300MPH IN AN AEROPLANE COULD BE DESCRIBED AS QUITE MUNDANE. In a car, it's ludicrously fast. BUT IN A BOAT?

Everyone knows the story of Donald Campbell’s tragic crash on Coniston Water but few remember another all British attempt 15 years earlier. Now a new book reveals what really happened to John Cobb and his jet-powered Crusader

- Steve Holter

The fact that only one man has exceeded this speed, and lived, tells you all you need to know. Ken Warby set the world water speed record in 1978, peaking at 345mph and averaging 317.59mph, in a wooden boat hand built by Warby in his back garden.

Thirty-one years on, his record still stands unbroken, giving some idea of just how difficult and dangerous it is to attain high speeds on water. But in 1949, some 30 years before Warby’s record-breaking run and 18 years before Donald Campbell lost his life trying to break the same record in Bluebird K7, two other Englishmen were planning an equally daring assault on the record.

VERY BRITISH HEROES

John Cobb, a wealthy fur broker with almost no experience of fast boats, already held the land speed record of 394.2mph thanks to a revolutionary twin aero-engined car, the Railton Mobil Special, designed by engineering guru Reid Railton. Now Cobb wanted to capitalise on his success by following the same route as Henry Segrave and Malcolm Campbell before him and taking to the water. His aim was not just to break the world record, which then stood at 141.7mph, but to be the first man to top 200mph on water.

The water speed record is not something to be taken on lightly. Unlike high speeds in a car, on water, the surface is constantly changing. A high speed car fights mainly only aerodynamic drag, whereas a boat has two fronts to combat, aerodynamics and hydrodynamics, so Cobb would have to rely on the design genius of his old friend Reid Railton again.