Vehicles for operating over water

A sidewall gas-cushion marine vehicle, comprising:

• a vehicle body having laterally spaced sidewalls extending longitudinally along the sides of the vehicle body and depending therefrom, the sidewalls having bottoms which, in use, extend into the water;
• movable buoyancy members, each comprising a buoyant portion capable of displacing a relatively large volume of water and a web support portion capable of displacing only a relatively little volume of water, each of the buoyant portions defining relatively wide surfaces extending laterally from the web portions, said surfaces being substantially horizontal in fully submerged operative positions;
• means pivotally connecting said web support portions adjacent the bottoms of the sidewalls of said vehicle, the buoyancy members being movable about axes extending substantially parallel to the longitudinal axis of the vehicle;
• means for lowering the buoyant portions of the members into said fully submerged operative positions extending below the sidewalls for low speed operation, whereby sufficient hydrostatic forces are applied to the fully submerged buoyant portions of the buoyancy members during said low speed operation to provide buoyancy lift for the vehicle and to counter unwanted movements of the vehicle;
• and,
• means for raising said buoyancy members into inoperative retracted positions alongside the sidewalls for high speed operation, whereby the buoyant portions are ineffective.