Calm Water Tests

Calm Water Tests

Calm water resistance tests offer very high accuracy results for the prediction of the power required/speed achieved of the vessel. We offer a number of calm water resistance test services:

  • 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 desired running trim.
  • Optimisation of transom wedges, trim tabs or interceptors.
Preparing a model ship in an ocean basin
Sailing Yacht

Sailing Yacht

The Wolfson Unit offers several hydrodynamic experiment services on sailing yachts and wind assisted vessels including: calm water resistance, hydrodynamic sailing balance, VPP refinement, seakeeping and manoeuvring.

This includes the testing of yachts for the America’s Cup, various Ocean Races and inshore racing yachts, superyachts and sail training vessels. With its strong experience in both sailing yacht and powercraft testing, the Unit is in a unique position to offer model testing on wind assisted vessels.

These tank testing capabilities are fully complemented by our computational fluid dynamics (CFD), wind tunnel and naval architecture software services.

  • Calm water resistance.
  • Appendage Development.
  • Hydrodynamic and Sailplan Balance.
  • Multihulls.
  • Velocity prediction program (VPP) Refinement.
  • Flow Measurement.
  • Seakeeping and Manoeuvring.
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, are 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, 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 – fully instrumented propellers and rudders can be fitted to determine the propulsive coefficients.


Measurement of added resistance, accelerations and wetness at different headings; seasickness incidence and crew performance, stability and seaworthiness in extreme conditions.

Active control device testing

Pitch and roll control systems can be tested to evaluate effectiveness and optimise for both passenger comfort and resistance reduction.

Offshore and Renewable Energy Device Testing

Offshore and Renewable Energy Device Testing

Global warming has necessitated the development of renewable energy devices. The Wolfson Unit has a proud history of improving wind, tidal and wave energy devices. Model testing offers the ability to:

  • Optimise the device performance.
  • Measure the power output.
  • Determine the efficiency.
  • Measure forces in 6 axes.
Offshore Installation Modelling

The installation and maintenance of energy capture devices can often introduce significant problems and limitations upon the overall design due to the environment and the presence of the energy sources to be captured. In addition, these parameters vary around the world, and site specific problems can be encountered. For example, the long swell waves of the Pacific produce a very different loading compared to the extreme tide and shorter waves found on the Normandy coast.

With the increase in size of individual structural elements, the installation can often require novel solutions and greater understanding of the loads and motions involved.

Flow Visualisation and Analysis

Flow Visualisation and Analysis

Delivering improvements in appendage design, bilge keel alignment, flow into propellers and through tunnels to minimise resistance, noise and vibration, and increase propeller efficiency.

Flow Visualisation in the Wind tunnel
Model Fabrication

Model Fabrication

The Wolfson Unit creates bespoke models for use in experiments. We have many years of experience building and testing models to obtain full scale results. We work in house and with expert model builders to provide high accuracy results.

For example we have created benchtop models to model the flow through smoke detectors, sloshing (and subsequent damping designs) in onboard swimming pools and particle dispersion from onboard exhaust outlets and their influence on passenger comfort.

Experimental vs CFD

Experimental vs CFD

The Wolfson unit are experts in both computational fluid dynamics (CFD) and physical modelling, and where appropriate can combine the two to utilise their individual strengths to provide the maximum benefit to the design process. The choice of which method to use depends strongly on the nature of the problem.

Generally experimental methods are excellent at obtaining large sets of highly accurate data, whereas 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 for constructing multiple models.

Unsure which method best suits your project?

Open 60 Model Yacht Test

Related Services

  • Computational Fluid Dynamics (CFD)

    Computational Fluid Dynamics (CFD)

    We have extensive CFD capabilities which complement the experimental testing and other services we provide, offering a cost and time effective solution to hydrodynamic design studies.

  • Product Development

    Product Development

    Dynamometers, custom force and torque sensors, electro-mechanical systems and outboard thrust meters.

  • Wind Assisted Shipping

    Wind Assisted Shipping

    Tailored packages to test and evaluate wind assisted technologies.