An area between and behind the sponsons which traps the
air cushion on which the hydro rests at speed.
Allison A standard Unlimited powerplant, used in American World War
II fighter aircraft.
APBA The American Power Boat Association, the governing body of all
competitive hydroplane classes.
Apex of the turn The route that a hydro driver tries to take through
the turn without adjusting direction.
Back-off point The point where a driver lifts his foot off the
throttle in preparation for the turn.
Blower Another name for a supercharger.
Bonus points Given to the fastest boats in a race, a practice used
in the 50s and which has since been discarded.
Bow The front of the boat.
Buoy line The line made by the buoys when they are set in a row.
Cab-over A hydro design where the driver sits in front of the engine
and which shifts the center of gravity toward the stern.
Checkered flag Waved at the end of the heat to signify the boat has
Chevy Mercruiser An engine tried in a hydroplane.
Choppy water The best for hydro racing, small pointed waves.
Chrysler Hemi The auto engine used in most auto powered hydros.
Chute The straightaway.
Cockpit The area where the driver sits in the hydro.
Contestants meeting Usually held on Wednesday before the race, to
discuss rules and signals.
Contra-rotating props Two props that rotate in opposite directions.
Conventional transom Thick and narrow boat stern.
Course judge He watches for rule violations on the course.
Cowling The shell which surrounds the engine and the cockpit.
Crew chief The head man in the pit crew.
Dead-in-the-water When a boat comes to a stop on the course.
Dicing The maneuvering before the start of the race.
Dove-tail A type of tail fin, looks like no tail fin at all but uses
a small spoiler at the stern of the cowling.
Driver The person who sits in a hydro and drives it.
Drivers meeting Held the day before the race, discussions of
Drivers Qualification Committee A group that determines which
drivers are qualified to handle a hydroplane.
Driving suit The garment the driver wears, made of fireproof
Dry sponson A sponson in which water cannot enter.
Dye-checking Part of the safety precautions, the testing of the
props, rudders, etc. for signs of fatigue.
Exit pin The last buoy in the turn, the beginning of the chute.
Fan plan A type of race whereby the winner of the final heat is the
winner of the race.
Five-minute gun Fired five minutes before the starting gun.
Flares Set off when an emergency occurs and the race must be
Fluke The blade of the propeller.
Fork-lift The bow where the sponsons extend beyond the hull on
Four-point design The standard step hydro, in prominence before the
evolution of the three-point design.
Gold Cup The Stanley Cup of unlimited hydroplanes.
Green flag One lap to go before the finish.
Griffon A model of Rolls-Royce engines used a little in hydros.
Groove The route the boat takes through the turn.
Guns Fired at five minutes before the start, one minute before the
start, at the start and at the finish.
Hallet drop sponsons The deck of the sponsons are below the level of
the hull's deck.
Heat One 6-lap event on a 2½-mile course or 5 laps on a 3-mile
Hooker He who uses another boat to time his start.
Horizontal stabilizer The plane that lies across the top of the tail
which resembles the wing of an airplane.
Hull Balance Very important. Determines the boat's ride.
Hydromaniac One who lives, eats and sleeps hydroplanes.
Hydroplane A boat that skims over the surface of the water.
Inboard sponson The sponson that faces to the inside, left one.
Infield That area around which the buoys are located.
Instrument panel The plate where the dials and knobs are located for
use by the driver.
Jumped the gun Passed across the starting line 30 seconds or less
before the starting gun fired. One lap penalty.
Kite When the bow begins to rise into the air dangerous.
Lap One tour around the race course.
Laughing gas Squirted into the engine for a quick burst of speed.
Life support decelerator Helps to slow down the driver as he flies
through the air after being thrown from the boat.
Lifejacket Worn by the drivers to let them float when thrown from
Limiteds Numerous classes of racing boats that are governed by
Lizards The affectionate name for girls who hang around in the hydro
Low profile transom Wide and thin boat stern.
Merlin A Rolls-Royce model engine used extensively in unlimiteds.
Messerschmitt A German fighter plane engine tried in unlimiteds but
National High Point Standings The standard which determines the
Nitrous Oxide or Nitrous Laughing gas.
Non-trip Lets the rear portion of the hydro slide sideways.
Non-trip chine A beveled edge on the inboard sponson.
Nosing down When the bow goes into the water.
Number one lane Closest to the buoy line.
Official barge The area where the referee and scorers work.
On the step When the boat rises to sit on its plane.
One-minute gun Fired one minute before the start of the race, all
boats must be on the course and running at this time.
One-point design Tried by a designer in 1957 but did not work.
Packard Engine tried in unlimiteds without success.
Pickle-fork The same as the fork-lift bow basically.
Pit crew Those men who work on the boat.
Pit pass Allows the holder to enter the pits.
Pitching effect The tendency to tilt sideways in a turn.
Pits The area in which the boats rest when not racing.
Planing Skimming on the water's surface.
Porpoise When the boat rises and drops drastically, or bounces.
Promoter The group that sponsors the race.
Prop The device that propels the boat.
Prop pitch The angle of the prop's flukes.
Propeller Magazine The publication of the APBA.
Prop-riding The prop is only halfway in the water.
Prop-torque The effect of prop-riding, a constant left turn.
Qualification ladder The order in which boats may make qualifying
Qualify Turn laps at 95 m.p.h. on a 2½-mile course or 100 m.p.h. on
a 3 mile course.
Quill shaft A thin rod that connects the blower to the power unit,
the cause of many breakdowns in the past.
Race committee The organization that operates the race.
Racing trim As it is when it races.
Referee The absolute authority on all matters concerning the rules
and running of the race, the APBA supervisor.
Rolls Engines made by Rolls-Royce, usually means the Merlin.
Roostertail The high plume of water behind a hydro at speed.
Rudder The device that causes the boat to turn.
Safety belt Not allowed in an unlimited hydroplane.
Sanction The right to hold a race.
Sandbagging Purposely going slow for one reason or another.
Shutdown to decelerate.
Shutdown buoy Same as the back-off point, usually.
Signals Communication between the boat and the barge.
Skid fin A blade that holds the boat through the apex of the turn.
Spilling air Letting the air cushion go to get better control,
especially in the turn.
Spoiler Any device that disrupts the flow of air.
Sponson On each side of the hull toward the bow, the members that
resemble pontoons and on which the boat rides.
Sponsor The business or person who helps pay for the boat's
Stack The exhaust pipe.
Stack fire A fire on the exhaust pipes.
Standard bow The rounded nose.
Starting clock A black-out clock that tells the time before the
start of the race.
Starting gun Fired at the beginning of the race.
Starting line Opposite the official barge, where the boats start.
Steering wheel Used by the driver to turn the boat.
Step hydro Used many years ago, same as the four-point design.
Stern The rear of the boat.
Sticky water Smooth water which saps power from the engine and does
not allow enough air in the air trap.
Tail fin At the stern of the boat to stop it from bouncing from side
Tandem-mount Engines placed one in front of the other.
Tenders Small boats that do various duties on the race course.
Three-point suspension The basic design of hydros today, the boat
rides on three points.
Throttle Causes the engine's speed to alter.
Thunderboat A metaphor denoting Unlimited Hydroplanes.
Top speed The fastest speed obtained on the chute.
Trailer The device that carries the boat on land.
Transom The flat surface of the stern.
Trim-tab A spoiler located on the tail fin to offset prop-torque.
Turbine A type of engine, roughly the same as a jet engine.
Turbo Short for turbocharger.
Turbocharger Performs the same job as a supercharger but uses power
from the exhaust.
Turn buoy Where the driver begins his turn.
Unlimited A class of hydroplane not limited in engine size.
Unlimited Racing Commission The body that awards sanctions and
recommends rule changes for Unlimiteds.
Walk When the boat hops from sponson to sponson.
Walk the stern A slight turning of the boat before the rudder is
moved, in perparation for the corner.
Warm-up speed The speed ideal for warming up the engine before the
Washed down When a boat is caught in another's roostertail and the
engine quits as a result.
Water condition Whether the water is choppy, sticky or rough.
Waterline length The distance between the tip of the bow to the tip
Wet sponson A sponson in which water is allowed to enter.
Wheel A propeller.
White flag Signifies the period between the one-minute gun and the
Yellow flag Signifies the period between the five-minute gun and the
one-minute gun and when there is a hazardous condition on the race course.
- Air Trap
(Reprinted from Roostertails Unlimited by Andy Muntz, 1973)
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page was last revised Thursday, April 01, 2010
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© Leslie Field, 2000