The idea of riding on air dates to 1716, when Emanuel Swedenborg sketched a hovering craft powered by hand pumped air. In 1915 Austrian engineer Dagobert Müller built a working air cushion torpedo boat for the Austro-Hungarian Navy that topped 32 knots in the Adriatic, yet it was scrapped for lack of interest. In the 1950s Ford’s Levapad concept cars hovered a fraction of an inch up and failed on any imperfect road. British engineer Christopher Cockerell solved the problem with a coffee can, a cat food tin, kitchen scales, and a hairdryer, discovering the momentum curtain: a ring of fast downward air that traps a high pressure cushion and needs a quarter to half the power a helicopter would use for the same lift.

The military services each claimed his invention belonged to the others, but the SR.N1 crossed the English Channel in 1959, and Prince Philip crashed it into a wave, leaving the Royal Dent. With only nine inches of clearance it needed Cecil Latimer-Needham and Denys Bliss’s flexible skirt, whose rubber fingers bend over obstacles and snap back. Cross channel giants followed: the SR.N4 Mountbatten class carried up to 418 passengers and 60 cars, and the French N500 Naviplane matched it, both cruising over 80 knots. The 1973 oil crisis, cheaper wave piercing catamarans, and the Channel Tunnel ended the ferries by 2000, but hovercraft found new roles.

• The US Navy’s LCACs carry troops and vehicles straight from ship to beach.
• Russia’s Zubr class, the largest military hovercraft, carries three main battle tanks and 140 troops.
• Finland’s coast guard uses hovercraft for rescues on breaking spring ice.
• UK hauliers floated 300 ton transformers over weak bridges on air cushions to spread the weight.
• A hover barge dragged a 330 ton drilling rig across the swamps of Suriname.