Working principles

Forward thrust

The flow of water under a vessel’s stern is often not horizontal, but angled upwards. The Hull Vane® has a horizontal wing profile, which generates lift perpendicular to this flow. The horizontal component of this lift provides a forward thrust force transmitted through the Hull Vane’s struts. The wing’s hydrodynamic profile is such that the thrust it generates is greater than the drag it creates. Hence, the net result is reduced resistance for the vessel as a whole.

Wave reduction

The accelerated flow of water over the Hull Vane’s top surface creates a low pressure region that interacts with the vessel’s wake, suppressing its stern wave in much the same way as a bulbous bow suppresses a vessel’s bow wave. A vessel’s wake or wave pattern correlates with the energy used for propulsion purposes. Suppressing the stern wave therefore reduces fuel consumption. Added benefits are that the noise of the wake is reduced, there is less disturbance to other ships and (naval) ships become less visible.

Trim correction

The Hull Vane® reduces the running trim, keeping the vessel at even keel throughout the entire speed range. Taking the Hull Vane® into account in the design from the beginning, allows naval architects to design a vessel with minimal trim variations. In shallow water the vertical component of the lift significantly reduces the squatting effect, allowing for a higher top speed.

Reduced pitching

When sailing in waves the Hull Vane® dampens the pitching motions. This reduces the added resistance from waves and improves the comfort onboard and the safety of operations such as helicopter landings or the launch and recovery of daughter crafts. Moreover, when the ship is pitching, the Hull Vane® generates more forward thrust. We call it the pumping effect.

Effectiveness

The Hull Vane® is particularly effective when used on medium speed displacement vessels, or expressed in naval architecture terms at Froude numbers between 0.2 and 0.8.

Suitable candidates for a Hull Vane® include coastguard and naval vessels, passenger ships, ro ro ships, expedition cruise ships, fast supply vessels and motor yachts. For these types of vessels, energy savings of between 5% and 20% are typical and in some cases even 25% savings are attainable.