"Fair is foul and foul is fair; Hover through the fog and filthy air."
William Shakespeare, Macbeth
A hovercraft—also known as an Air Cushion Vehicle (ACV)—floats on a cushion of air, the air being pumped under it by a large dueled centrifugal fan. It is amphibious and can be driven across relatively flat land for loading purposes, and then across reasonably calm water. As the cushion of air greatly reduces drag, the craft can travel across water at high speed.
Sir Christopher Cockerell (1910-1999) designed the first commercial hovercraft, the Saunders Roe Nautical One (SRN1). He conceived the idea in 1953, but it was not until June 1959 that his three-man craft—traveling at about 29 miles (46 km) per hour—was first tested. Cockerell decided to pump air into a narrow tunnel around the circumference of the craft. The air then escaped towards the center, where it built up a high- pressure cushion that supported the weight of the craft, making it stand clear of the ground.
Today, large commercial hovercrafts can cross the English Channel in less than half an hour. Military forces use them as personnel and weapons carriers, whereas oil companies employ them to transport drilling equipment to inaccessible places. They can also travel across wetlands, reeds, and swamps with very little impact on the water life near the surface.
