Amphibious Vehicle - Hovercraft

Hovercraft

For certain applications wheeled and tracked amphibious vehicles are slowly being supplanted by air-cushioned landing craft in many modern militaries. An air-cushion vehicle (ACV) or hovercraft is designed for traveling over land or water supported by a cushion of slow moving, low-pressure air ejected downwards against the surface below it. In principle a hovercraft can travel over any sufficiently smooth surface, solid, liquid, mixed, or anything in between. Considering that hovercraft can be quite large, some riding on an air-cushion contained by skirts several meters tall, these can deal with a reasonable level of unevenness in the terrain, unfazed by obstacles 1 to 2 meters in height. On the other hand the smallest personal hovercraft—ACVs no bigger than a compact hatchback—are nimble enough to follow some rolling of the terrain just as easily.

One of the benefits of this type of amphibious craft is the possibility of making them large—the British-built SR-N4 Mk-3 Channel-crossing ferries were 56.4 m (185 ft) in length and 23.8 m (78 ft) wide. Other benefits of ACVs include their very high water speed (an SR-N4 Mk-1 could do 83 knots (95 mph or 154 km/h) and the fact that they can make the transition from land to water (or vice versa) at speed—contrary to most wheeled or tracked amphibians. Drawbacks are high fuel consumption and noise levels.

For military purposes, the hovercraft's ability to distribute its laden weight evenly across the surface below it makes it perfectly suited to the role of amphibious landing craft. The US Navy LCAC can take troops and materials (if necessary an M1 Abrams tank) from ship to shore and can access more than 70% of the world's coastline, as opposed to conventional landing craft, that have only about 17% of that coastline available to them for landing.