Lab 04
Hydrodynamic Test Tank
Validating performance before the first full-scale prototype
Why tank-test a small boat?
It is a common misconception that hydrodynamic testing is reserved for ocean-going ships. In reality, the performance of a small planing hull —such as a 4— m RIB —is just as dependent on its underwater shape as a tanker is on its bulbous bow. Trim angle, wetted surface area, spray generation, and ventilation all have a dramatic effect on speed, fuel consumption, and ride comfort. At Aquafarer, we operate a dedicated hydrodynamic test tank that allows us to quantify these effects at model scale —before committing metal and fabric to a full-size prototype.
Testing at model scale (typically 1:3 to 1:5) gives us the ability to iterate hull shapes rapidly and cost-effectively. A week in the tank can generate the same performance data that would require months of full-scale trial-and-error —and at a fraction of the cost.
Facility specifications
| Parameter | Specification |
|---|---|
| Tank dimensions | 35 m (L) × 3.5 m (W) × 1.8 m (D) |
| Towing carriage | Electric servo-driven, max speed 12 m/s (23 kn), speed accuracy ± 0.5 % |
| Wave generator | Flap-type, programmable regular & irregular sea states, Hs up to 0.3 m at model scale |
| Instrumentation | 6-component dynamometer (resistance, side force, yaw moment), accelerometers, inclinometers, wave probes |
| Data acquisition | Sampling at 1000 Hz per channel, real-time display + post-processing suite |
| Model fabrication | In-house CNC milling and 3D printing for model hulls up to 1.8 m LOA |
Our test programme
A standard hull development programme in our tank follows this sequence:
- Model build —A 1:3.5 scale model is CNC-machined from high-density foam and glassed for rigidity. Weight and CG are adjusted to match Froude-scaled full-load condition.
- Resistance runs —The model is towed at 8-10 speeds spanning the operating range. Total resistance is measured and decomposed into frictional and residuary components using the ITTC-1957 method.
- Trim & sinkage measurement —Running trim and sinkage are recorded at each speed. An optimal trim angle of 4-6° for planing hulls is the target.
- Wake survey —Transverse wave cuts are measured at two speeds to assess wave-making resistance and identify transverse wave interactions that could cause stern interference.
- Seakeeping (optional) —Head-sea and following-sea runs in regular waves to measure added resistance, vertical acceleration, and slamming probability.
- Data analysis & recommendations —A full report is delivered with comparative charts, speed/power curves, and specific design recommendations for the full-scale hull.
Typical Tank Test Results —Resistance vs Speed (RIB 450 hull, 1:3.5 scale)
Model-scale resistance (N) at Froude-scaled speeds. Full-scale power prediction follows the ITTC-1978 performance-prediction method.
Expert team
Our tank is operated by a hydrodynamicist with a PhD in naval architecture and 8 years of towing-tank experience at a major European maritime research institute. He is supported by a technician who prepares all models and instrumentation. The team follows the ITTC (International Towing Tank Conference) Recommended Procedures to ensure that every test is repeatable, traceable, and internationally defensible.
Tank-testing for custom hull development
Our tank is not only used for house-designed hulls —we regularly run test programmes for clients who want to validate a custom hull shape or investigate a performance issue:
- Hull-form comparison —Two or more candidate hull shapes tested under identical conditions, providing an objective drag/speed/stability comparison to inform your design choice.
- Appendage optimisation —Interceptor plates, spray rails, trim tabs, and strakes can be tested in various configurations to quantify their individual contribution to drag reduction.
- Engine-matching study —Resistance data is converted to a power-prediction curve, allowing you to select the optimum engine horsepower for your target speed and payload.
Why test with us?
We do not just give you a set of raw numbers. Our reports translate tank data into actionable engineering recommendations: "Raise the spray-rail by 8 mm to reduce wetted surface at cruise speed", "Increase deadrise at the transom by 3° to reduce slamming acceleration", or "Move the longitudinal centre of gravity 150 mm aft for improved planing attitude". You leave with a clear understanding of what to change and why.
Our tank is also available for independent third-party testing on a fee-for-service basis. If you are developing a hull and want an unbiased, professionally executed hydrodynamic assessment, we welcome your enquiry.
Book a tank test session
Whether you need a full development programme or a single comparative test, we can accommodate your schedule.
Contact our hydrodynamics team