hydrofoil

hydrofoil, a type of craft beneath which planes or foils are fitted which lift the hull of the vessel clear of the water when travelling at high speed. Research in this field began in 1891 and trials took place on Lake Maggiore in 1906 with a craft designed by Enrico Forlanini, which was fitted with ladder-type foils, and reached a speed of 38 knots. Three years later the USA conducted successful experiments with submerged foils and in 1927 German engineers evolved what is known as a surface-piercing foil. In 1956 the first commercial hydrofoil went into operation between Sicily and Italy, and the following year the first passenger-carrying hydrofoil was launched in the Soviet Union.

Today there are basically two types of hydrofoil craft, those fitted with the ‘canard’-type foil in which 30% of the boat's weight is supported by the forward foil and 70% by the after foil, and the conventional type in which the weight distribution is reversed. With the former the boat rides clear of the water above the surface-piercing foils, whereas with the latter, though the hull is lifted clear of the water, the foils remain submerged, giving greater stability though not such high speed.

The naval use of hydrofoils has been pursued by a number of countries without any significant lasting results. However, their commercial use as ferries is quite widespread, particularly in Russia.