Glossary

All boats must be on the course and running at the 1 minute mark on the Start Clock. If they are not on plane, they will not be allowed to take part in the race. Boats that leave the dock after the 1 minute mark has passed are disqualified

To qualify for a race and receive qualifying points, all boats must make timed laps faster than 130 MPH. Boats that do not exceed 130 MPH will still be allowed to race, but do not receive points for qualifying

Five minute mark prior to the 5-minute gun. All boats must be held at the dock until the 5-minute gun. The “5 to the 5” callout on the PA allows drivers to synchronize their watches to the Start Clock

Area under the boat aft of the rear end of the sponsons to the rear of the boat

The driver’s mask is attached to an air tank that supplies breathable air in case the drivers ends up under water. The air tank is fastened in the area behind the cockpit

Twelve cylinder WWII fighter engine used in the U-3. Runs two turbochargers with water injection and makes 2500-3000 horsepower

Anchors hold the course buoys to the bottom of the river or lake. The anchors are marked via GPS so divers can find them to attach the buoy lines. On some lakes with deep bottoms, lines from the anchors are attached to floats near the surface to which the buoys attach

Describes the lateral (side to side) angle of the bottom of the sponson as measured against baseline of the transom. Anhedral means that the outside of the sponson bottom is lower than the inside. This is the case on the left sponson, and it helps the sponson skip across the water during the turn. Generally set to 3-4 degrees

The APBA Gold Cup is the oldest motorsports trophy in the world, awarded since 1904. All winners get their name engraved on this perpetual trophy and it is the one race that every team strives the hardest to win. It also has different race rules, generally requiring four flights of heats

The width of the boat. All H1 Unlimited hydroplanes must be between 12′-0″ and 14′-6″ wide

Light source used during inspection of propellers after every run. Props are sprayed with Zyglo and viewed with a black light, which will highlight potential flaws in the metal

Aerodynamic panels on either side of the cockpit at the front of the tunnel. Both panels can be modified in length and design to adjust the amount of air trapped under the boat. Forms the beginning of the wing section

Large round housing around the fan blades at the rear of the turbine engine where the combustion takes place

Another term for the sponson and the panels that extend down the sides of the boat. Sponsons are generally molded with these side panels as one piece.

All drivers must undergo training in a actual capsule that is inverted in the water, usually in a pool, showing their proficiency at breathing and exiting the capsule

Formation of vapor bubbles within the water at low-pressure regions that occur in places where the water has been accelerated to high velocities. Especially damaging if it occurs around the propeller

The area formed by the tunnel that incorporates the air trap. Combined with the curved deck, forms the shape of a wing and contributes to overall lift. Also know as the wing section

The head referee in charge of all other referees. Issues or certifies all penalties. Conducts Driver’s Meetings

The driver’s office

The entrance buoy to Turn 2, where all boats must be in a lane and must stay in that lane through the start.

On a turbine engine, air is compressed prior to adding fuel for combustion. The T-55 L-7 has seven stage compressor section (a series of seven blades and vanes), while the T-53 L-13B has five stages

Connects the long shaft to the short shaft. Has bolts that attach to both shafts to prevent them from separating

Map that shows the layout of the course and all buoys that make it up. Will be distributed to teams during the Driver’s Meeting at the beginning of the race weekend and will be used by the teams for timing marks and to plot strategies

Boat designated to ferry crew members to a boat that has been damaged or in danger of sinking

Every team has crew members that are specialists in specific areas like the turbine engine and propellers, as well as general crew that can work on all systems on the boat. Most crew members have decades of experience in boat racing at all levels

Drivers can “cut the course” – go through the infield – to try and position themselves for a better starting position or to block another boat from getting a lane

Boat is making no forward progress

The process of reducing fuel flow rate automatically if the N2 RPM rises above 118%. Monitored and recorded by the data recorder and read by the Technical Referee. Penalized if defueling is not performed

Safety zones within the race course that contain rescue boats, judge boats or other course boats. Usually in the center and both ends of the course. If a driver enters a safety zone, it is an automatic disqualification. Also referred to as Safety Zone

Driver did not start the heat or race

All drivers and Crew Chiefs must attend a mandatory meeting where race officials will distribute course maps and any rule changes that govern the race. All questions regarding the course or race procedures will be answered in this meeting

We use a minimum of two drones during each race – one above each corner. The footage from the drones is transmitted live to our referees, allowing them to make calls based on the on-water action

Driver has been disqualified from the heat or race. Can be for technical violations, driving violations or DMZ violation

Boats that are placed in areas outside the start/finish line that will display flags signifying the condition of the course. Also called a Judge boat

Hydroplanes have multiple voltages: 12VDC for gauges and data recorders, 24VDC for turbine engine operation and 48VDC for the turbine engine starter motor

The area directly behind the cockpit that houses the engine, gearbox and oil tanks

On the turbocharged Allison V-1710 12 cylinder piston engine in the U-3, the exhaust is routed through exhaust manifolds to run a single forward-mounted turbocharger per bank of cylinders

On non-turbocharged V-12 piston engines, exhaust stacks are short pipes (either 1 or 2) attached to each cylinder that release the exhaust directly into the air. Now mainly seen on vintage Unlimiteds. Also known as exhaust pipes

Aerodynamic device that “spoils” the air flowing across the right sponson while turning. Cuts down on the lift formed by that airflow, reducing the chance the sponson will lift and contribute to a blowover

Last race of the weekend. Winner of the Final Heat is the winner of the event

White Flag: One minute to start of the race or lead boat has one lap remaining. Yellow Flag: Hazardous condition on the course. Blue Flag: Possible penalty. Green Flag: Race has started. Checkered Flag: Race is over. Black Flag: All boats must return to the dock. Red Flag: Race has been stopped

Heat groupings are generally referred to as “flights”, meaning Heat 1A and 1B are the first flight, Heat 2A and 2B are the second flight, etc.

An Unlimited hydroplane has multiple frames, or bulkheads forming the interior structure of the sponsons and the center section. These frames add strength to the assembly and are usually no more than 18″-24″ apart & run the length of the boat. All frames are mechanically fastened and glued in place

Rubber bladder that contains up to 60 gallons of Jet A for turbines or methanol for the Allison-powered U-3

Turbines are allowed a maximum fuel flow rate of 4.2 gallons per minute. This is recorded for later analysis by referees and exceeding it can result in DSQ. Piston engines are not limited in fuel flow rate

Turbine engines use nozzles to spray fuel into the burner can (combustion chamber). The nozzles atomize the fuel to allow it to burn efficiently. There are a total of 28 nozzles in the T-55 L-7 and 22 in the T-53 L-13B

Power from the turbine engine is routed through the gearbox to propeller. It is a one-speed box and most are fitted with four gears. The gear ratio can be changed to suit course conditions

All Unlimiteds are required to carry at least two GoPro cameras during each heat that record onboard video footage to be used for referee decisions as well as promotional purposes

The idle setting of the turbine engine with the helicopter on the ground (remember they are from the CH-47). If the driver lets off the throttle too quickly, they run the risk of the engine reverting to ground idle, which will almost always stall the boat and doom their race, as getting the engine back to full power will take longer than the 5 seconds they can stay below 80 MPH

Head And Neck System. Mandatory head and neck restraint that all drivers wear when driving

If a heat was stopped and if less than 50% of laps were not completed, the heat may be restarted. If the stoppage was caused by a boat, the boat that caused the heat stoppage is not eligible to take part in the restart and is not scored in the original heat

Because all boats cannot run at once, the race is broken up into heats: 1A, 1B, 2A, 2B etc., with the goal to make it to the Final Heat. Final Heat placement is based on points collected in earlier heats

When the boat loses “traction” at the rear end and pivots to the left around the skid fin. Also called a spin

If the driver does not turn on the igniters prior to engaging the fuel pump on a turbine engine, occasionally the engine will fill with raw fuel then ignite all at once, shooting flames from the back of the engine. This does no damage, but is spectacular to watch

Glue that is used in areas that require extreme bonding strength. Good for aluminum to aluminum bonding, or bonding of dissimilar metals, including aluminum to carbon fiber parts

After the Final Heat, the two top finishers will be held for inspection, which generally includes weighing the boat to guarantee minimum weight and reading of the data recorder to insure integrity of the data. No work is permitted until the boat is released from impound

The fuel used in turbine engines. The turbines can burn just about any diesel-based fluid, but Jet A is preferred

The area occupied by the Chief Referee, Video Referee, Timing & Scoring Personnel and others at the Start/Finish Line. Also known as the Scoring Tower

An extremely strong synthetic fiber used in bulletproof vests. Used in the manufacture of the Safety Capsule and RPBS (Rotor Burst Protection System)

The inside-most lane on the course, next to the inner course marker buoys. A boat must stay within 20 feet of the inside course marker buoys to be considered to be occupying Lane 1. If a driver is in Lane 1 at the scoreup buoy, he must stay in Lane 1 throughout the entirety of Turn 1 after the start

The driver that leads the race. Generally will make the course longer for trailing boats by moving to an outer lane, forcing trailing boats to run wider. He can establish his lane wherever he wants on the racecourse, provided he has overlap to have changed lanes in the first place. The driver must hold their chosen lane throughout the turn

Sling that attaches to four points on the boat to lift it into and out of the water. Each leg of the sling must be rated to hold 6,000 pounds

Shaft that is attached to the output of the gearbox and extends through bottom of the boat

Methyl Alcohol. Fuel used by the turbocharged Allison V-12 in the U-3

The minimum weight of T-55 turbine-powered boat is 6575 pounds. For T-53-powered boat it is 3800 pounds and for a piston-powered boat it is 5775 pounds. Many new boats will weigh under these minimums and will add ballast to come up to the minimum weight, added in areas that help handling. As a boat ages and requires structural repairs, they will usually gain weight due to the material added in the repairs

Turbines have a maximum rating for “N2” – the RPM of the “Power Turbine” wheel. By rule, this cannot exceed 110% of the maximum rated RPM for more than 5 seconds. N2 RPM is recorded for later analysis by referees and exceeding it can result in DSQ. All turbine boats have lights that flash in the cockpit to warn the driver when they are over the 110% limit

Non Destructive Testing. Propellers are inspected after every run for issues that may lead to failure of the prop. They are sprayed with Zyglo and viewed with a black light, which will highlight potential flaws in the metal

Angled surfaces on both sides of the boat. Can be referred to as the sponson non-trip or afterplane non-trip, depending on location

When a boat is skipping, or planing on the water. All boats must maintain a minimum of 80 MPH, so even if the boat is planing, it must be going at least 80 MPH in order to not be disqualified

Overlap is the minimum distance a leading boat must be ahead of a trailing boat to make a legal lane change. It is five boat lengths prior to the start or seven boat lengths after the start

Boats and drivers may incur penalties for a variety of things: driving infractions on the water or technical violations, and they can take the form of time penalties, lap penalties, points penalties or disqualification

After each heat, boats are awarded points based on their finishing position. Points totals for the heats determine who will make it into the Final Heat. Points accrue toward National Championship standings

Limited to 16″ diameter and 3 blades. Costs around $15,000 and is good for 100 minutes of running time before it becomes a ticking time bomb, ready to come apart and tear up the back of the boat

All drivers qualify prior to racing in heats. Points are awarded based on qualifying speeds. Qualifying does not determine heat assignments

H1 Unlimited races use the following format: Qualifying, Preliminary Heats and a Final Heat. All qualifying, heat races and Final Heat award points that contribute to the National Championships for drivers and teams

In aerodynamic environments, corners that are exposed to airflow need to be radiused so as not to separate airflow on the part. In hydrodynamic environments, radiused edges are to be avoided at all costs due to the dramatic increase in drag that radiused edges create when in contact with water

A high-strength steel, aluminum or composite beam that spans between rear portion of the sponsons and through the back of the safety cell

We have two types of referees: those who watch the action on the course and call penalties based on driver behavior and those who monitor technical data and call penalties once the data recorders are read

Our rescue teams include at least two certified scuba divers that can reach a driver if the boat flips and lands upside down. They are usually trained in medical techniques to insure they can assist the driver in case of medical distress

Large wall of water thrown up by the propeller. There are literally tons of water in the roostertail that can cause extensive damage to other boats that enter it

A welded bracket that locates the rudder away from the transom, allowing the rudder to be more effective by adding leverage

All facets of the race, the boats, the technical specs and other areas are covered in multiple rulebooks, available on the H1 Unlimited website

Reinforced shell that forms the cockpit. Made from welded chromoly tubing, carbon fiber, Kevlar and bulletproof Lexan windows. It is egg-shaped at the back to help prevent damage in case of a rearward entry into the water – this design was adopted after Dave Villwock’s accident in 1997 in Tri-Cities. Also called the Safety Cell

Turbine-engined teams must take great precautions to minimize the ingestion of salt water. Salt buildup will cause pre-ignition in turbine engines which can lead to total destruction of the engine. Salt water also produces the fastest speeds the boats can attain, due to the additional density of the water

The entrance buoy to Turn 2, where all boats must be in a lane and must stay in their lane through the start. Also called the Commitment Buoy

Seat belts are a six-point design with a quick release latch. Crew members are required to pull the belts tight as the driver cannot do it by himself, and when done correctly, drivers are strapped in so tightly it is sometimes difficult for them to breath

This is a tube that carries the long shaft as it extends through the bottom of the boat. It has a rubber seal to prevent water leakage

Shaft that connects to rear end of the long shaft and extends to the back of the boat. The propeller is attached to this shaft. Some teams prepare multiple short shafts with different propellers to allow quick changes – sometimes while at the dock

Large steel plate mounted to the left side of the boat that digs in the water during turns and allows the boat to corner rather than skip on the water. May be adjusted in multiple dimensions to change handling of the boat, but must be completely flat – there is no concavity allowed

A very high strength braced area inboard of the skid fin that ties into the center section and is designed to take the tremendous forces the skid fin is capable of generating without coming apart

On the left sponson transom (rear edge of the left sponson), a bracket extends that the skid fin is attached to with high strength bolts through the skid fin. The bracket is attached to with high strength bolts and glue to the sponson transom

Angle of the leading edge of the skid fin in relation to the center line of the boat. Can be adjusted in or out in tiny fractions of an inch, but will almost always be set exactly parallel to the centerline of the boat.

Large extension bolted to top of canopy that attaches to front of the cowling and is used during salt water races. Serves to keep saltwater out of the engine. Some teams include a moveable door at the opening of the snorkel to further prevent saltwater from entering

A canard that has a split in the middle, allowing both sides to have different angles of attack

The clock started by officials that counts down from 15:00 to 0:00, signifying the start of the race. Drivers synchronize their timers precisely to the Start Clock to allow them to make the best start possible

An imaginary line that extends between the two buoys that are anchored on either side of the starting area in front of the Judge’s Stand. Referees monitor the start with a video camera that allows them to determine if a boat has jumped the gun

If a boat stops on the course, the driver must signal to his radio man or turn on the strobe light on the canopy to signify he is OK. If this is not done, the heat will be stopped

All race courses are surveyed by professional surveyors to certify the course distance. Distances are determined at the inner buoy line

Model of ex-military turbine engine used in the U-440. Features a 5-stage compressor section and makes around 1700 horsepower

The uprights that hold the rear tail. Covered with a aerodynamic carbon fiber panels. Also known as fairings

The referee in charge of reading the data from the data recorders carried by each boat and issuing penalties based on that data

Boat designated to take over from a tow boat that will get the damaged or non-running Unlimited back to the dock

Rods that bolt to the skid fin and the non-trip skid fin brackets on the boat and are adjusted to insure constant tension so as not to loosen under race conditions

In order for a driver to make a good start, he must know how much time it takes to make it from one point on the course to another. Drivers will usually use practice time to go slowly around the course to gather timing marks – the time between certain buoys – which will allow them to time their starting procedure more precisely

A rookie driver must be the “Trailer Boat” – trail the field at the start for at least his first two races. Additionally, in a Final Heat, a trailer boat may be added, and is the boat that has the least amount of points. The trailer boat must not pass the start line less than 5 seconds after 0:00 on the Start Clock

Area under the boat between beginning at the tip of the sponsons that is contained by the vertical surfaces of the sponsons and continuing aft to the transom

Device that forces air under pressure into the engine. The U-3’s Allison V-1710 V-12 has two of them

When a boat’s skid fin loses its grip in the water. Can be due to water conditions or when the skid fin angle is set too shallow. If the boat unhooks, it may slide outward a lane or two before getting enough “grip” to continue the turn

The braces that support the tail feathers

Drivers have lights that flash as they hit limits for N2 speed, giving them a warning to back off the throttle so they do not exceed the N2 speed limit for too long

A method of injecting water/methanol mix into the turbocharger that allows higher boost pressure and/or less knock under load. Used on the U-3’s Allison V-1710 V-12

Due to the aerodynamics of the Unlimiteds, they cannot safely run during high winds. Generally, wind speeds above 12-15 MPH will force cancellation of the race

The area formed by the tunnel that incorporates the air trap. Combined with the curved deck, forms the shape of a wing and contributes to overall lift. Also know as the center section

Where all of our Live Stream video is available, as well as over 3,000 onboard and other videos