Rising above the waves to improve speed and comfort
The Italian inventor, Enrico Forlanini, is believed to have built the first hydrofoil boat in 1898. It had two sets of submerged foils, one forward and one aft, that behaved much like small airplane wings. At speed, the lift from the foils made the boat rise clear of the water by several inches. Modern versions have two main foils, one on each side forward of amid-ships, and a third tail foil centered aft.When she is flying on the foils alone, a boat is capable of greatly increased speed because there is no longer any friction drag on the hull. Alternatively, the reduction in friction means better fuel economy.When the boat is out of the water and the foils are traveling through the water near the surface, there is no rolling, pitching, or pounding from waves.Hydrofoil craft present complex problems in design and, therefore, are relatively expensive. The height above water of the raised hull also creates problems with inboard power, which must somehow be transferred to a submerged propeller.After Alexander Graham Bell saw Forlanini’s boat in action, he built a hydrofoil that set a world speed record of 70.85 mph (114.02 km/h) in 1919. Bell’s boat suffered from stability problems, however, and was eventually abandoned. Modern hydrofoil designs contend for world speed records under sail at speeds of 40 knots and more.

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