Abstract: An air cushion vehicle capable of operation over land or water, which includes a hull carrying at least one air supply unit, an outer inflatable member connected to and extending around the entire perimeter of the hull, which supports a flexible skirt system which extends down from the inflatable member, which it is part of, and air under pressure is supplied by the air supply unit to the skirt system in a regulated manner, to provide a balanced cushion at the bow, sides and stern and to prevent decaying of the cushion and ploughing. Self contained ballast apparatus is provided to trim the vehicle.