A hovercraft is quite simply a vehicle which is wholly supported on a cushion of air supplied by a powered fan mounted on the craft. The cushion of air created by the fan is retained beneath the craft by a flexible extension to the craft structure known as the skirt. The skirt is attached to the outer edge of the hovercraft and is usually made from a thin plastic coated fabric.
Forward motion is achieved by thrusting some of the air backwards, usually by means of a ducted fan.
Previously, separate engines were used to power separate thrust and lift fans but currently the integrated craft using a single fan for lift and propulsion is proving very popular with amateur enthusiasts. This reflects the simplicity of construction, light weight, lower costs both to construct and operate, and ease of maintenance.
Many designs are possible but the one that has proved its viability over all others is that which employs a fan with horizontal shaft and forward facing intake mounted towards the rear of the craft. The airflow produced by the lower section of the fan is employed for lift, a horizontal splitter plate being used to separate the lift air flow from the thrust air flow. The lift air is ducted through the hull and fed underneath the craft to be retained by a skirt.