Hydroplane (boat)

A hydroplane (or hydro, or thunderboat) is a fast motorboat, where the hull shape is such that at speed, the weight of the boat is supported by planing forces, rather than simple buoyancy.

That day the No-Vac set the world water speed record for an outboard powered boat of 78 miles per hour (126 km/h).

The aft part of the vessel is supported in the water by the lower half of the propeller, which is designed to operate semi-submerged at all times.

It reversed the width properties, having a very narrow bow that only touched the water in one place, and two small outrigger sponsons in the back.

Later, as fine-tuning the hydrodynamics became more important, the bottoms of the main hull have subtle curves to give the best lift.

Donald Campbell set seven world water speed records between 1955 and 1964 in the jet engine hydroplane, Bluebird.

Prior to 1977, every official water speed record had been set by an American, Briton, Irishman or Canadian.

On November 20, Australian Ken Warby piloted his Spirit of Australia purely on the jet thrust of its Westinghouse J34 turbojet to a velocity of 464.5 km/h (288.6 mph) to beat Lee Taylor's record.

Warby, who had built the craft in his back yard, used the publicity to find sponsorship to pay for improvements to the Spirit.