Abstract: Cushion sealing at the rear of an air cushion vehicle comprises a flexible skirt that is attached to rigid body structure of the vehicle so as to extend downwardly therefrom and define a plurality of inter-communicating inflatable compartments positioned one above the other. These inflatable skirt compartments communicate by way of a first duct with a source of pressurized air on the vehicle, and by way of a second duct with cushion space at the underside of the vehicle. The second duct offers low impedance to the transfer of air between the skirt compartments and the cushion space, whereby in operation, when the skirt is deflected, air transfers from the skirt compartments to the cushion without any substantial rise in the skirt inflation pressure, which would tend to increase the stiffness of the skirt.