Abstract: A drive train for an air thrust propulsion boat which has a propeller encircled by a noise reducing and efficiency increasing shroud. The shroud and propeller rotate about a generally vertical axis providing steering control for the boat. A plurality of rudders are attached to the rearward side of the propeller shroud in the slipstream of the propeller and serve as a secondary means for steering the boat. An engine which powers the propeller is remotely positioned from the propeller giving the boat a lower center of gravity. Connected to the engine is an automotive type automatic transmission which gives the boat both forward and reverse motion capabilities.

Abstract: A boat hull for an air thrust propeller driven boat is provided that includes a double hull construction along at least a portion of the length of the hull. The lower member of the double bottom portion of the hull is provided with a plurality of apertures. Air can be supplied to the hull apertures from two air sources, one of which is exhaust gas emitted from the exhaust manifolds of an internal combustion engine, and the other of which is air diverted from the slipstream of a propeller which is powered by the internal combustion engine. The air from the two air sources is channeled to the hull apertures, which direct the air against the water beneath the hull, thereby forming an air boundary layer beneath the boat to reduce friction between the underside of the boat and the underlying water.