The ability of hovercraft to cross dry land as well as water has seen them employed in the military and tourism sectors for many years. Although once billed as the next generation of transportation, they have somewhat decreased in popularity over the last decade. Despite this, their usefulness is still readily apparent.
The core principle of a hovercraft is that the hull of the vehicle is suspended on top of a giant cushion of air, held in place by ﬂexible rubber that allows it to traverse difﬁcult terrain or choppy waves without being torn apart. At the centre of a hovercraft is a huge fan that ﬁ res air downwards, pushing the hull off the ground as high as two metres (6.5 feet). Smaller fans on top of the hull push air backwards, giving the hovercraft forward momentum. Rudders direct this ﬂ ow of horizontal air to allow a hovercraft to change its direction.
Traditional hovercraft have an entirely rubber base that allows for travel on land or sea, but others have rigid sides that, while suited only to water, can have propellers or water-jet engines attached for a quieter craft.