
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 11-meter (35 ft) boat, powered by a 56-kilowatt (75 hp) Napier engine, at an average speed of 31.4 km/h (19.5 mph).
The boats were initially restricted to engines of a maximum of 10.24 liters (625 cu in), later increased to 12.00 liters (732 cu in). 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 113.317 km/h (70.412 mph) in the 48 km (30 mi) race over an 8 km (5 mi) 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 Benton Wood, Gar's younger brother, in Miss Chicago. Another reason for the rule change was to make racing more affordable.
In 1929, the 725 cu in (11.88 L) Class was introduced by the Mississippi Valley Power Boat Association (MVPBA). 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.
Following the protest-ridden 1956 APBA Gold Cup at Detroit, which took 85 days to settle, the Unlimited Class severed all but nominal ties with the APBA. In 1957, the Unlimited Racing Commission (URC) was formed. In the 1990s, the URC was renamed the Unlimited Hydroplane Racing Association (UHRA). In 2001, HYDRO-PROP, Inc., bought the licensing rights to the Unlimited Class from the APBA and managed the unlimited class through the 2004 racing season. The American Boat Racing Association (ABRA) was formed in 2005 and was renamed H1 Unlimited in 2009.
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,[12][13] but through the 1980s, the turbine gradually displaced piston power.