Obituary: Sir Christopher Cockerell

THE THEORY behind one of the most successful inventions of the 20th century, the hovercraft, was originally tested in 1955 using an empty Kitekat cat food tin inside a coffee tin, an industrial air blower and a pair of kitchen scales.

Christopher Cockerell was initially testing out the idea that it was possible to produce a cushion of air between the bottom of the tins and the surface of the scales. Once he had established that this was possible he decided to experiment with more sophisticated models. Although his first tests were carried out on dry land his main aim was to prove that drag or friction between boats and water could be substantially reduced if the "craft" floated on an air cushion. And so the "hovercraft" came into being. Indeed Cockerell came up with the word too, which was recently chosen to represent 1959 in the 100 words which encapsulate the 20th century for the millennium edition of the Collins English Dictionary.

Christopher Sydney Cockerell was born in 1910 at Cherry Hinton near Cambridge, the son of Sir Sydney Carlyle Cockerell, sometime private secretary to William Morris and from 1908 to 1937 Director of the Fitzwilliam Museum, Cambridge. The Cockerells were a talented family. The sons of Sydney John Cockerell, a London coal merchant, and Alice nee Bennett, the daughter of a City watchmaker, Sir Sydney's elder brother, Theodore, was a biologist, his younger brother, Douglas, an eminent bookbinder; while Douglas's son Sydney Maurice ("Sandy"), two years Christopher's senior and also a bookbinder, was a celebrated and innovative designer of marbled papers.

Despite an interest in the arts, Christopher read Engineering at Peterhouse, Cambridge. After Cambridge he worked for the Radio Research company until 1935 and then for the Marconi Wireless Telegraph company from 1935 until 1951.

He had an enormous capacity for invention and his father, despite reservations (he once described his son as "no better than a garage hand"), put up the money for his early patents. (When Sir Sydney died in 1962, aged 94, some obituaries of this great museum director and manuscript collector, friend of Bernard Shaw and T.E. Lawrence, literary executor of Thomas Hardy, called him simply "grandfather of the hovercraft".)

During the war years Cockerell worked with an elite team at Marconi to develop radar, a development which Churchill believed had a significant effect on the outcome of the Second World War, and Cockerell believed to be one of his greatest achievements. Whilst at Marconi Cockerell patented 36 of his ideas.

Cockerell left Marconi in 1950, and with a legacy left by his beloved wife Margaret's father, he and Margaret were able to purchase a small boatyard in Norfolk. This never seemed to make money and Cockerell's mind turned back to earlier ideas.

He decided to use larger models on water. Initial experiments convinced Cockerell that boats could be made to float on a cushion of air, thus reducing the effect of the water drag. After many trials he successfully designed a craft which proved his ideas were correct. He was not surprised. The modified punt he used had a special pump to blow high pressure air down under and around the rim of the craft. A strong rubber curtain regained most of the air, hence creating lift.

Cockerell had set up a company, Ripplecraft, to develop his ideas further and in 1955 he eventually convinced the Ministry of Supply to back his project. He had a hard time trying to convince the military: the Admiralty said it was a plane not a boat; the RAF said it was a boat not a plane; and the Army were "plain not interested". The irony is that it has been the Marines who have taken the hovercraft most seriously, with over 100 giant craft now in use in America and 250 in the Soviet Union, many used in recent conflicts.

In these early days Cockerell's idea was patented and immediately put on the secret list. Nothing happened and Cockerell became increasingly agitated. Eventually, in 1958, after declassification, the National Research Development Council (NRDC) funded the design and construction of SRN1 - the world's first man-carrying amphibious hovercraft.

Saunders Roe, the flying boat firm at Cowes on the Isle of Wight, were given the contract, and the firm, under Cockerell's guidance, worked avidly on the 20ft craft dubbed the "flying saucer".

Ahead of schedule, on 31 May 1959, the seven-ton craft flew, only eight months after the commencement of design work. But it was not until 11 June that she made her first public appearance in front of the world's press. Such was the interest in this new form of transport the press refused to leave until she was demonstrated in the water.

Within weeks, on 25 July she made a crossing of the English Channel, from Calais to Dover, with Cockerell aboard as human ballast, on the 50th anniversary of the first aeroplane crossing of the Channel. Cockerell's dream had become a reality. Since then hovercraft have carried over 80 million people and 12 million cars across the Channel and have been in continuous service for over 30 years.

Besides hovercraft he is attributed with the invention of wave power in the 1970s, hovertrains, and sidewall hovercraft (catamarans). Although Cockerell disagreed with the way the NRDC proceeded with hovercraft production, and in 1966 resigned from the board of Hovercraft Development, today hovercraft are enjoying a renaissance. Cheaper, quieter diesel engines, new construction materials and advanced skirt design mean that a hovercraft today is the same price as one 30 years ago. With developing countries having the greatest need for hovercraft, with shallows, coral reefs, mud flats, no ports and unprepared beaches, hovercraft are coming into their own.

Last weekend the hovercraft industry launched Hovershow '99 - the biggest show since 1966. Visitors were impressed by how the hovercraft has become a viable and versatile workboat and export sales in the last year have reached pounds 20m. Recent sales have been to Canada for coastguards, to Lithuania as crew boats, to Hong Kong for fishery patrols, to Nigeria for oil crew boats, to Finland for coastguards to be used on ice; and to Sri Lanka for military purposes. As Cockerell said, "Hovercraft will always be around - you can't uninvent something!"

During the course of the weekend, the 40th anniversary of the first flight of the hovercraft was celebrated, and Cockerell sent his best wishes but was too frail to attend. On Monday a flypast was staged in his honour. He died the following day, with as many patents to his name as he had years.

Christopher Sydney Cockerell, designer and inventor: born Cherry Hinton, Cambridgeshire 4 June 1910; research and development, Marconi Wireless Telegraph Co 1935-51; consultant on hovercraft to the Ministry of Supply 1957-58; consultant, Hovercraft Development Ltd 1958-70, director 1959- 66; chairman, Ripplecraft Co Ltd 1950-79; CBE 1966; FRS 1967; Kt 1969; consultant, British Hovercraft Corporation 1973-79; founder and chairman, Wavepower Ltd 1974-82, consultant 1982-88; Foundation President, International Air Cushion Engineering Society 1969-71, Vice-President 1971-99; President, UK Hovercraft Society 1972-99; RDI 1987; married 1937 Margaret Belsham (died 1996; two daughters); died Sutton Scotney, Hampshire 1 June 1999.