What is a hovercraft skirt?

A hovercraft skirt is a flexible material which hangs down around the periphery of a hovercraft and creates a seal between the underside of the craft and the ground or water surface, thereby containing the cushion of pressurised air that enables the craft to float on a cushion of air.

When the hovercraft's engines are running and lift fans are producing air, some of the air will escape downwards through the skirt, preventing it from reaching the ideal, rigid state required for lift-off.

Some early designs of hovercraft employed a "peripheral jet" arrangement whereby air exhausted from the lift fans was ducted around the skirt perimeter for the purpose of achieving a more complete seal against the ground. Some designs featured skirts divided into discrete "fingers", each of which formed a separate air chamber; these "finger skirts" were claimed to improve efficiency by reducing the risk of pressure loss while also helping to smooth the ride at higher speeds.