for ships

Research on predicting ship performance in waves

Traditionally, contracts between shipyards and shipowners are based on the fulfilment of a single contractual point, namely that a ship achieves a certain speed with a given engine power in calm water. Such a one-sided approach can obviously result in the ship per-forming poorly in off-design conditions. It is for this reason that the current focus seems to have moved away from that single contractual point and towards operational profiles, design for overall performance and the ability of a ship to fulfil a certain transport task in a given time. This paradigm shift is closely related to today’s emphasis on energy­efficient ship-ping, slow steaming and route optimisation. Modern ships are now designed to perform well in a range of realistic conditions rather than merely in calm water. Consequently, performance predictions under the influence of wave and wind loads are becoming more and more important. This in combination with the introduction of the Energy Efficiency Design Index (EEDI) has resulted in nume-rous ideas such as improved bow shapes to reduce “added resistance” in waves. The International Maritime Organization (IMO) has also introduced guidelines to determine the minimum propulsion power that can be used to maintain the manoeuvrability of ships in adverse conditions.

Our experts find that manoeuvring and seakeeping performance generally features too late in the design process and that sometimes

Sofia WernerManager Strategic Research – Hydrodynamics

Received an MSc in Naval Architecture from Technical University of

Denmark (DTU) in 2001 and a PhD in Naval Architecture from Chalmers University of Technology in 2006. She joined SSPA in 2007 and worked with ship design, CFD and towing tank testing for commercial clients for eight years. Since 2016, Sofia has managed the strategic research plans in the area of hydrodynamics. She is currently chair of the ITTC Specialist Committee on Combined CFD/EFD Methods.

Contact information E-mail: sofia.werner@sspa.se

Frederik GerhardtSenior Technical Expert

Frederik received a Dipl.-Ing. in Aeronautical Engineering from RWTH Aachen in Germany in

2005 and a PhD in Mechanical Engineering from the University of Auckland in 2011. He has been employed at SSPA since 2011 and has mostly worked on research and consultancy projects related to seakeeping and manoeuvring issues. Frederik has been a member of the International Towing Tank Conference (ITTC) Seakeeping Committee since 2014.

Contact information E-mail: frederik.gerhardt@sspa.se

Ongoing research to increase knowledge of a ship’s added resistance in waves. SSPA is now conducting a research project to increase the accuracy and efficiency of detecting added resistance in waves experimentally and numerically. Photo: Anders Mikaelsson, SSPA.

the shipyards have to make costly and time- consuming last-minute changes to the design if the standards for ship manoeuvrability are not met or seakeeping performance is poor. All these developments increase the demand for ship manoeuvring and seakeeping perfor-mance with higher accuracy than before, and stipulate new and more stringent requirements for testing techniques and evaluation methods. SSPA is now conducting a research project to increase the accuracy and efficiency of detec-ting added resistance in waves experimentally and numerically. More accurate and efficient numerical and experimental procedures will make it possible to cost-effectively predict over-all ship performance in a seaway early during the design process and to avoid costly pitfalls.

16 Highlights 65 / 2018 – Ongoing hydrodynamic research project

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Merchant vessels are getting bigger and bigger, but what if their weight and the amount of steel required to build them could be reduced? It may be possible to optimise the design to reduce the weight and quantity of steel and thereby lower the cost of building and operating the ship. This will make transports more energy efficient and reduce the environmental impact on the sea, and might also lead to reduced costs for the shipowners when building the ship. More research is needed to ensure that lighter hulls satisfy requirements in terms of strength, sea characteristics, environmental requirements and maritime safety. According to a pre-study conducted in 2016, dimensional regulations do not fully take into account the interaction between wave loads and the ship’s dynamic response. There is uncertainty as to whether the safety margins are sufficient or unnecessarily conservative, which may lead to vessels being oversized and having a higher energy consump-tion and environmental impact.

SSPA together with Chalmers University of Technology, the Royal Institute of Technology (KTH) and Stena Teknik has been conducting joint research on methods of dynamic ship

Research on dynamic design of ships

Jonny NisbetProject Manager

Jonny received his MSc in Naval Architecture from the Chalmers University of Technology

in 1989 and his PhD in Thermo-Fluid Dynamics from Chalmers in 1994. He has worked for SSPA since 2009, except for one year spent on research and consultancy projects related to manoeuvring and seakeeping. He specialises in submarine hydrodynamics, model testing and the simulation of manoeuvring performance.

Contact information E-mail: jonny.nisbet@sspa.se

dimensioning and the understanding of dynamic loads on ships since March 2017. During this project, a vessel model has been manufactured that is equipped to measure structural loads. Model wave tests will also be performed, and numerical calculations will be validated against the model wave tests. Stena’s concept vessel Stena Elektra has been chosen as a model vessel. The project will be completed at the end of 2018.

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