Patent ID: 7617793

Claim:
A vessel for operating on a body of water comprising: a non-planing hull having a waterline and a longitudinal direction with a forward portion, an aft portion, and a central portion, the hull configured to have the aft portion with a smaller water displacement relative to a water displacement at the central portion; and a foil affixed to the aft hull portion, and below the surface of the water, and spaced from the hull, the foil having a chord, and a leading edge and a trailing edge relative to a forward direction, wherein the leading edge of the foil is tilted at a downward angle relative to the horizontal, wherein at least half the chord of the foil is behind a vertical line through the location where the aft portion of the hull leaves the water, wherein the foil has a chord and profile in longitudinal cross section, with a configuration to provide a lifting force, the tilt angle of the chord of the foil being measured with respect to the horizontal, and wherein the foil is oriented to provide a continuous, upward, forwardly directed component of the lifting force.