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H1 Unlimited

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H1 Unlimited

H1 Unlimited
Category Unlimited hydroplane racing
Country  United States
Inaugural season 1946
Drivers 12
Teams 12
Engine suppliers Lycoming Engines
Drivers' champion Jimmy Shane
Teams' champion Miss Madison (U-6)
Official website .com.h1unlimitedwww
Current season

H1 Unlimited is an American Unlimited Hydroplane racing league that is sanctioned by the American Power Boat Association (APBA). 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 (or hydro, or thunderboat) 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 (not for flotation) - 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.


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".[1]

The world's first sanctioned unlimited hydroplane race was held in 1903 at Queenstown, Ireland and was very modest by later race standards. That race was won by Dorothy Levitt, driving a 11 metres (35 ft) boat powered by a 56 kilowatts (75 hp) Napier engine, totaling an average speed of 31.43 km/h (19.53 mph).[2]

The boats were initially restricted to engines of a maximum of 10,240 cm3 (625 cu in), later increased to 12,000 cm3 (732 cu in). Hulls with "steps" or "shingles" on the underside were prohibited.[1]

One reason for the rule change was to end the domination of its star driver, [1]

In 1929, the 725 cu in (11,880 cm3) 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.[3]

In 1946 after the hiatus due to the war, the MVPBA was absorbed into the APBA,[4] and as a result the 725s and the Gold Cups merged to become the APBA Unlimited Class.[3]


The H1 Unlimited (prior to the 2009 Oryx Cup, known as ABRA Unlimited (American Boat Racing Association) since 2004[5]) 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 320 km/h (200 mph) on the straightaways and running average lap speeds of 209–266 km/h (130–165 mph). They are 8.5–9.1 metres (28–30 ft) in length and weigh a minimum of 3,060 kilograms (6,750 lb).

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 not the only turbine engine currently allowed in the sport.[6]

Past National High Point Champions

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