Jetsprint orsprint boat racing[1] is a form ofmotorboat racing in whichjetboats, with a crew of two, race individually against the clock through a twisting series of channels in less than a metre of water.[2]
Tracks are typically designed for spectators, and racing is fast and loud, with boat motors usually powered byV8s developing well over 500 hp.[3]
Jetsprinting as an organised sport originated inNew Zealand in 1981 by Pat Quinn and his wife, Margaret.[4] Margaret spectated jet boat Marathons which Pat competed in, but wanted to see more of the race, suggesting a smaller, more condensed track. Events were originally held in the same naturalbraided rivers that had inspiredSir William Hamilton to develop thejetboat, but when the sport was introduced toAustralia in the mid-1980s, permanent artificial courses were used—and this is now the norm even in New Zealand.
There is now a world championship under the auspices of theUnion Internationale Motonautique,[5] with hosting rotating between New Zealand, Australia and the U.S.A.
The race itself consists of a predefined course through the channels with 25 to 30 changes of direction. These races generally take just 45–60 seconds. Once qualifying is completed, the competitors each run the course with the fastest qualifiers running last. The fastest 16 (typically depending on the number of competitions) proceed to the next round. This is then reduced to the top 12, Top 8 then the top 5 and finally the fastest three.
A jetsprint hull is typically short - just 3.8 to 4.0 metres (12½ to 13 feet) long. The hull's vee is usually 23 to 25 degrees with severalstrakes on each side. A short hull is preferred, as a longer hull takes more distance to turn and usually must be turned at a slower speed. The strakes provide "traction' by stopping the boat from sliding sideways across the water when turning at high speed.
Arollcage must be fitted to the boat.
A crew consists of the driver and a navigator, whose responsibility is to guide the driver through the course - typically via simple hand signals, pointing the hand in the direction that the boat must go at the next intersection.
There are two internationally recognised classes
Group A - engines in Group A boats are restricted to either 6.7-litre (412 cubic inch) engines withcast iron blocks and heads, or 6-litre (365 cubic inch) engines with aluminium heads. Both engines are only allowed two push-rod operated valves per cylinder. Furthermore, the engine must be normally aspirated, using a four-barrel carburetor. Fuel is 100+ octaneaviation fuel. Typically these engines produce up to 650 horsepower
Super Boats - engines in the Super Boat class have no maximum size, but instead have a minimum size restriction. Normally aspirated engines must have a displacement of 6.5 litres (400 cubic inches), while forced induction (turbocharged or supercharged) engines must be at least 3.8 liters (235 cubic inches) in displacement. These engines typically are fuel injected and runmethanol fuel. The small-block engines typically produce 950+ horsepower, while the big blocks can produce between 1000 and 1600 horsepower.
Nitromethane andnitrous oxide are not allowed.
[...] Sprint Boat racing, or Jet Sprinting as it's known in its founding country of New Zealand [...]
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