![Air Chair 01](https://upload.wikimedia.org/wikipedia/commons/a/a8/Air_Chair_01.jpg)
The sit-down
hydrofoil
A hydrofoil is a lifting surface, or foil, that operates in water. They are similar in appearance and purpose to aerofoils used by aeroplanes. Boats that use hydrofoil technology are also simply termed hydrofoils. As a hydrofoil craft gains sp ...
, first developed in the late 1980s, is a variation on
water skiing
Water skiing (also waterskiing or water-skiing) is a surface water sport in which an individual is pulled behind a boat or a cable ski installation over a body of water, skimming the surface on two skis or one ski. The sport requires suffic ...
, a popular
water sport
Water sports or aquatic sports are sport activities conducted on waterbodies, and can be categorized according to the degree of immersion by the participants.
On the water
* Boat racing, the use of powerboats to participate in races
* Boatin ...
. When towed at speed, by a powerful boat or some other device, the board of the hydrofoil 'flies' above the water surface and generally avoids contact with it, so the ride is largely unaffected by the wake or chop of the water and is relatively smooth. The air board is a modified hydrofoil where the skier stands up.
History
Hydrofoil
A hydrofoil is a lifting surface, or foil, that operates in water. They are similar in appearance and purpose to aerofoils used by aeroplanes. Boats that use hydrofoil technology are also simply termed hydrofoils. As a hydrofoil craft gains sp ...
s date back the early 1900s, however they were not part of a recreational sport. While the first hydrofoil boat was created in 1906 by Italian inventor
Enrico Forlanini
Enrico Forlanini (13 December 1848 – 9 October 1930) was an Italian engineer, inventor and aeronautical pioneer, known for his works on helicopters, aeroplanes, hydrofoils and dirigibles. He was born in Milan. His older brother Carlo Forlanin ...
, the first
waterski
Water skiing (also waterskiing or water-skiing) is a surface water sport in which an individual is pulled behind a boat or a cable ski installation over a body of water, skimming the surface on two skis or one ski. The sport requires suffic ...
hydrofoil was invented in the early 1960s by Walter Woodward, an aeronautical engineer, with two skis attached to a bi-wing hydrofoil.
In 1972, Mike Murphy and Bob Woolley added a bi-wing hydrofoil to a surfing
kneeboard
A kneeboard is a board ridden in a kneeling stance. Kneeboards are ridden in ocean surf, or while being towed behind a boat on a lake or river.
Background
Kneeboard riders generally wear life jackets or wet suits and catch the wave by paddling a ...
, then reduced the bi-wing to a single wing.
Murphy and Bob Woolley then applied the concept to sit-down hydrofoil, with Woolley riding the first "Sit Ski" in 1984.
After various material changes, including the addition of a seat belt to keep rider and ride together and prevent separation collisions, they sold their first "Air Chair" in 1990.
Advancements in materials and hydrofoil design have created stronger rigs, gentler rides (shock absorbers in the seat), more maneuverability, and boards that combine sit-down and stand-up (air board) for
surfing
Surfing is a surface water sport in which an individual, a surfer (or two in tandem surfing), uses a board to ride on the forward section, or face, of a moving wave of water, which usually carries the surfer towards the shore. Waves suitabl ...
.
Sit-down hydrofoil components
*Seat (also referred to as the tower) - located directly above the hydrofoil and commonly made of
aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
. The seat comes with a seat belt to keep rider and ride together.
*Board - a molded ski typically made of a
fiberglass
Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...
or
carbon fiber
Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon compo ...
resin.
The board has two bindings connecting it to the rider's feet to allow for better control the hydrofoil.
*Foil assembly - a long strut, usually around 3 feet long, connected to a fuselage carrying a front wing (for lift) and a rear wing (for stability). This allows the rider to turn and go up and down.
Other equipment
*Towboat- any boat can be used, but a boat with a tower will help with height and jumping ability as riders begin to advance. For beginners it is recommended to learn at . Advanced riders may increase speed from in order to gain extra height and length on their jumps.
*
Life jacket
A personal flotation device (PFD; also referred to as a life jacket, life preserver, life belt, Mae West, life vest, life saver, cork jacket, buoyancy aid or flotation suit) is a flotation device in the form of a vest or suite that is worn by a ...
- use a jacket marked for water skiing
*Ski line - Available at most boating stores; the line should be at least 75 feet long
*Water sport helmet
Use
![Sky Skier performs jump, 1998](https://upload.wikimedia.org/wikipedia/commons/e/e7/Sky_Skier_performs_jump%2C_1998.jpg)
Unlike
water skiing
Water skiing (also waterskiing or water-skiing) is a surface water sport in which an individual is pulled behind a boat or a cable ski installation over a body of water, skimming the surface on two skis or one ski. The sport requires suffic ...
or
wakeboarding
Wakeboarding is a water sport in which the rider, standing on a wakeboard (a board with foot bindings), is towed behind a motorboat across its wake and especially up off the crest in order to perform aerial maneuvers. A hallmark of wakeboardin ...
, a hydrofoiler's body and the board rise above the water, supported by a pair of front and rear hydrofoil wings which are still under the water. This reduces the drag of the water, allowing for both a smoother ride on rough water and a lesser need for strength.
The rider sits on the seat of the hydrofoil and is strapped in with a seat belt; their feet are strapped into bindings near the front of the board. When the rider is ready the boat will start to tow the skier. The water flowing past the hydrofoil wings generates lift, which can be controlled by the rider to move the board up and down or side to side above the surface of the water. The rider must be centered over the post of the hydrofoil; small body movements will cause great reactions with the hydrofoil. In order to "float" upward the rider leans back while maintaining balance to avoid pitching forward unexpectedly. To go back down the rider leans forward or pushes down with the feet. Turning is accomplished by pointing the knees in the direction desired; the hydrofoil will follow. To jump, the rider leans even farther back. This will give the rider a somewhat stable base to perform aerial tricks for example.
Dangers
Submerged hazards such as trees can be struck by the hydrofoil as low as 3 feet below the surface of the water, causing the rider to fall without warning. Such a fall can be the same as colliding with an object, with the rider impacting the water or the foil. The tow rope can get tangled around the skier or equipment, creating a hazardous condition. After a fall the skier remains strapped to the board; while it will turn upright quickly, there is always the possibility of drowning.
See also
*
Foilboard
A foilboard or hydrofoil board is a surfboard with a hydrofoil that extends below the board into the water. This design causes the board to leave the surface of the water at various speeds.
Background
Laird Hamilton, a prominent figure in the inv ...
*
Paravane (water kite)
The paravane is a towed winged (hydrofoiled) underwater object—a water kite. Paravanes have been used in sport or commercial fishing, marine exploration and industry, sports and military. The wings of paravanes are sometimes in a fixed positi ...
References
{{Reflist
External links
US Hydrofoil Association— Governing body of hydrofoiling in the US—competitions, flyins, and history
Free download of the history of hydrofoiling
— Free royalty free for personal or commercial use
Towed water sports