14 Highlights 66 / 2019 – Manoeuvring and seakeeping simulations, and the importance of high-quality data Knowing how a vessel will behave in certain conditions can help answer many questions, for example: • What is the operational window for ship-to- ship transfer? • What size and number of tugs are needed for safe berthing? • Will the vessel roll heavily in the forecasted weather? • In what conditions can the ship be safely moored? • What engine power is required to be on schedule 98% of the time? One way to address these types of questions is to use advanced simulations. At SSPA, we have developed a toolbox, called SEAMAN Simula- tion, which can provide a solution for the issues above and much more. The SEAMAN Simulation toolbox For many decades, experts at SSPA have deve- loped well-known and advanced ship models, which have formed the basis for today’s simu- lations. The SEAMAN Simulation is a versatile manoeuvring and seakeeping simulation toolbox. It is based on a semi-empirical approach. This means that the models that form the simulation system are based on a combination of fundamen- tal physical principals and measurements of the properties to be modelled. This technique is not just used at SSPA, but is the dominant technique used worldwide for real- and fast-time manoeuv- ring and seakeeping simulations. The challenge with the semi-empirical method is that it is highly dependent on the quality of data that the models use. Access to relevant and validated mathematical models is always an im- portant factor for successful simulations. SSPA’s models originate from our comprehensive data- bases derived from model tests conducted over the last 75 years. Thanks to SSPA’s test facilities, and the development and use of CFD, such as Shipflow from Flowtech International, we have access to extremely good data which supports the simulation models. Data from a variety of areas are compiled in SEAMAN and this has resulted in a wide range of applications such as: • Manoeuvring prediction • Port and fairway manoeuvring studies • Seakeeping – motion and acceleration • Assessment of roll prevention devices, such as stabilising fins and anti-roll tanks • Monte Carlo simulations: a fast-time simu- lation where environmental and operational conditions are randomised according to statistic distributions • Mooring safety assessment • Ship-to-Ship operations • Operation of ships in locks and narrow canals • etc. Experts cooperate closely with clients For each simulation assignment, SSPA communi- cates with the client to ensure that the simulation has the right level of details regarding both accuracy and cost-efficiency. To ensure the app- ropriate level, there are several areas that SSPA will tailor to the client’s needs. Depending on where a project is in the design phase, delivery time, budget and precision requirements for the models, our experts can select what data sources shall be used. If a short delivery time is requested, we can use parametric data from our databases for ship resistance, manoeuvring and seakeeping pro- perties. If the design details must be accurately reflected in the simulation model, a physical model test and/or CFD computation are recom- mended to determine the parameter input and model validation. Manoeuvring and seakeeping simulations, and the importance of high-quality data Simulations are an efficient tool for gaining valuable insights for decision-making. To perform high-quality ship simulations, high-quality input data is required. Without good input data, the output from the simulations will not be a reliable source of support for decision-making. Thanks to SSPA’s test facilities, and the development and use of Computational Fluid Dynamics (CFD), we have access to extremely good data which supports the simulation models in the SEAMAN Simulation toolbox. Example of CFD computation of flow field around a ship in turn with rudder to starboard.
Transcript
14 Highlights 66 / 2019 – Manoeuvring and seakeeping simulations, and the importance of high-quality data
Knowing how a vessel will behave in certain conditions can help answer many questions, for example:• What is the operational window for ship-to-
ship transfer?• What size and number of tugs are needed for
safe berthing?• Will the vessel roll heavily in the forecasted
weather?• In what conditions can the ship be safely
moored?• What engine power is required to be on
schedule 98% of the time?
One way to address these types of questions is to use advanced simulations. At SSPA, we have developed a toolbox, called SEAMAN Simula-tion, which can provide a solution for the issues above and much more.
The SEAMAN Simulation toolbox For many decades, experts at SSPA have deve-loped well-known and advanced ship models, which have formed the basis for today’s simu-lations. The SEAMAN Simulation is a versatile manoeuvring and seakeeping simulation toolbox. It is based on a semi-empirical approach. This means that the models that form the simulation system are based on a combination of fundamen-tal physical principals and measurements of the properties to be modelled. This technique is not just used at SSPA, but is the dominant technique used worldwide for real- and fast-time manoeuv-ring and seakeeping simulations.
The challenge with the semi-empirical method is that it is highly dependent on the quality of data that the models use. Access to relevant and validated mathematical models is always an im-portant factor for successful simulations. SSPA’s models originate from our comprehensive data-bases derived from model tests conducted over the last 75 years. Thanks to SSPA’s test facilities, and the development and use of CFD, such as
Shipflow from Flowtech International, we have access to extremely good data which supports the simulation models.
Data from a variety of areas are compiled in SEAMAN and this has resulted in a wide range of applications such as: • Manoeuvring prediction• Port and fairway manoeuvring studies• Seakeeping – motion and acceleration• Assessment of roll prevention devices, such
as stabilising fins and anti-roll tanks• Monte Carlo simulations: a fast-time simu-
lation where environmental and operational conditions are randomised according to statistic distributions
• Mooring safety assessment• Ship-to-Ship operations• Operation of ships in locks and narrow canals• etc.
Experts cooperate closely with clientsFor each simulation assignment, SSPA communi-cates with the client to ensure that the simulation has the right level of details regarding both accuracy and cost-efficiency. To ensure the app-ropriate level, there are several areas that SSPA will tailor to the client’s needs. Depending on where a project is in the design phase, delivery time, budget and precision requirements for the models, our experts can select what data sources shall be used.
If a short delivery time is requested, we can use parametric data from our databases for ship resistance, manoeuvring and seakeeping pro-perties. If the design details must be accurately reflected in the simulation model, a physical model test and/or CFD computation are recom-mended to determine the parameter input and model validation.
Manoeuvring and seakeeping simulations, and the importance of high-quality dataSimulations are an efficient tool for gaining valuable insights for decision-making. To perform high-quality ship simulations, high-quality input data is required. Without good input data, the output from the simulations will not be a reliable source of support for decision-making. Thanks to SSPA’s test facilities, and the development and use of Computational Fluid Dynamics (CFD), we have access to extremely good data which supports the simulation models in the SEAMAN Simulation toolbox.
Example of CFD computation of flow field around a ship in turn with rudder to starboard.
Erland WilskeSenior Specialist, Simulations
Erland graduated with MSc in Electronic Engineering from
Chalmers University of Technology in 1988. After graduation, he worked on research in opto-electronic sensors and developing software for cargo handling systems. He joined SSPA in 1994 and, since then, he has been involved in projects linked to the development and use of ship simulation tools.
Fredrik OlssonSpecialist, Simulations & Algorithms – Core Developer
Fredrik has an MSc in Naval Architecture from
Chalmers University of Technology. After graduation, he worked with offshore installa-tions at Technip Norway, participating in the preparation and operational phases of the Snøhvit field. After joining SSPA in 2015, he is now in charge of the development and maintenance of SSPA’s simulation tools. He also coordinates and maintains the soft - ware development infrastructure.
Using the correct input will give the correct outputShip model tests in SSPA’s Towing Tank, such as resistance and self-propulsion tests, provide important input data: resistance curve, wake fraction, trust deduction, speed-power prediction, etc. Using these tests, together with propeller open water tests where propeller thrust and torque characteristic are measured in different working conditions, an accurate simulation model of the propeller and hull in calm water can be obtained.
If wave performance data are needed, the wave makers at the end of the towing tank allow for tests to be carried out with head-on and following waves. These measurements provide information on added resistance in waves that can be used in the simulations. Along with wave statistics and engine data, these provide assessments of route performance in different operational profiles.
If manoeuvring properties are needed, for example for harbour manoeuvring prediction, captive tests in the towing tank are one way of obtaining ship data for the manoeuvring properties. The results are direct measurements of manoeuvring coefficients for hull and steering devices, including propeller side forces.
SSPA’s Maritime Dynamic Laboratory (MDL) is a facility that contributes to the important input for the simulation toolbox. Several syste-matic test series have been carried out in order to formulate models for manoeuvring in confined water such as bank and canal effects, and shallow water effects, including squat prediction. The most common tests are standard manoeuvring tests, such as turning circle and zig-zag tests, and seakeeping. The results of these tests can be used to tune and validate simulation models.
With the above high-quality input data, the simu-lation models can be used for predicting a wider range of test scenarios and producing complete manoeuvring documentation (e.g. a manoeuvring booklet according to IMO 601).
The seakeeping tests are used in the same way to validate and tune the model, and to expand the test matrix to include different speeds, headings, wave conditions, etc.
With high-quality input data, the simulation models can be used for predicting a wider range of test scenarios and producing complete manoeuvring documentation.
Maritime Dynamic Laboratory (MDL) contributes with important inputs to the simulations. In this ex-ample we perform tests with a free-sailing tanker in a generic S-shaped fairway with sloped banks.
operations safer and more profitable, and they will become more successful as a crew, owners or operators.
Preparation and execution of the simulations are critical, but despite being done accurately, the results can be misleading if the input data are incorrect. If this is the case, incorrect con-clusions will be drawn, which can lead to costly design changes.
Over the years, SSPA has created tools and methods to ensure that both quantitative and qualitative results of the simulations can be reported to the client in a concise manner. We are now taking manoeuvring simulations online, providing an intuitive web-based interface for easy access to a powerful tool. Contact us to find out more.
16 Highlights 66 / 2019 – Manoeuvring and seakeeping simulations, and the importance of high-quality data
SSPA is a world-leading maritime knowledge-based company. SSPA has the vision to be recognised as the most rewarding partner for innovative and sustainable maritime development. Based on our clients’ reality, we create sustainable solutions to meet their challenges.
Through commitment, integrity, insight and expertise, we facilitate our customers’ path to success.
SSPA is a dedicated partner that offers a wide range of maritime services,
including ship design, energy optimisation, finding the most effective ways to interact with other types of transportation, and conducting maritime infrastructure studies together with safety and environmental risk assessments.
Our experts have a broad range of knowledge and profound expertise, and we use our resources such as databases, analysis and calculation capa-bilities, laboratories, collaborative platforms and skills to create value.
You can download SSPA Highlights at www.sspa.se
According to EU’s data protection regulation we need your consent to send you SSPA HighlightsPlease give us your consent and choose the way you would like to receive your issues of the magazine. Fill out the form at our website and choose between digital editions distributed by e-mail or paper editions distributed by post. Use the form at www.sspa.se/highlights
We have reviewed our distribution as part of adapting to the data protection regulation GDPR*. We want you to enjoy and benefit from our magazine with the knowledge that we have fair information practices to protect your data. You can unsubscribe at any time by emailing [email protected]
* The General Data Protection Regulation (GDPR) (Regulation (EU) 2016/679) is a regulation by which the European Parliament, the Council of the European Union, and the European Commission will strengthen and unify data protection for all individuals within the European Union (EU).
We need your
consent!
By comparing the result with selected criteria and making projections based on an expected operational profile, the ship’s operability and overall seakeeping performance can be obtained.
Data from a variety of areas have been compiled in SEAMANSimulations are an efficient tool for obtaining a wide range of data regarding ship operations and ship handling, and the output can directly support ship owners, operators, harbour masters, etc. in their decision-making. As a ship designer, it is wise to ensure that manoeuvring and seakeeping properties are within acceptable limits at the design stage to avoid unnecessary surprises that can be extremely costly if not dealt with in time. Knowing how vessels will behave in certain conditions helps our clients to make the correct decisions. This knowledge will make their
We are now taking manoeuvring simulations online, providing an intuitive web-based interface for easy access to a powerful tool.
