Patent ID: 6901873

Claim:
A hydrofoil craft comprising at least one hull that lies at least mostly above water, a propulsion system, and at least one strut whose upper end is attached to the at least one hull and whose lower end is attached to a fully-submerged dynamically-lifting hydrofoil, the hydrofoil further comprising a leading edge and a trailing edge, a substantially continuous upper surface and a substantially continuous lower surface, a spanwise discontinuity in each surface near the leading edge for causing a local water boundary layer to separate from each surface, at least one gas source, a gas releaser behind the discontinuity on each surface for forming a cavity that extends rearward along each surface from the discontinuity to a cavity closure region near the trailing edge, a gas flow restrictor connected to each gas releaser for limiting gas released into each cavity and ensuring that each cavity closes ahead of the trailing edge, wherein pressure in the cavity on the upper surface is less than pressure in the cavity on the lower surface, wherein most of the upper and lower surfaces of the hydrofoil lie within the cavities, and wherein each surface in the cavity closure region is shaped for closing the cavity on that side relatively smoothly by minimizing a cavity contact angle between the cavity wall and the surface.