Our Services
The Wolfson Unit offers scale model towing tank and model basin tests to assess the performance of full-scale motor and sail powered vessels. Models are built to exacting standards and tested using specialist instrumentation and dynamometry, providing accurate experimental data to support vessel design, development and performance assessment.
Our experience spans a wide range of vessel types, including:
- Wind assisted ships
- Sailing and motor yachts
- Naval vessels
- Fishing vessels
- Crew transfer vessels
- Hovercrafts
- Amphibious vehicles
- Offshore structures
What is Model Basin and Towing Tank Testing?
Towing tanks and model basins are different facilities used for different types of hydrodynamic testing. However, people within the marine industry will often use the terms interchangeably when discussing ship model testing. Understanding the distinction helps determine which testing method is most appropriate for the questions a project needs to answer.
Towing Tank Testing
Towing tanks are generally very long and slender tanks of water which have a moving carriage rolling over the top of them. The model is towed through the water via a direct connection with the carriage. This means that the model travels at a constant speed and various sensors can be used to measure variables such as resistance, pitch and heave.
Wave makers can be used to create regular and irregular seas to evaluate the seakeeping and added resistance of the design. We also do other kinds of testing in our tank including moored tests, free-running tests and self-propulsion tests.
Model Basin Testing
Model basins are large water tanks, similar to a very large swimming pool, used for testing vessel performance. Trials are typically conducted using free-running models: remotely controlled scale replicas of full-size vessels that propel themselves rather than being towed.
Waves are generated by the basin’s wavemakers, while a combination of motion capture systems and onboard sensors is used to measure the vessel’s seakeeping performance. Manoeuvring capability is also assessed through a series of standardised tests.
Unlike a towing tank, which is generally limited to head and following seas, a model basin allows vessels to be tested across a wide range of wave headings, providing a more comprehensive assessment of their performance in realistic sea conditions.
Flexible Approach
Our engineers communicate directly with clients throughout the test programme, allowing flexibility to focus on the areas that provide the most useful information for each project.
Our Testing Services
Calm Water Tests
Calm Water Tests
Calm water resistance tests offer highly accurate results for predicting the power required or speed achieved by a vessel. Testing can be undertaken across a range of operating conditions to provide a detailed understanding of resistance and performance.
We offer a number of calm water resistance testing services, including:
- Measurement of resistance and effective power at a range of speeds, displacements and trims
- Improvements to spray rails, knuckles and chines
- Trim optimisation by assessing the optimal positioning of the Longitudinal Centre of Gravity to achieve the desired running trim
- Optimisation of transom wedges, trim tabs or interceptors
The resulting data can be used to refine vessel designs, investigate performance and support powering predictions before progressing to full-scale implementation.
Resistance and Propulsion Testing
Resistance and Propulsion Testing
Resistance and propulsion testing form a key part of many towing tank testing programmes, providing data on vessel resistance, effective power requirements and propulsion efficiency across a range of operating conditions.
Testing can support:
- Resistance and powering assessments
- Propeller performance investigations
- Hull optimisation studies
- Performance comparisons between design variations
- Efficiency improvements
Propulsion testing can also be undertaken using fully instrumented propellers and rudders to determine propulsive coefficients.
By assessing resistance and propulsion experimentally, designers can obtain reliable performance data to support design development and performance prediction.
Sailing Yacht
Sailing Yacht Model Testing
The Wolfson Unit offers several hydrodynamic testing services for sailing yachts and wind assisted vessels, including calm water resistance, hydrodynamic sailing balance, VPP refinement, seakeeping and manoeuvring.
Our experience includes testing yachts for the America’s Cup, various Ocean Races and inshore racing yachts, as well as superyachts and sail training vessels. With strong experience in both sailing yacht and powercraft testing, the Unit is in a unique position to offer model testing for wind assisted vessels.
Testing can include:
- Calm water resistance
- Appendage development
- Hydrodynamic and sailplan balance
- Multihull performance
- Velocity Prediction Program (VPP) refinement
- Flow measurement
- Seakeeping and manoeuvring
These tank testing capabilities are complemented by our Computational Fluid Dynamics (CFD), wind tunnel testing and naval architecture software services.
Free Running Tests
Free Running Tests
Radio-controlled models, built and equipped by the Wolfson Unit and operating in open water or a seakeeping basin, can be used for a variety of experiments.
Recent advances in rapid prototyping have enabled affordable and representative testing of vessels with water jet propulsion, surface piercing propellers, IPS drives and azimuthing pods. These propulsion systems can be used to perform a number of tests on free-running models, including:
- Manoeuvring and directional stability trials such as Dieudonne spiral tests and zig-zag manoeuvres
- Docking in high winds and use of bow thrusters
- Testing of complex or innovative propulsion systems
- Seakeeping and motions in irregular seas
- Coupled roll and yaw stability at high speed
- Broaching tests
- Propulsion testing with fully instrumented propellers and rudders
Free-running ship model testing allows vessel behaviour to be investigated without the constraints of a direct connection to a towing carriage, making it particularly useful for manoeuvring and dynamic performance studies.
Seakeeping
Seakeeping
Seakeeping testing is used to investigate how vessels respond to waves and challenging operating conditions. Measurements can include added resistance, accelerations and wetness at different headings, alongside seasickness incidence and crew performance, stability and seaworthiness in extreme conditions.
Testing can investigate:
- Added resistance in waves
- Vessel motions and accelerations
- Performance at different headings
- Crew comfort and seasickness incidence
- Stability and seaworthiness
- Behaviour in extreme conditions
These experiments provide designers and operators with data to understand vessel behaviour beyond calm water performance and assess how a design is likely to respond in realistic sea conditions.
Active Control Device Testing
Active Control Device Testing
Pitch and roll control systems can be tested to evaluate their effectiveness and optimise performance for both passenger comfort and resistance reduction.
Testing active control devices alongside vessel motion measurements allows their effect on seakeeping performance to be assessed experimentally as part of the wider model testing programme.nce and assess how a design is likely to respond in realistic sea conditions.
Offshore and Renewable Energy Device Testing
Offshore and Renewable Energy Device Testing
The Wolfson Unit brings decades of expertise in the hydrodynamic testing of wind, tidal and wave energy devices. We offer access to a range of testing facilities, including towing tanks and flumes, with varying capabilities to suit specific project requirements.
These facilities enable the modelling of waves and currents, supporting experimental investigations for a variety of offshore systems, including:
- Floating Offshore Wind Turbines
- Deployment strategies for wind turbines and other offshore assets
- Floating Solar Farms (Floatovoltaics)
- Tidal Turbines including PD IEC TS 62600‑202:2022 stage 1 and 2 testing services
- Wave Energy Converters
- Devices ranging from micro-generators to full-scale platforms
Our experimental testing environment allows developers and designers to evaluate a comprehensive range of parameters to inform and de-risk the development process. These include:
- Device performance optimisation
- Power output measurement
- 6-DOF force and moment analysis
- Calculation of motion damping coefficients
- Acceleration and motion tracking
- Multi-body interaction analysis, including motions and forces
- Mooring and towing force measurement
- Performance assessment in extreme sea states
- Slamming pressures and structural load analysis
- Green water and overtopping phenomena
- Modelling of ballasting and installation operations
This testing capability enables early-stage modelling of installation, maintenance and operational performance, providing critical insights before progressing to large-scale demonstrations or full deployment. insights before progressing to large-scale demonstrations or full deployment.
Flow Visualisation and Analysis
Flow Visualisation and Analysis
Flow visualisation and analysis, including wake surveys, can provide valuable insight into the behaviour of water around a vessel, its appendages and propulsion systems.
These techniques can support improvements in appendage design, bilge keel alignment, flow into propellers and flow through tunnels, helping to minimise resistance, noise and vibration while increasing propeller efficiency.
By making flow behaviour visible, experimental testing can help identify the causes behind performance characteristics and support targeted design refinements.
In addition to traditional flow visualisation, we offer Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV) to provide highly detailed measurements of flow behaviour. These advanced optical techniques capture the movement of seeded particles within the water, enabling engineers to identify flow separation, vortices, turbulence and other complex phenomena around hulls, appendages and propulsion systems. The resulting data supports design optimisation, computational fluid dynamics (CFD) validation, and improvements in efficiency, manoeuvrability, noise and vibration performance.
Model Fabrication
Model Fabrication
The Wolfson Unit creates bespoke models for use in experimental investigations. We have many years of experience building and testing models to obtain full-scale results and work both in-house and with expert model builders to provide the accuracy required for engineering studies.
Our model fabrication capability extends beyond conventional ship model testing. Projects have included benchtop models to investigate flow through smoke detectors, sloshing and subsequent damping designs in onboard swimming pools, and particle dispersion from onboard exhaust outlets and its influence on passenger comfort.
This breadth of experience allows the physical model to be developed around the engineering problem being investigated rather than restricting testing to standard vessel configurations.
Experimental vs CFD
Experimental vs CFD
The Wolfson Unit are experts in both Computational Fluid Dynamics (CFD) and physical modelling. Where appropriate, the two approaches can be combined to utilise their individual strengths and provide maximum benefit to the design process. The choice of which method to use depends strongly on the nature of the problem.
Experimental methods are particularly effective at obtaining large sets of highly accurate data. CFD provides a greater understanding of the flow behaviour behind the results and can be useful for comparing the relative merits of geometry variations without the need to construct multiple physical models.
Combining physical testing and CFD can therefore provide both experimental performance data and detailed insight into the flow behaviour responsible for that performance.
Unsure which method best suits your project?
Help and Support
If you need any support with your project, please get in touch.
Related Services
-
Wind Tunnel Testing
The Wolfson Unit offers several wind tunnel experiment services including: measurement of aerodynamic forces and moments, flow visualisation and other measurement techniques (e.g. LDA and PIV).
-
Computational Fluid Dynamics (CFD) Consultancy
We provide computational fluid dynamics consultancy for complex hydrodynamic and aerodynamic engineering problems, complementing our experimental testing services.
-
Full Scale Trials and Instrumentation
Measurements of vessel while completing sea trials. 6 axis motions, forces, moments, accelerations, temperatures, pressures, and engine data.
Frequently asked questions
What is the towing tank test procedure?
A typical programme runs in four stages. We agree the test objectives and the measurements needed with you directly. We then build a scale model to our own standards, either in house or with expert model builders, and fit it with the appropriate dynamometry.
The model is tested across the agreed range of speeds, displacements and trims, with the programme kept flexible so it can be adjusted as results come in. Finally the data is scaled to full size, analysed and reported. Your engineers deal with you directly throughout rather than through an account manager.
What is the difference between a towing tank and a model basin?
People in the industry often use the terms interchangeably, but they describe different facilities. A towing tank is a long, narrow tank of water with a carriage running over the top. The model is towed through the water via a direct connection to the carriage, so it travels at constant speed while sensors measure variables such as resistance, pitch and heave, and wave makers generate regular and irregular seas for seakeeping and added resistance work.
A model basin is a large, wide basin of water, not dissimilar to a big swimming pool, where we normally test free running models: remote control scale replicas which propel themselves rather than being towed, measured with a motion capture system, so their heading and speed vary as they encounter waves in the same way the full scale vessel’s would. Both facilities have their advantages, and we advise clients on which methods will answer the questions they are asking.
What scale of model is used for tank testing and how are results scaled up?
For towing tank testing our models range from 1m to about 5m. We choose the scale factor based on a number of variables, including the speed of the vessel, its displacement and the magnitude of resistance we expect it to produce.
Results are scaled to full size using a mixture of industry standard ITTC approaches and methods developed and validated in house over our sixty year history, based on Froude scaling in which the wave making and viscous components of resistance are scaled separately.
Where is Wolfson’s towing tank and which facilities are available?
We test predominantly at the University of Southampton’s Boldrewood towing tank, just downstairs from our office: a 138m long, 6m wide and 3.5m deep tank of water with a driven carriage moving at speeds up to 10 m/s. Up to eight people can ride aboard the carriage along with our sensors and data acquisition equipment, and a wave maker at one end generates a range of sea states.
Free running tests are conducted in the QinetiQ Ocean basin, 122m by 61m and 5.5m deep, with a motion capture system and a 122 element wavemaker. On the rare occasion these cannot accommodate what we are trying to achieve, we can test at other facilities across the UK and, within a reasonable radius, in Europe.