The hovercraft hovers by creating a cushion of air with enough pressure to the weight of the craft and the passenger. The fan constantly blows air molecules into the cushion. The cushion inflates, and there are a couple of holes in the cushion that allows some air molecules to escape so the cushion doesn't explode from the pressure. The trick to get the craft to hover is to have the air molecules exert greater pressure or force than the weight of the craft. The air pressure needed to lift the hovercraft equals the weight of the craft and the passengers divided by the area. Pressure = Force / Area. It seems like pressure and area are inversely proportional, however, the larger the surface area, the greater the weight of the craft and therefore more pressure would be needed. Also the larger the area, the greater drag or resistance on the craft is created.