sspa highligts 57/2013 · sspa was contracted by the port of rotterdam to improve the...

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Marine transport in the Stockholm Bypass projectRisk analysis, evaluations and costings.

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Port of Rotterdam maneuvers in SSPA´s simulator labOptimize to improve accessibility.

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Highlights.Issue 57/2013

Make A Difference on LNGA collaboration project with Sirius Shipping, Viking Line, DNV, FKAB, PREEM and the Swedish Shipowners’ Association.

SEAMAN simulations improve fairway, port planning and designAn upgrade of our in-house tools.

Large Area Propeller (LAP)SSPA is one of 21 partners in the STREAMLINE project.

E-Fleet A strategic decision support tool for energy-efficient fleet design.

Prediction of under-water radiated noiseTesting tools in a benchmark study.

Designing a new port, or modifying an existing one, are complicated processes involving many stakeholders and even more fields of expertise. Using the expertise of mariners, infrastructural planners, logistics experts, environmental experts and a few dozen more fields of expertise these projects are truly a multi-disciplinary endeavor. SSPA’s staff of mariners, risk analysts, plus maneuvering and port management experts have, for more than 40 years, been involved in many port infrastructure projects, in order to provide customers with efficient and safe operational solutions. At present SSPA has upgraded its in-house simulation tools, with specific focus on adequate mathematical modeling and virtual reality, all in order to meet customers’ needs for optimized solutions, flexibility and rapid response.

To understand customers’ needs and problems, SSPA invites them to an open and professional dialogue. This is where the best use of SEAMAN simulations can help resolve key issues. Since SEAMAN is designed for this, it can handle a number of customer concerns: bank and shallow water effects, stratified and time variable currents, wind and wave effects, etc. SEAMAN is designed as a tool to help solve our custo-mers’ concerns and our simulation experts are very well versed in its capabilities. It is also important to understand and see the broader picture, to understand its purpose in order to provide clients with results and recommendations.

SEAMAN simulations improve fairway, port planning and design

Knowledge as a toolAs a company SSPA is growing, both in size and in adding new knowledge. The main focus areas in which we work include:• acting as a bridge between research and implementation in the maritime industry• optimizing for energy efficiency while keeping environmental, financial, human and technology factors in mind and• ensuring sustainable development through proper risk management.Our vision is unchanged as we strive to be recognized as your most rewarding partner for innovative and sustainable maritime develop-ment. To be able to reach this vision we have defined four core values that we as a compa-ny believe in and live by. One of them is to use our knowledge as a tool producing both holistic overviews as well as offering specific expertise.

In this issue of Highlights you will find a selection of articles describing some of the things that are going on at SSPA. You will find the latest results from work on the tool for energy efficient fleet design and what we are doing with regards to URN “prediction of underwater radiated noise” as well as large area propellers. There’s also an introduction to the Stockholm Bypass project in which SSPA is contracted in the work on future maritime transport solutions.

We have broadened our maritime simula-tion capacity and have rebuilt our simulation facilities, where both the main ship and tugs can be maneuvered simultaneously.

A first workshop has been held in one of the Zero Vision Tool projects, Make A Difference, where the world’s first ship-to-ship LNG bunkering vessel Seagas, the LNG fuelled passenger ferry Viking Grace and Ports of Stockholm were visited and safety issues and regulations were discussed with regards to building a shipping infrastructure for Liquid Natural Gas.

Do not hesitate to contact us, with feedback, comments or questions. We hope you enjoy issue 57 of SSPA Highlights!

Susanne AbrahamssonPresident

Highlights.

Various missionsA simulation program is always tailor-made. If the most efficient solution is a set of fast-time simulations, desktop simulations or even full mission with separately controlled tugs they can all be simulated using SEAMAN, using the same advanced dynamic models of ships and fairways. Sometimes the right solution might also be an incremental one, which starts with desktop simulations and ends with a full mission environment. However all the simulations are performed in different configurations of SEAMAN, with consistency of the different simulations guaran- teed by the use of the same core software and

The SEAMAN simulation tool offers flexibility and rapid response. Here a test of a tug situation at a given time.

Highlights 57/ 2013 – SEAMAN simulations 3

Jim Sandkvist

the same dynamic ship models during the entire project.

To reach a good, optimized solution, close cooperation and dialog between SSPA and the customer is promoted. This also covers exchange of geospatial data, hydrological data, meteoro-logical data, etc. Fortunately, SEAMAN handles all of the common formats for the above data. When modeling ships, SEAMAN has a built-in capability of ship modeling, the SHIPGEN and software, that draws on the thousands of model tests taken at our facilities, as well as the experience of our experts. The SHIPGEN software is completely integrated with SEAMAN. This provides the highest fidelity of modeled ships and environments, used by our experts.

ExecutingThe execution of simulations can take place wherever it is most convenient, either in SSPA’s own simulation lab or at the customer’s office, in order to open up for a wider range of involved representatives.

The environment in which the simulated ships operate is complex and the people participating in the simulations usually have creative ideas that come from the last simulation performed. After a simulation a pilot might say: “We will never get into the harbor using the planned manoeuver, but what if we moved this buoy to that place, and try this maneuver instead. Then the ship might enter safely”. Since these types of request are common, SEAMAN is designed with flexibility for changes, and our simulation experts, together with port representatives, will keep the integrity of the simulations results intact, making sure that the results can still be used to answer the customer’s initial questions.

DeliverablesThe reports from simulations will be focused on the initially defined needs and answers requested. They may focus on operational limits due to weather, the need for tugs, are safety levels improved when using escort tugs versus costs, operational manuals, etc.

SSPA is also fully aware of the importance of who will be the reader; will it be onboard officers? permitting authorities? investors? The answers contain the Pilots and SSPA maneuve-ring experts’ opinions and conclusions on the safety of each simulation, as well as a grade, or Safety Index, automatically calculated by SEAMAN. The Safety Index takes into account available margins expressed as variables such as distance to the edge of fairway, use of rudder, engine and a number of other factors.

Your solution partnerThe SEAMAN simulator is based on decades of development by ship maneuvering experts, who have drawn on decades of model scale tests at our own facilities, customer cooperation and nationally and internationally funded research programs.

Over the past two years SSPA has made major efforts to make this hydrodynamic knowledge more accessible to its customers by developing a more powerful and flexible simulation engine, a more customizable bridge layout, 3D visualiza-tion, and a multitude of other important updates. While we are passionate about the state-of-the-art technology behind these it is not in itself our goal. The goal is, as it has always been, to help customers in their daily work, business and future planning. Having developed these tools just means that we meet clients’ needs and

Vice President. He graduated from Lund University of Technology, Civil Engineering, in 1975 and was then employed

as a research engineer dealing with arctic engineering at Luleå University of Tech- nology, where he also presented his thesis on accelerated ice growth in ship channels. He has been employed at SSPA since 1984, working primarily in the marine environment field.

Contact information: Direct: +46 31 772 90 78Email: [email protected]

questions even better, faster and more efficiently.SSPA is not primarily selling a simulation;

we sell port efficiency, safe operations, cost effective solutions – with all the responsibility that comes from that commitment.

Photo Jim Sandkvist

Port of Rotterdam maneuvres in SSPA´s simulator lab gives higher accessibility for large tankersSSPA was contracted by the Port of Rotterdam to improve the maneuverability for large tankers at the Port and to optimize dredging requirements to improve accessibility for large tankers into the Botlek area. The customer put very high demands on model accuracy regarding vessel behavior, operating in very shallow waters and under stressed tidal and multilevel current varia-tions. Effective and flexible simulation tools giving pilots high accessibility was of the utmost importance. The project was a challenge for SSPA’s experts due to the advanced modeling of stratified current patterns to be carried out using the well-established SEAMAN simulation tool. At the same time, it would be the maiden voyage for SSPA´s new and improved simulation lab.

CurrentsThe current is always a concern when maneuvering a vessel in the Port of Rotterdam and the pilots who work there have extensive knowledge of the current at different times during its 24-hour cycle. In order to improve accessibility and safety for large tankers into the Port of Rotterdam, hypothetical future scenarios had to be analyzed and questions answered: how will dredging change the current situation and how would this affect pilots maneuvering vessels into the area? The Port Authority had developed a very advanced CFD model of the currents in the harbor area. Very high-resolution current patterns in the harbor were presented in four dimensions, time and space.

How much would the proposed dredging increase the maneuverability of vessels entering

4 Highlights 57/ 2013 – Port of Rotterdam

Linus Aldebjer

the port, and what would this mean for accessibility? How many more vessels would be able to enter during a high water period after the dredging?

The key issues were defined and highlighted immediately. Realistic vessel behavior was extremely important for reliable simulation results. Furthermore, due to the huge variation of currents over depth and position at the port area, correct modeling of the currents’ influence on the vessel was another critical issue to achieve that realism. SSPA´s SEAMAN Software and SSPA´s considerable knowledge in modeling shallow water operations could meet the vessel- maneuvering modeling required. The project plan and number of variations to be simulated demanded high flexibility in layouts and conditions, as well as high accessibility.

Customized lab set upThe tool used for simulations at SSPA is SEAMAN, as described earlier in Highlights. SSPA’ s simulation tool has been developed in-house for 30 years, drawing on decades of theoretical and practical research, as well as model scale tests carried out in SSPA’s basins. It is used for all types of simulations in different configurations: fast-time, desktop, full mission, or in any other variant that is needed to solve the customer’s problem. It is truly a bespoke simulation tool.

SEAMAN was used to set up two bridges, one full mission bridge with a 300° view, and one designated tug bridge with a 150° view, both located in SSPA´s simulator lab. In addition to the tug-bridge, up to three automatic tugs controlled by the simulator operator were used.

Project Manager. He studied Engineering Physics at Chalmers University of Technology. Previously he worked as

Software Architect at Saab Underwater Systems, Motala, Sweden. Since he was employed at SSPA in January 2011, he has been leading the work to upgrade SSPA’s simulation tool, SEAMAN. He has also been involved in various research projects developing route optimization and mathematical modeling.

Contact information: Direct: +46 31 772 90 77Email: [email protected]

Highlights 57/ 2013 – Port of Rotterdam 5

The Botlek area of Rotterdam was built up to provide both visual models to the bridge view and input to SEAMAN’s mathematical models of the influence of banks and depths on the vessels. Mo- difications were made in SEAMAN to handle the detailed current model provided by the customer. Two sets of typical simulations were carried out – one with the more detailed current model and one without. Comparison of these two results made it clear that the customer had been correct in their first assumption, correct modeling of the complex current patterns in this area significant-ly improved the accuracy of the simulation. SEAMAN was modified to handle a fourdimen-sional current model. This was the first real time simulation tool able to handle this that the customer was aware of.

SimulationsTwo skilled pilots recruited from the “Loodsweezen” together with a tugboat captain and port representative, carried out the simula-tions in close cooperation with SSPA´s maneuvering experts. Models were created and used of four different types of vessel and two different tugboats.

For each simulation, the opinion of the mariners of the outcome of the simulation was compared with SSPA’s margin-based Safety Index calculations. SSPA’s project manager and nautical experts compiled results to answer the Port of Rotterdam’s initial question: How much will accessibility to the harbor increase with the modifications?

Answering the customer’s questionAfter two weeks of successful simulations and analysis, the results were quantified and a “window of opportunity” for docking was created for each port configuration and type of vessel.

This demanding and challenging project showed the capability

and flexibility of SSPA´s modern simulation lab

The challenge when entering or departing the Botlek area is to maneuver in multilevel currents with major variations due to tidal and weather conditions. On the basis of current information and modeling provided by the customer, various dredging alternatives were modeled in SEAMANand simulated in SSPA´s simulation lab.

This was the answer to the customer’s question. SSPA’s long tradition of simulations, the decades of experience in vessel dynamics, the modifica-tions made to fit this particular project, as well as close cooperation with the customer, all gave credibility to the results. But the ultimate proof was from the professional experts in vessel manoeuvring at the Port of Rotterdam – the pilots operating there. “After the initial calibra-tions, the behavior of the vessels was very realistic,” said Jose Van Rijsewijk, a pilot at the Port.

This demanding and challenging project showed the capability and flexibility of SSPA´s modern simulation lab and well-established modeling re-sources, all of which have been set up to provide

the customer with reliable answers.After SSPA presented the final report the Port of Rotterdam was

confident they had enough background information to make a decision. It was decided to dredge the “thorn” portion of the investigated area, as this would increase accessibility for large tankers

significantly.

6 Highlights 57/ 2013 – STREAMLiNE Large Area Propulsion

Large Area PropellerIn 2012-2013 SSPA carried out a number of model tests in the EU project STREAMLINE, using a new concept called ‘Large Area Propeller’ (LAP). Compared with conventional propeller designs, the LAP is placed behind the transom. This means that the size of the LAP propeller is not limited by the clearance to the hull. This will enable new propeller designs making it possible to achieve very high levels of efficiency, but runs the risk of propeller ventilation.

High levels of efficiency using large propellersAn 8,000 DWT tanker was used for this study. The main idea with the LAP concept was of course to increase the total efficiency of the ship, and the towing tank tests carried out at SSPA confirmed that this is the case. Compared with the reference vessel that used a conven-tional propeller location and design, the LAP concepts showed a power reduction from 6% at low speed (10 knots) up to 17% at the highest test speed of 16 knots. Of course, the increase in total efficiency mainly comes from an increase in propeller efficiency caused by the much larger LAP. The possible drawbacks using such a large propeller is that the propeller tips will fall below the base line, with a greater risk of damage in shallow waters and a greater risk of propeller ventilation.

The first LAP concept design. This design includes a conventional sized rudder. For the final design the rudder was prolonged to keep a straight course without using rudder angles. The structure holding the rudder is preliminary, for functionality in the model tests.

STREAMLINE Stands for STrategic REsearch for innovAtive Marine propuLsioN concEpts (www.streamline-project.eu), and is a EUR 10.9 million project within the EU’s 7th Framework programme’s Sustainable Surface Transport. The project is led by Rolls-Royce, and focuses on propulsion. SSPA Sweden AB is one of 21 partners, and as a work package leader mainly involved in the LAP concept, water-jet development and advanced pods. Other major partners involved in the LAP concept are Chalmers University of Technology, which carried out extensive CFD optimizations and of course Rolls-Royce which was responsible for the design.

Vice President. He graduated (M.Sc.) from Chalmers University of Technology in 1976 and has been employed

at SSPA since then, except for a two-year break. He has been involved in several research and development projects over the years in the field of hydrodynamics, but most of his work has focused on propulsion problems.

Contact information: Direct: +46 31 772 90 66E-mail: [email protected]

Björn Allenström

Highlights 57/ 2013 – STREAMLiNE Large Area Propulsion 7

Ventilation a possible problemEven though propeller to hull clearance is no longer an issue, when placing the propeller aft of the transom, the distance between propeller and water surface will still be an important design aspect. Putting the propeller too close to the waterline can result in problems with venti-lation and in the most extreme cases, propeller blades will even come out of the water. The tests in SSPA’s towing tank have however shown that ventilation will not be a problem in calm water. It seems that the wave pattern behind the ship will have a positive effect, where the propeller is located under a wave peak.

Extensive tests have also been carried out in SSPA’s towing tank and at the Maritime Dyna-mics Laboratory, to examine what will happen when wind waves are present. Propellers will experience tougher working environments at sea. The wave motion, as well as the motion of the ship will vary the flow to the propeller. The flow variation will lead to a corresponding variation in thrust and torque. From the tests, it seems that the LAP will have a higher torque variation, compared to the reference vessel using a conventional propeller location and design. This will be a structural engineering challenge with the LAP concept.

Propeller blade out of the water at seakeeping tests in the Maritime Dynamics Laboratory with 5 m significant wave height.

Tough environment for the propeller in seakeeping tests during ventilation. Only a very slight tip vortex could be detected during the cavitation test.

Almost cavitation freeTests in SSPA’s cavitation tunnel revealed the expected, namely very little cavitation. At design condition only a very slight tip vortex could be detected. Still, however, pressure pulses could be detected at the transom of the ship. The pulses are created by the non-cavitation pressure variations, coming from the propeller. Showing very little cavitation, this solution is to be regar-ded as very environmentally-friendly, as well as having no risk to either propeller or rudder erosion damage.

Will the market agree?We have shown that there is good potential for saving fuel using the LAP concept. We have also investigated and quantified some of the possible risks and engineering challenges. The initial cost for this concept will inevitably be higher, due to its greater size and torque. It will be very inte-resting to see if the market agrees to this greater initial cost, to achieve significant fuel reduction of around 15%.

Project Manager. Graduated with an M.Sc. in Naval Architecture from Chalmers University of Technology in 2010. He

was previously employed as a Graduate Trainee at Rolls-Royce Marine, Norway. He joined SSPA in May 2012 and works mainly with project management, towing tank testing and hull design.


Erik Wiberger

Project Manager. Graduated with an M.Sc. in Naval Architecture from the Royal institute of Technology in 2009. He

previously worked as a Project Engineer for Rolls-Royce Propulsion in Ulsteinvik, Norway. Since being employed at SSPA in November 2011, he has been involved in various research and consultancy projects in seakeeping and maneuvering.

Contact information: Direct: +46 31 772 90 32 E-mail: [email protected]

Martin Alexandersson

8 Highlights 57/ 2013 – Make a Difference

Make A Difference on LNGThe introduction of the SECAs (Sulphur Emission Control Areas) is resulting in some challenges for ship owners and ports trading in the north of Europe. The forthcoming LNG infrastructure in ports provides the opportunity of using LNG as a fuel for ships sailing mainly within SECA areas. This collaboration project on LNG-fuelled vessels, harmonizing with ports, is financed by TEN-T and led by SSPA.

Regulations and guidelines are in place for LNG-fuelled and LNG-laden vessels. The IMO IGF Interim regulations are used for gas-driven ships and IMO IGC code for gas carriers that have been applied for e.g. Seagas, the world’s first LNG bunkering vessel. The regulations for bunkering operations are partly included in the local port regulations.

In order to make LNG more widely used, ship owners have to make sure that the preconditions and requirements in the different ports are conformed with, i.e. that the national or harbor regulations in each port are consistent and that bunkering with the same vessel will be possible in each port. Technical equipment needs to have certain standardization in order to have couplings, vapor return lines, or data links that are compatible.

Economically it is important to ship owners that bunkering can take place while loading/unloading the vessel with passengers or cargo. The priority of safety sets certain limitations and the view of national authorities and harbors varies.

The Make A Difference project aims to research

all these challenges and find suitable solutions for LNG fuelled vessels. Project partners include: Sirius Shipping, Viking Line, DNV, FKAB, the Swedish Shipowners’ Association, PREEM and SSPA. The project is supported by the Ports of Stockholm and Skangass, MAN and the Finnish Shipowners’ Association.

The project consists of six main activities:

Activity 1: LNG certification process for vessels and operatorsThe objective of this activity is to use the IMO guidelines (Resolution MSC.285(86); Interim Guidelines on Safety for Natural Gas-fuelled engine installations in ships) in a real case, where the input from port countries will also be incorporated. The suggested regulations in the draft “International Code of Safety for Gas-fuel-led Ships” (IGF Code) that is under development at IMO will also be used and analyzed during the work.

This work will aim for certification of a specific vessel. This way, the practical problems

and possible conflicting requirements can be identified and suggestions for changes/improvements in the regulations can be made.

A safety assessment will be done based on the suggested design for the EVOlution vessel. This will create a template for future safety assess-ments of new designs. Where assessments show design flaws these will be handled by the design team in their continued work.

From the vessel operator’s perspective a study will be done to identify all rules and regulations relevant for the design of a LNG-fuelled vessel. Since this field is under development within the IMO and at regional/national level, the activity will be going on during the whole project’s duration. The study will be done at international, regional, national and local levels. Safety assessment aspects from sub-activity 1.1 will be incorporated in this sub-activity.

If the assessment above shows that the rules and recommendations are unsatisfactory for the practical design and analysis of a gas fuelled- vessel, these shortcomings will be documented and forwarded to the IMO and EU.

Approx. 100 delegates from 14 countries atten-ded the first Workshop ”Ship-to-Ship bunkering of LNG – Safety in theory and in real life” . The workshop was held in the Port of Stockholm and onboard MS Viking Grace. Pictured here is a visit to the LNG bunkering vessel Seagas.

Project Manager. He graduated as an Engineer in Naval Architecture and Ocean Engineering (Diplom-

ingenieur Schiffbau und Meerestechnik) from Hamburg-Harburg Technical University in 2007 and joined SSPA after graduation. Since then he has been project manager in risk analysis and marine safety projects, as well as ships maneuvering simulation studies. He has also worked with developing SSPA’s simulation, calculation and risk programs and tools.


Johannes Hüffmeier

Highlights 57/ 2013 – Make a Difference 9

Activity 2: Harmonization of the land-based and sea-based regulative and permission application process for LNG bunkeringShip owners face regulations and technical limitations in ports when bunkering LNG. This activity aims at finding ways of harmonizing the regulations and technical solutions for bunke-ring, making the process easier for both ports and ship owners.

From a ship owner’s perspective, the regula-tions and the planning and permit process will be analyzed and described, putting focus on the needs of the ship owner, and the demands for LNG implementation and bunkering.

The expected results from this activity include recommendations and guidelines on actions to be taken to adjust the national system, extending across several national authorities with respon-sibility over land and water issues, and thus harmonizing the demands put on ship owners. The guidelines will also include the land-based infrastructure and the necessary permit process, focusing specifically on the importance of cooperation between all stakeholders in the LNG infrastructure planning process.

Activity 3: Selection and demonstration of environ-mentally-efficient solutions for LNG- fuelled vesselsMany ships built today are far from optimal when it comes to energy efficiency and environ-mental performance. Selecting the most suitable available technology will bring significant improvements.

This activity foresees the preparation of an inventory of available and emerging technologi-es, focusing on LNG. Some of the identified so-lutions will be implemented and demonstrated in the design of the EVOlution vessel. The expec-ted results from this activity include an inventory of existing and emerging environmentally-ef-ficient technologies, a list of feasible solutions and a ranking of technologies from a technical, efficient and financial perspective. Areas where solutions are missing or underdeveloped will be identified. Implementation strategies for the tech-nologies used in designing the EVOlution vessel will give practical experience of the systems in a commercial operation.

Activity 4: Logistic solutions for energy-efficiency of LNG-fuelled vesselsAbout half of the envisaged energy savings in shipping will probably come from operational improvements. Apart from the solutions onboard,

there are many external circumstances affecting operations, e.g. the choice of LNG bunkering method affects the overall logistics and operation of the vessel. In this activity the logistic solutions and their effect on the environmental efficiency will be studied. The aim is to demonstrate ways to plan and perform the transport in the best pos-sible way, taking into account all the stakehol-ders along the route.Two focal areas include:- Analysis of commercial setups and their effect on the transport. Suggestions for alternative setups. - Analysis of different commercial setups for Time Charters, Spot Charters etc. This will include both financial and legal aspects of the transport. The study will concentrate on incen- tives and constraints for transporting in the most energy efficient way. The aim is to find ways of reorganizing the commercial setup and finding a way of distributing the profit from an improved transport solution. - Analysis of technical and organizational constraints for making the ships’ journey time efficient. Suggestions for technical and/or orga-nizational changes are made. The main aim is to shorten the time in port in order to give as much time as possible for sailing, thereby making it possible to reduce speed and thereby reduce the environmental load. The study will deal with possibilities of reducing time losses during the voyage caused by organizational and/or technical shortcomings.

Activity 5: Development of safe and efficient technologies for LNG-bunkering and LNG-fuelled vessels in portThe main obstacle for the introduction of LNG as fuel for ships is the bunkering process and the technical equipment needed. The technical and operational problems and obstacles with LNG bunkering are most often connected to the harmonization of different technical systems.

This activity will identify, analyze and demonstrate technical solutions for efficient and safe bunkering. Risk and safety issues will be analyzed, and possible technical solutions and risk reduction measures will be reviewed.

The following sub-activities are planned:- Identification of suitable bunkering methods and detailed analysis of advantages and disad-vantages of the methods- Identification of problems with each method- Suggestions for solutions to the problems, in-cluding practical demonstration of methods and technical solutions

Assistant Manager of Maritime Operations. He graduated with an M.Sc. in Aquatic and Environmental

Engineering from Uppsala University and has worked as a Response Adviser for the Swedish Coast Guard Headquarters and as Project Officer for Pollution Response at the European Maritime Safety Agency (EMSA). He joined SSPA in 2009 and has managed a number of projects concerning LNG as a maritime fuel, marine pollution response, risk analyses, and environmental management.


Edvard Molitor

Activity 6: Safety assessment regarding bunkering of LNG in parallel with passenger/cargo handlingBunkering must be performed without unneces-sary time loss to make LNG operations competitive. Bunkering processes should take place in parallel with passenger and cargo operations.

A risk assessment of suggested methods for bunkering operations will be performed. Based on this, suggestions for safe, efficient procedures and best practices will be produced. Based on the earlier activities on safe LNG bunkering, a risk assessment will be carried out on parallel bunkering and cargo handling for two cases: one passenger ferry and one tanker.

The study will identify critical parts of the operation and find ways of managing the risks involved.. Based on the risk assessment, and with input from other activities on safe bunke-ring, best practices for bunkering in parallel with passenger/cargo operations will be suggested. These will include organizational and technical recommendations for equipment and standby systems. This work will also lead to recommen-dations for training staff.

Coordination with other relevant projects addressing LNG in shipping is part of the project. More information can be found on the projects website: www.zerovisiontool.com/MaD.

E-Fleet – A strategic decision support tool for energy-efficient fleet designGiven a specific set of transportation needs (e.g. crossing time and cargo amount) and constraints (e.g. physical laws, available resources and max harbor dimensions) the transportation system can be designed more or less effectively. Effectively here referring to how well the solution meets the chosen benchmarking properties (e.g. emissions, costs, or speed) compared with other solutions. By analyzing and thereby understanding the relationship between these basic needs, constraints and their resulting properties, more effective transportation systems can be designed. E-fleet is a tool that can be used to perform such analysis. It is based on a methodology developed for evaluating complex transportation system concepts for the ferry traffic between the Swedish mainland and the island of Gotland.

Initial vessel designThe initial design of a vessel is often referred to as the design process between the basic specified requirements (ship owner) and the contract design (yard). A design spiral is used to illustrate the design of the vessel.

Several prominent naval architects have combined naval architecture with systems engineering and thereby developed good design procedures. These procedures can be seen as road maps for how to complete one lap in the design spiral.

Depending on the size and complexity of the problem these procedures can become time consuming, since things quickly become detailed – general arrangement, ship structure, weight

10 Highlights 57/ 2013 – E-fleet

“E-fleet is a tool for rapidly and resource-

efficiently evaluating transportation systems, either

consisting of a single vessel or a complex fleet consisting

of different ships”

estimations, required propulsion power, cost, updating the general arrangement and so on.

E-fleetE-fleet is a tool for rapidly and resource-efficiently evaluating transportation systems, either consisting of a single vessel or a complex fleet consisting of different ships with diffe-rent operational profiles.

Compared with the design spiral, it completes the first lap and is therefore a helpful tool at the planning stage when determining the holistic design of the transportation system. The

result of an analysis using E-fleet could for in-stance be input variables for an initial design.

Energy efficient ferry traffic to Gotland – A tricky challengeThe tool was initially develo-ped for analyzing the energy needs of different transpor-tation system concepts for the ferry traffic between the

Swedish mainland and the island of Gotland. The traffic to Gotland carries

passengers, passenger vehicles and trailer transport on two different routes. It is

Project Manager. He graduated with an M.Sc. in Naval Archi-tecture from the Royal institute of Technology in

2012. At SSPA, he works with the develop-ment of E-fleet while participating in various ship design and traditional naval architecture- related projects.


Philippe Ghawi

Highlights 57/ 2013 – E-fleet 11

E-fleet simulation showing yearly costs, needed amount of vessels and required installed power for different size of vessels.

characterized by large variations in transportation needs during the year, icy winters and the desire for a top-quality service, referring here to short crossing times and at a high rate. Together with the requirement for an overall cost minimization, designing the most energy-efficient solution, i.e. transportation system, became a tricky challenge.

Different plausible transportation systems with different setups of vessels were specified and evaluated using E-fleet. Total emissions and costs were compared and from that the most suitable concept was found.

MethodE-fleet’s strategy was to replace conventional analytical and physical models, e.g. required

propulsion power, with statistical models. Large databases with information of similar vessels together with knowledge of the trends the data described, laid the foundation for the statistical models.

Here, one statistical model with few input parameters could replace several physical equations that could depend on many more parameters. By doing so, many time-consuming operations could be skipped, while at the same time realistic results could be obtained.

One large Ro-Pax or two smaller fast Ro-Pax ferries plus one slow Ro-Ro?An additional area of application, that is possible due to the rapid and automated format of E-fleet,

is studying the consequence of single parame-ters. By varying parameters and repeating the evaluation in E-fleet, the parameters’ influence on the result can be studied. This can be of interest for parameters that are either left out or not important for the design – or in other words, where there is room for improvement.

Such parameters could range from different mooring alternatives to choosing between one large or several small vessels.

The result of such an analysis is presented in the figure to the left. The figure illustrates the an-nual costs for different vessel sizes (given here in cargo capacity) and amount of vessels for a given operational profile: specific cargo and transpor-tation needs, specific routes, service speed, etc,. The analysis shows that the most economical fleet configuration is obtained for one vessel with a capacity of 800 lane meters.

The conclusion from the example is that the solution is not easy and even quite complex in a rather simple scenario.

Current development Last year E-fleet was awarded funding for further development through the Hugo Hammars fond för sjöfartsteknisk forskning research fund. The goal of the project is to produce a more general model for calculating energy needs given a specific operational profile (route, service speed, installed power, etc.). The purpose has been to cover more types of marine traffic, especially maneuver-intensive traffic, such as smaller archipelago vessels. The project is planned to end in mid-2013 and will be ready for commercial use later in the year.

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Prediction of underwater radiated noise from ship propellersUnderwater radiated noise (URN) has been a concern for naval vessels and specialized quiet vessels for many decades. SSPA has been involved in numerous acoustic-related projects for continually developing various predictive tools, making them available to assist customers in solving problems related to URN. Today, we can see a growing interest in URN from merchant ships as well and we recognize that underwater acoustics is coming out of the military closet.

Growing commercial interest in URNRecent directives outline the need to mitigate underwater noise footprints due to shipping, to prevent negative consequences to marine life:

- In 2008, the International Maritime Orga-nization (IMO) added “Noise from commercial shipping and its adverse impact on marine life” as a high priority item to the work of its Marine Environment Protection Committee (MEPC).

- In 2010, EU Marine Strategy Framework Directive (MSFD) defined indicators where two of them mainly corresponded to shipping noise.

- In 2010, the classification society DNV released a new Silent Vessel Notation Class. Four of these classes are aimed at improving performance of special purpose vessels while the Environmental class is more geared towards giving merchant vessel owners a way of proving to the public and industry that they are trying to improve the green credentials of their vessels.

Thus, there is a growing need to predict ra-diated noise from ships and propellers especially for propellers with cavitation.

Propeller design practiseNaval vessels and research vessels are designed for high cavitation inception speed and low non-cavitating noise; hence, they typically have a large blade area, unloaded blade tips, a high blade number and highly skewed blade design. These measures come at the expense of reduced efficiency.

A merchant ship propeller is optimized for fuel efficiency, which is further stressed by the IMO Energy Efficiency Design Index (EEDI). For merchant ships this means lower blade area and higher tip loading. Thus, the optimum propeller design will have some amount of cavitation. However, excessive cavitation can cause erosion, high pressure-pulses and thrust reduction.

12 Highlights 57/ 2013 – Prediction of underwater radiated noise from ship propellers

A project dedicated to mitigate shipping noise and vibrationThe recently completed EC project SILENV (Ships oriented Innovative soLutions to rEduce Noise and Vibrations, more info at www.silenv.eu) was dedicated to collaborative research on three important aspects of noise related to maritime transport: Machinery noise and vibration on board ships; airborne noise in harbors, and underwater radiated noise (URN). One aim was to deliver a green label proposal with recom-mendations for target noise levels and associa-ted design guidelines. The project consortium consisted of 14 partners from universities, consultancy companies, model basins, research centers and classification societies. The state-of-the-art techniques used for noise prediction and noise abatement were investigated. Within the work package “Modelling”, a benchmark study was carried out for a LNG ship by CETENA and SSPA and the results were compared with the sea trial data. CETENA applied a chain of boundary element methods to predict the tonal noise, whe-reas SSPA compared three computational tools described below.

Crucial to have the flow field predicted correctly Noise signals appear in two different forms: broadband and tonal noise. The noise sources are inherently embedded in the near field flow around the ship’s hull and propeller. For instance, the turbulent boundary layer and the wake of the hull and propeller blades contain largely fluctu-ating shear stresses and vortices, contributing to broadband noise. The inhomogeneity of ship wake results in a periodically varying loading on propeller blades. These periodic loadings cause radiation of tonal noise at blade passing frequen-cies (BPF). Therefore a physically correct reso-lution of these features is essential for a reliable prediction of radiated noise in the far field.

A cavitating propeller generates more noise Cavitation on a propeller contributes to an added level of noise over a wide frequency spectrum. Cavitation noise occurs when the cavity volume changes (e.g. the growth and collapse of cavi-tation). Collapsing cavities cause broadband noise in a frequency range up to 100 kHz. In addition, sheet cavitation produces tonal noise at harmonics of BPF, due to the fact that cavity vo-lume changes with pressure variations when the propeller blade passes through the wake field.

Other contributing factors The radiated noise is influenced by many factors, e.g. the hull form, ship speed and propeller par-ticulars. The resulting noise signature is often a consequence of re-modulation of multiple noise sources and noise does not radiate symmetrically in all directions.

Field measurements of URN are very much affected by the sea environment. In shallow waters the propagation of low frequency signals are prevented. This effect is clearly present in the sea trial data used here. CETENA’s study demonstrates how the first harmonics of tonal noise are modified by the boundary reflection effect due to the existence of a shallow water seabed near the ship.

Tools for predicting URN for ship propellers

1. Model-scale testing: Predicting full-scale pressure fluctuations traditionally relies on model-scale testing. Noise signals are measured in SSPA’s large cavitation tunnel for a fully appended ship model and the results are scaled up to full scale.

2. Potential flow (PRACAL): A Lifting Surface program performs analysis of propeller performance in an inhomogeneous wake first.

Jan HallanderProject Manager. He graduated with an M.Sc. in 1991 in Mechanical Engineering and received his Ph.D.

in Naval Architecture from Chalmers 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, especially with phenomena related to cavitation and noise induced by the propeller.


NOISEGEN is then used to calculate the noise at blade frequency and its harmonics due to blade loading and thickness. The method is a finite-difference approach using two forms of solution to Ffowcs Williams-Hawkings (FWH) wave equation.

3. Semi-empirical modelling (S-E): Semi-em-pirical models were developed at SSPA mainly for naval ships and underwater vehicles at early project stage. An S-E model does not require detailed geometry information of hull and pro-peller. It can be used to estimate both the tonal and broadband noise for propellers with and without cavitation.

4. ANSYS FLUENT: ANSYS FLUENT offers a hybrid approach with three flow solvers of increasing resolution capabilities: an Unsteady Reynolds-Averaged Navier-Stokes (URANS) method, a Detached Eddy Simulation (DES) and a Large Eddy Simulation (LES). The idea behind the hybrid method is to solve the near field flow with a flow solver while the far field noise is computed by integrating FWH wave equation. Predicting vortex cavitation requires better resolution of turbulent structures and flow unsteadiness, which may require an LES or DES solver rather than URANS. The advantage of these methods is that the noise due to the scatter- ing effect of the hull and the broadband noise in the boundary layer can also be predicted.

Selection of tool depends on factors like the aim of investigation, the type of ship and propulsor, propulsor with or without cavitation, eventual constraint on delivery time etc. Semi-empirical modelling and potential flow calculations are the fastest tools for producing results quickly while CFD calculations (FLUENT) take significant-ly longer. The time for model testing lies in between the two methods mentioned above, yet it needs some additional time for model manu-facturing and set-up of the test.

ConclusionsThe tools in the benchmark study are able to predict tonal noise up to the first four blade harmonics to an acceptable level except the semi-empirical model. The hybrid method FLU-ENT captures more harmonics and wider broad-band spectrum. Although potential flow methods are not able to predict broadband noise, they offer very effective alternatives for estimating tonal noise. More results are described in the paper by Hallander et al. “Predicting underwater radiated noise due to a cavitating propeller in a ship wake”, presented at the 8th International Symposium on Cavitation, 2012. It is important to consider and identify the problem related to noise at early design stage, thus avoiding the risk of re-design. It is usually at this stage that the cost-effective and technically beneficial solutions can be achieved.

The total axial wake in front of the propeller at full scale.

The predicted cavity pattern on the full scale propeller

Instantaneous pressure field behind the propeller and hull

Difference in URN level between the non-cavitating and cavitating propeller. The FLUENT prediction shows that a narrow sheet cavitation on blades increases broadband noise by 15~20dB and tonal noise by 5~10dB compared with the non-cavitating case, agreeing well with the sea trial observation where an increase of 20dB broadband noise was attributed to the developed cavitation on blades.

Benchmarking of tools at a far field location H2. URN is expressed as sound pressure level (SPL) at 1m distance from the noise centre (propeller). The vertical lines in the background are multiples of blade passing frequency. The data is relative to reference values for confidential reasons. PROCAL is the abbrevia-tion for CETENA’s methods. PROCAL with seabed reflection effect agrees very well with the sea trial data for the first three harmonics. “PRACAL+ S-E Model” was obtained by adding the cavitation contribution estimated by S-E Model to the PRACAL results for the non-cavitating noise.

Highlights 57/ 2013 – Prediction of underwater radiated noise from ship propellers 13

Da-Qing LiProject Manager. He graduated with an M.Sc. in Naval Architecture from Huazhong University of Science and Technolo-

gy in 1986 and a Ph.D. from Chalmers University of Technology in 1994. He joined SSPA in 1997 and has worked with various projects for propulsion, cavitation/erosion, and shallow water problems using CFD tools and model testing. He has been active in a number of EU projects, presently AQUO and STREAMLiNE, and he is a member of the 27th iTTC Specialist Committee on CFD in Marine Hydrodynamics.


Source Level, Trial vs. Prediction, 19kn with cavitation

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14 Highlights 57/ 2013 – Marine transport in the Stockholm Bypass project

Marine transport in the Stockholm Bypass projectConstruction of the Stockholm Bypass is planned to start in the summer of 2014. 21 km of motorway, (18 km tunnel), will, when finished, connect the southern and northern parts of the Stockholm region. From a shipping perspective, the project is a unique example of the potential for using waterways in large infrastructure projects where more than half of the 19 million tonnes of rock extracted from tunneling will be transported by ships or barges from three temporary jetties. Two of these jetties will also be used for transporting building materials and construction machines by sea. The project is now in the final stages of preparatory work and the last remaining permits are expected in the beginning of 2014, followed by several procurements and a build start next autumn. As support during the preparatory work, the Swedish Transport Administration (Trafikverket) has contracted SSPA as a consultant in matters relating to the marine transport. The assignment includes: risk analyses, evaluation of harbors and ships, costing and developing the marine transport framework.

The Stockholm BypassStockholm is one of the fastest growing regions in Europe. More than 30 000 people move to the region every year and population numbers are expected to increase from 2 million to 2.5 million by 2030. A good labor market and an attractive location are contributing factors. On the other hand, there is a shortage of housing and the transport infrastructure is over capacity.

Particularly vulnerable is the passage over the “Saltsjö-Mälar” cut. This cut naturally separates the region into a northern and a southern section. It is defined by Lake Mälaren to the west and the Baltic Sea to the east. The separation can only be crossed over a few bridges, resulting in a vulnerable traffic system, which in turn obstructs Stockholm from growing as one region. Planning of a new motorway has been underway for

some years under the working title “Stockholm Bypass”. When the motorway is completed in around 2024, roughly 140,000 vehicles per day will have the option of travelling from “Kungens kurva” in the south to “Häggvik” in the north. This distance will take less than 15 minutes compared to the present 30 – 60 minutes. The project is estimated (2009) to cost around SEK 27.6 billion.

The rock is crushed down to fractions of 0 – 150 mm and loaded onto ships using a conveyor system. Construction materials and machines are transported by Ro-Ro ferries. Graphic: Tomas Öhrling

Project Manager. M.Sc. Naval Architecture. He started his career in the Swedish Navy as a deck officer in 2001.

He graduated with an M.Sc. in Naval Architecture from the Royal institute of Technology (KTH) in 2010 and joined SSPA the same year. He mainly works with general naval architecture issues, the development of sea transport systems and risk assessment.

Contact information:Direct: +46 31 772 91 92Email: [email protected]

Torvald Hvistendahl

Highlights 57/ 2013 – Marine transport in the Stockholm Bypass project 15

Interfaces and procurementsConstruction of the Stockholm Bypass is divi-ded into two phases. The first phase comprises establishing a working area and constructing working tunnels and harbors. This phase will take about one year followed by work on constructing the main tunnels. To reduce construction time, a substantial part of the work will be carried out in parallel on seven stretches

of the Bypass. All extracted rock will be trans-ported away by dry cargo ships and/or barges from three of these stretches.

Focusing on marine transport, three basic interfaces with the following specific areas of responsibility can be recognized:

- Receiver (buyer) of extracted rock: provide and be responsible for the harbor where the rock is unloaded

- Contractor first phase: Construct and start up the harbor

- Contractor second phase: Operate the harbor, responsible for marine transport of rock, construction materials and machines. The contractor is also responsible for phasing out the harbor and restoring the surrounding area.

Procuring the two phases and selling extracted rock are separate contracts. Thus, each interface for each stretch might be operated by different companies. In the same way, one company can also operate several contracts. Irrespective of the result of the procurement process, the different areas of responsibility must be sufficiently de-veloped to secure a sustainable transport system over the project’s lifecycle. In this context, SSPA supports the development of a transport concept and a related framework. Examples of tasks are transport analysis, benchmarking of ships, ice recommendations and costing.

Transporting extracted rockThe transport chain starts once tunnel blasting commences. Large pieces of rock will then be crushed to fractions of 0-150 mm and transpor-ted by a conveyor system to the ship. The ship then travels a few hours to local ports in Lake Mälaren and is unloaded by an excavator on the ship deck or by harbor cranes. In connection with the unloading, the deal between the buyer and the Transport Administration is closed. The buyers will then store and process the material into rock products for the local construction industry. A total of 9.5 million tonnes of rock will be transported at sea over a 5-year period. Putting this into perspective, the present cargo volume transported on Lake Mälaren is less than 3 million tonnes annually.

The Stockholm Bypass will consist of 21 km of new motorway linking the southern and northern parts of Stockholm. To reduce environmental impact, 18 km of the road is in a tunnel. Graphic: Tomas Öhrling

Project Manager. He graduated as an Engineer in Naval Architecture and Ocean Engineering (Diplom-

ingenieur Schiffbau und Meerestechnik) from Hamburg-Harburg Technical University in 2007 and joined SSPA after graduation. Since then he has been project manager in risk analysis and marine safety projects, as well as ships maneuvering simulation studies. He has also worked with developing SSPA’s simulation, calculation and risk programs and tools.


Johannes Hüffmeier

SSPA’s vision is to be recognized as the most rewarding partner for innovative and sustainable maritime development. In order to always be able to offer the latest knowledge and best practices, about 20 percent of the company’s resources are engaged in research and development. SSPA was established by the Swedish government in 1940. In 1984 SSPA was established as a limited company, SSPA Sweden AB, and has been owned by the Foundation Chalmers University of Technology since 1994.

SSPA offers a wide range of maritime services, including ship design,energy optimization, finding the most effective ways to interact with othertransportation types and conducting maritime infrastructure studies togetherwith safety and environmental risk assessments. Our customers include shipowners, ports, shipyards, manufacturers and maritime authorities worldwide.

Our three focus areas are:• SSPA functions as the bridge between theory and practice, research and

implementation, the present and the future. The foundation is the ability to provide unbiased expertise, advice, and services to our customers and other stakeholders.

• SSPA ensures sustainable development through proper risk management in close cooperation with the customer.

• SSPA has the financial, environmental, human and technological factors in mind for optimal energy efficiency.

Our headquarters are in Gothenburg and we have a branch office in Stockholm.

To use short sea transport as an integral part of large infrastructure projects is very rare in Sweden. Thus a new dimension is added to both buyer and contractor. Compared with trucks, which can basically be ordered from one day to another, a sea transport system of this type requires lots of preparatory work. New harbors and new fairways require design work as well as cooperation with several authorities such as the Swedish Transport Agency, County Administrati-ve Board and Swedish Maritime Administration.

Risk AnalysisLake Mälaren is the third largest lake in Sweden and a very important national resource. The lake is used for sea transport, fishing, and is a much appreciated recreational area. It is also a very sensitive area with several heritage sites and na-ture reserves. The lake is the primary fresh water source for 2.5 million people.

Thus, the impact of the transport on the environ-ment must be minimized. To cope with this a risk analysis of the sea transport is mandatory. This was performed by SSPA following the IMO FSA (Formal Safety Assessment) methodology. In this methodology the Hazid (Hazard Identification) meeting is a central part. During this meeting several stakeholders were invited to give their opinions about risks and action to reduce risks in relation to project phases, harbors, fairways and operative scenarios. To create a consen-sus about the prerequisites, a Hazid is always preceded with thorough research and analysis of the typical conditions in the area. For this, SSPA has several tools for efficiently compiling and presenting significant data over the actual area. GIS, (Graphical Information System) together with statistics of sea traffic (AIS), accidents, metrology, hydrology and ice, provide compre-hensive tools for visualizing the typical area’s

Traffic intensity taken from AIS statistics.

Excavator on ship deck, one possible solution to unload the extracted rock. Photo Torvald Hvistendahl

The combination of Geographical Information System and AIS data is a powerful tool for evaluating the position of a harbor.

specific conditions. The result from Hazid is then summarized in a matrix and each participant gets the opportunity to rate likelihood and consequen-ce of the risks and also how a specific risk-redu-cing action will change the rating. The results are compared to the risk acceptance criteria and the effect of possible risk reducing measures can be evaluated and suggested for implementation.

Although the risk analysis is a very ‘hands on’ example of an SSPA task in the project, a lot of our work in this project is about supporting the Swedish Transport Administration on a daily basis, e.g. answering questions, participating in meetings, managing contacts with the maritime industry and authorities. With more than 900 years of shared maritime knowledge, SSPA is not only your maritime solution partner, we can also be your maritime supporting partner.

SSPA Highlights is published by: SSPA SWEDEN AB Box 24001, SE-400 22 Göteborg, Sweden. Phone: +46 31 772 90 00 Fax: +46 31 772 91 24Mail: [email protected] Web: www.sspa.seMH 100772-01-00-A

You can also download Highlights at www.sspa.se

16 Highlights 57/ 2013 – Marine transport in the Stockholm Bypass project

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