Abstract: A vessel designed to operate efficiently as both a catamaran and air cushion vessel can travel at low speed in a catamaran or displacement mode, high speed in an air cushion mode, and amphibiously with the aid of deployable side seals. The vessel includes catamaran hulls and flexible air cushion bow and stern seal systems together with retractable side seals having hinged doors containing inflatable, retractable flexible components. The doors form part of the side seal system in the deployed position, and protect the flexible components of the seal in the retracted position. The arrangement reduces the drag associated with the side seals while the vessel operates in its catamaran or surface effect ship modes, and prevents damage to the seals during operation in the high speeds SES mode.

Abstract: A vessel transfer system utilizes a larger, surface effect vessel with a hull and a cargo deck, having a pressurized volume of air under its hull. The larger vessel cargo deck is lowered relative to a water surface in order to receive a smaller vessel. Lowering is achieved by depressurizing the volume of pressurized air under the hull. Movable propulsors on an air cushion vehicle permit efficient operation under way in an outer position, while minimizing the envelope dimensions for stowage in a well deck, providing clearance from bridges, docks, etc. in an inner position. In the outer position, the propellers operate in more uniform inflow conditions, resulting in improved performance and lower noise levels. In addition, the craft can be arranged to use a full width stern ramp resulting in time saved during cargo loading/unloading. The propellers will be less likely to ingest green water in high sea states.

Abstract: A vessel (10) designed to operate efficiently as both a catamaran and air cushion vessel can travel at low speed (e.g. Froude number (Fn)=0-0.3) in a catamaran or displacement mode and at high speed (e.g. Froude numbers (Fn)=0.3 or more) in an air cushion or dynamically supported mode. The vessel (10) includes molded catamaran hulls (11, 12) with parabolic waterlines, a flexible, air cushion seal system (16, 17), surface piercing propellers (20) and a propulsion system (e.g. combined diesel and gas turbine). There are preferably auxiliary gas turbines for generating lift air pressure. Forward mounted independently stabilizing foils (30), can optionally facilitate ride stabilization and load compensation at high and low speeds. The foils also generate transverse roll forces to improve high speed maneuvering.