Hydroplane Boats
The basic hull design of most hydroplanes
has remained relatively unchanged since the 1950s: two sponsons in front,
one on either side of the bow; behind the wide bow, is a narrower, mostly
rectangular section housing the driver, engine, and steering equipment.
The hydroplane is a very specific type of
motorboat used exclusively for racing. One of the unique things 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.
The aft part of the vessel is supported in the water by the lower half
of the propeller, which is designed to operate semi-submerged at all
times. The goal is to keep as little of the boat in contact with the
water as possible, as water is much denser than air, and so exerts more
drag on the vehicle than air does. Essentially the boat 'flies' over
the surface of the water rather than actually traveling through it.
One of the few significant
attempts at a radically different design since the three-point prop
riding design was introduced was referred to as Canard. It reversed
the width properties, having a very narrow bow that only touched the
water in one place, and two small outrigger sponsons in the back.
Early hydroplanes had mostly
straight lines and flat surfaces aside from the uniformly curved bow
and sponsons. The curved bow was eventually replaced by what is known
as a pickle fork bow, where a space is left between the front few feet
of the sponsons. Also, the centered single, vertical tail (similar to
the ones on most modern airplanes) was gradually replaced by a horizontal
stabilizer supported by vertical tails on either side of the boat and
as of 2006 the horizontal stabilizer was mostly abandoned. Later, as
fine-tuning the aerodynamics became more important, the bottoms of the
main hull have subtle curves to give the best lift.
Unlimited hydroplane engines
the aviation industry has been the main source of engines for the boats.
For the first few decades after World War II, they used surplus World
War II-era internal-combustion airplane engines, typically Rolls-Royce
Merlins or Griffons, or Allison V-1710s, all liquid-cooled V-12s. The
loud roar of these engines earned hydroplanes the nickname thunderboats.
The "limited" classes of
inboard hydroplane racing are organized under the name Inboard Powerboat
Circuit. These classes utilize automotive power, as well as two-stroke
power. There are races throughout the country from April to October.
Many Unlimited drivers got their start in the "limited" classes.
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