Lateral stabilization device for entirely submerged type hydrofoil craft

In a hydrofoil watercraft comprised of a hull, a steering shaft journaled relative to said hull for steering movement about a steering axis, and a hydrofoil affixed relative to said steering shaft and adapted to be submerged during the operation of said watercraft and providing a hydrodynamic lift to said hull, the improvement comprising means for effecting a steering of said steering shaft in response to the leaning of said hull providing a righting force thereupon by said hydrofoil comprising a flywheel, means for supporting said flywheel for rotation about an axis extending transversely to the axis of the steering shaft and for permitting precessive rotation of said flywheel about an axis substantially parallel to the axis of said steering shaft, and means for coupling said supporting means to said steering shaft for effecting a rotational movement upon said steering shaft in response to the percessive effect of said flywheel.