Patent ID: 7207285

Claim:
A catamaran surface effect ship for traversing a water surface, comprising a catamaran surface effect hull having a hull baseline, spaced apart hulls connected with a deck having a deck underside, and an integral propulsion system for propelling the hull, a) the catamaran surface effect hull having forward and aft flexible seals that enable pressured air to be trapped in an air space that is positioned generally in between the hulls and in between the seals, b) wherein each hull has a smoothly curved bottom portion connecting to a pair of smooth side portions and absent chines, a propeller shaft, each shaft having a propeller and each shaft positioned above the hull baseline, c) wherein the catamaran hull is operable in two modes, a first low speed mode wherein the hull drops and the propellers are fully submerged and a second high speed mode wherein the hull elevates and the propellers are partially submerged surface piercing propellers; and d) wherein the high speed mode elevates each hull so that the water surface is at a position next to the smoothly curved bottom portion; e) in the low speed mode, the water surface is at a position that wets both smooth side portions of each hull, but is below the deck underside, the low speed mode defined by a Froude number of between about 0 and 0.4.