H1 Unlimited is an American Unlimited Hydroplane racing league that is sanctioned by the American Power Boat Association. Until 2009, the series was known as ABRA Unlimited Hydroplane, in turn renamed from APBA Unlimited Hydroplane in 2004. The H1 Unlimited season typically runs from July through September, consisting of five races. A hydroplane is a very specific type of motorboat used exclusively for racing. One of the unique characteristics about hydroplanes is that they only use the water they're on for propulsion and steering - when going at full speed they are primarily held aloft by a principle of fluid dynamics known as "planing," with only a tiny fraction of their hull actually touching the water.
History
The unlimited hydroplane racing series was founded in 1946 when the unlimited class of boats was allowed to compete following World War II and the subsequent availability of surplus aircraft engines. It had been disbanded in 1922 in favor of the newly introduced "Gold Cup Class." The world's first sanctioned unlimited hydroplane race was held in 1903 in Ireland at Queenstown, and was very modest by later race standards. That race was won by Dorothy Levitt, driving an boat, powered by a Napier engine, at an average speed of. The boats were initially restricted to engines of a maximum of, later increased to. Hulls with "steps" or "shingles" on the underside were prohibited. One reason for the rule change was to end the domination of its star driver, Gar Wood, who had won five consecutive Gold Cups from 1917. One win in 1920 in his twin Liberty L-12 powered Miss America, averaged in the race over an course and set a race record that stood until 1946. "King Gar" had entered fifteen Gold Cup heats during those pinnacle years. He finished first twelve times and second three times. Throughout the years, only two boats showed up to challenge Miss America; one of those was piloted by George Wood, Gar's younger brother, in Miss Chicago. Another reason for the rule change was to make racing more affordable. In 1929, the Class was introduced by the MississippiValley Power Boat Association. The majority of these boats were powered by Hispano-Suiza 8 aircraft engines or Curtiss OX-5s. These boats were popular in the Southern and Midwestern US, but did not attract the media attention that the expensive and exotic-looking Gold Cup Class counterparts had. In 1946 after the hiatus due to the war, the MVPBA was absorbed into the APBA, and as a result the 725s and the Gold Cups merged to become the APBA Unlimited Class. The turbine engine was first used in competition by the U-95 "Whiz-per" in 1974, which sank that August at Seattle. The next entrant with turbine power was the Pay 'n Pak in 1980 on the Columbia River at Tri-Cities, but it flipped 2½ times in a test run prior to the Sunday heats. It was the sole turbine again the following year, but through the 1980s, the turbine gradually displaced piston power.
Today
The H1 Unlimited class is sanctioned by APBA, its governing body in North America and UIM, its international body. Unlimited Hydroplanes are fast boats capable of more than on the straights and running average lap speeds of. They are in length and weigh a minimum of. The modern turbine-powered unlimited hydroplane is derived from the 3-point prop-riding hydroplanes of the 1950s. These were the first boats to ride on a cushion of air trapped between "sponsons" mounted on the sides of the front of the boat, and the bottom half of the propeller, which were all that touched the water. They were called "Unlimited" because they were the only class of boat racing the APBA that had no restrictions on the displacement size of their piston engines. The designation Unlimited has stayed with the class in the turbine era, even though there are restrictions on the turbine engine and its fuel. The Lycoming T55 L7C, originally used in Chinook helicopters, is the only turbine engine currently allowed in the sport.
