For several years now, we’ve been researching and testing the effect on fast-planing vessels of a hydrofoil positioned amidships beneath the hull, a.k.a. the Foil Assist.

We were aiming to support a major portion of the vessel’s weight on the foil rather than on its hull at the waterline. The underlying principle wasn’t to achieve full hydrofoiling, but partial hydrofoiling in order to improve performance and seakeeping, much like our Hull Vane®.

Early in the development process, we built and successfully tested a prototype yacht. To achieve our goals, we had to work out how to stabilise a vessel using only one main foil. We were successful, and the patent is now pending.

How does it work?
The Foil Assist is a small, passive, wing-shaped device made of solid stainless steel that we attach amidships beneath a vessel’s hull. We designed it to withstand cornering forces and to damp pitching motions in choppy conditions.

Partially supporting the vessel’s weight on the submerged wing, rather than at the waterline, helps reduce the effect waves have on performance. And because the Foil Assist only partially lifts its hull out of the water, the vessel handles much more like a normal planing vessel (predictability) than a fully hydrofoiling vessel (stringent weight requirements).

The Power of Performance
In partnership with Wajer Yachts, we fitted a Foil Assist to a Wajer 32 S – a fast-planing hull. Combining computational fluid dynamics (CFD) and our expertise in hydrodynamics, we successfully optimised the design still further.

The combination of Wajer 32 S and Foil Assist makes for a far more comfortable ride, as she virtually flies over the waves, even though her aft is still planing. This reduces slamming and spray considerably and increases stability and speed due to less resistance.

Initial research has shown that the Foil Assist reduces fuel consumption by 10 to 20% while reaching top speeds of 45 to 48 knots with a 3 to 6% power reduction.

Shock Absorber
Foil Assist is the next step in increasing speed and efficiency while reducing power requirements for high-speed yachts, fast patrol boats, naval interceptors, sea rescue boats and pilot boats. This makes the Foil Assist an invaluable, future-proof enhancement for all fast-planing hulls.

This new product will be built, sold and marketed by Hull Vane BV, who have years of experience with other submerged foil appendages, including the custom Hull Vane®, semi-custom Hull Vane® and Dynamic Hull Vane®.