Invention Of Hovercraft

Legend has it that the Patent Office did not know whether to classify the hovercraft invented by Christopher Cockerell in 1955 as a boat or an aircraft, because it did not float on the water, but nor did it fly through the air.

Christopher Cockerell (England) was an electrical engineer who bought himself a boatyard in order to pursue a personal interest in boat-building.As a scientist, he was interested in increasing the speed and efficiency of boats by reducing the hydrodynamic drag (i.e. friction from the water) and he bagan to investigate the idea of using a cushion of air so that the boat was not in contact with the water at all.
One of Cockerell's early experiment was to put two tins inside each other (reputedly a coffee tin and a cat food tin), the larger with both ends removed. He used the nozzle of a vacuum cleaner (with the motor reversed) to blow air into the narrow gap between the walls of the two tins, and found that the pressure of the air coming out of the tins was three times greater than if the small tin was removed - a concept known as the 'annular jet'. Cockerell applied this principle to design a hovercraft, which had several annular jets around the base of the craft, pointing downwards and inwards to provide lift.

The first hovercraft was SRN1, built by Saunders-Roe, a British aircraft manufacturer who had previously built flying boats and therefore had maritime and aeronautical expertise. SRN1 was launched on 30 May 1959, and successfully underwent trials off Cowes, Isle of Wight, before making the first hovercraft crossing of the English Channel - aptly, the crossing was made on 25 July, the 50th Anniversary of Frenchman Louis Bleriot's historic first cross-Channel flight. However, there were limitations to Cockerell's design, which could only clear relatively small waves or obstacles despite a clever 'closed vortex' system. This problem was solved by the addition of a flexible skirt, an invention sometimes credited to Cockerell and sometimes to C.H. Latimer-Needham (England). The skirt worked by trapping the air cushion underneath the hovercraft, giving much greater clearance and doubling the payload for a given power output.

Source - The Book Of Inventions by Ian Harrison