The design of the jetfoil

The paper outlines the structural design and development as well as the requirements of a jetfoil in which the welded aluminum-alloy hull must be seaworthy in any possible sea conditions and the foil system and the controls must be able to raise the hull above the water level while assuring a safe stable comfortable travel. The strut and foil retraction system allows hull-borne operation in shallower water than does a fixed foil system. The propulsion system consists of two parallel and independent gas turbine/waterjet plants arranged with the turbine inlet facing aft, a speed reduction gearbox connected through a high-speed shaft to the turbine and a low-speed shaft to the waterjet pump; water is discharged at high pressure through nozzles in the hull step, driving the boat forward. Also discussed is the automatic control system for jetfoil directional and stability control, along with the jetfoil outfitting and furnishings. Classification and certification of the jetfoil to meet the requirements of regulatory bodies are highlighted.