Motorboat Racing, sport involving competition between craft powered usually by inboard or outboard internal combustion engines. Motorboat racing in the United States is supervised by the American Power Boat Association (APBA), which was founded in 1903. Racing categories within the APBA consist of the inboard, inboard endurance, professional outboard, stock outboard, unlimited, outboard performance craft, drag, modified outboard, offshore, and R/C model commissions. The international governing body is the Union of International Motorboating, with headquarters in Monaco.
In the United States racing craft are assigned to a wide variety of classes according to the hull form and the type and size of engine. The three types of racing boat are the runabout, the hydroplane, and the tunnel-boat. The runabout has a V-bottom or flat-bottom design similar to the design of common utility boats. When in motion, this boat pushes over (planing), or through (nonplaning), the water. The hydroplane has a flat or concave bottom and is fitted with small stabilizing protrusions similar to outriggers, called sponsons, near the front of the boat. As the hydroplane gains speed, it rises out of the water, supported by the sponsons and the aerodynamic lift created by the hull bottom. The hydroplane is a much faster boat than the runabout. The tunnel-boat has a flat bottom with a sponson running the length of each side of the hull, creating an air tunnel between them. As the tunnel-boat gains speed, it rises out of the water, first on the sponson bottoms and then, as speed increases, on the aerodynamic lift generated by the tunnel. The tunnel-boat is not as fast as the hydroplane, but it is more easily maneuvered, especially in rough water. Boats are raced only against other boats of their type.
All three types of boat may be propelled by inboard motors—that is, engines located within the hull; by outboard motors—that is, power plants attached to the stern of the boat; or by inboard engines with outboard drive, known as inboard-outboard (IO) or stern-drive engines.
Classes within the various racing categories are based on the number of cubic inches of air displaced by the working pistons of each motor. Piston displacement in outboard classes ranges from less than 7.5 cu in (123 cu cm) to 186 cu in (3048 cu cm). For competitive purposes a distinction is made between specially designed or altered racing engines that use methanol or other high-powered fuels and craft powered by so-called stock engines—that is, factory-produced outboard motors using ordinary gasoline. Piston displacement in inboard classes ranges from the 55-cu-in (901-cu-cm) hydroplane to the 1000-cu-in (16,387-cu-cm) twin-engine offshore tunnel-boat. An “Unlimited” class of hydroplanes comprises the fastest crafts; such boats may be powered by automotive, aircraft piston, or turbine engines. The minimum weight for these crafts varies from 3800 to 6000 lbs (1724 to
Races are held on lakes and rivers, usually over a closed course marked by buoys. The size and shape of the course vary according to the body of water on which the race takes place. Closed-course races range in distance from 3 to 10 mi (4.8 to 16 km). Speed tests also take the form of races run against the clock over a straight kilometer or measured-mile course. In addition, long-distance offshore races are held each year.
IMPORTANT RECORDS AND COMPETITIONS
The speeds attained by racing boats vary widely. The measured-mile record for propeller-driven, unlimited hydroplanes, set in 1962 by American boat Miss U.S.I, is 200.419 mph (322.534 km/h). The record for an outboard hydroplane, set in 1989 by American boat MACH Propeller Specialties, is 176.556 mph (284.132 km/h). The world waterspeed record, set in 1978 by Australian craft Spirit of Australia, is 319.63 mph (514.38 km/h).
Each year about 300 regattas, or competitions, are held in the United States under the auspices of the APBA. The most famous American race is the annual APBA Gold Cup competition, which dates from 1904; it is open to hydroplanes equipped with any type of inboard-mounted engines or turbine engines with hulls between 28 and 32 ft (8.5 and 9.75 m) in length. Other notable American races include the President's Cup, the Indiana Governor's Cup, and the Seafair Trophy. An international competition known as the Harmsworth Trophy race has been held at irregular intervals since 1903. Important races held elsewhere in the world include the Cowes-Torquay in England and the Viareggio-Bastia in Italy.