Sailing hydrofoil

Both monohull and multihull sailboats can be retrofitted with hydrofoils, although greater stability can be achieved by using the wider planform of a catamaran or trimaran.

On catamarans, a single main foil can be attached between the hulls just in front of the center of gravity and at 2 degrees of incidence, spanning the tunnel with supporting struts.

Monohull boats typically employ a "ladder" arrangement of hydrofoils splayed out with a dihedral angle of 50 degrees, with a stabilizing rudder foil.

Subsequently, Garth and John Ilett in Perth, Australia developed a two-hydrofoil system for the Moth with active flap control for the main foil via a surface sensor.

Fasta Craft's Prowler design, superseded in 2008 by the F-Zero, features a carbon-fiber hull, inverted "T" foils on the centerboard and rudder, and can reach speeds of over 27 knots.

Fasta Craft has since been joined in producing hydrofoil Moths by several other companies, including Bladerider, Assassin, Exocet, and Aardvark Technologies.

All World Championships since 2004 have been won by hydrofoil-equipped Moths, which can become foilborne in as little as six knots of breeze when steered by an experienced sailor of lighter weight.

The largest difference between the two classes is that the Wazsp is heavier due the foils being constructed out of aluminum instead of carbon fiber.

Due to heavier design, the top speed of the waszp is only 26.7 knots, however its cheaper materials have made it a popular and accessible class, despite its relative youth.

Most recently, the Waszp class has partnered with SailGP to develop a pathway for young sailors to work their way into the professional field of sailing.

The newly founded one-design class had its first racing series in 2020, starting in Europe and then making its way over to the United States in 2022.

Speeds of 50 knots were predicted based on computer simulations [9] and in fact have been exceeded in the Prada Cup by the America Magic's boat in January 2021.

Under the terms of the protocol, these daggerboards could not feature trim tabs, could not exceed the beam of the boat when raised and could not be adjusted when lowered, but a loophole exploited by three teams was to create T-shaped rudders and L-shaped daggerboards of which the leeward appendage serves as a hydrofoil on all points of sailing conditions in winds over 10 knots.

The boat also has a variety of rudder foils, board foils, wingssails, and jibs to be used in various combination with a crew of 3-5 people based on the wind speeds There currently exists a total of 8 active boats with teams from the United States, Spain, Japan, France, Denmark, Australia, New Zealand, and Great Britain.

[18] International A-class catamaran rule 8 initially allowed hydrofoils, but was changed to partially restrict them in 2009, in response to improving technology.

The rule required "that all foils must be inserted from the top of the hull, and that there must be a minimum distance between the tips of the bottom of the boards of 75cm from the centreline".

[19] The 2014 A-Class Catamaran World Titles in Takapuna New Zealand demonstrated early foiling capabilities to the class.

For the 2017 World Championships, the Nacra was upgraded to a fully foiling yacht, to be raced at the 2020 Tokyo Olympics.

Sailing the boat in subpar wind conditions proved to be easier and more enjoyable than a Waszp or Moth as the catamaran hulls provided increased stability.

[26] In the 1990s the Hobie Cat company manufactured the TriFoiler (no longer in production), a twin-sail trimaran with a mainsail on each outrigger capable of 35+ knot speeds in typical sailing conditions, making the TriFoiler the fastest production sailboat in the world.

The prototype of the Hobie TriFoiler, called Longshot, was developed by brothers Dan and Greg Ketterman in conjunction with Russell Long.

Though more streamlined than the Trifoiler and having smaller hydrofoils, Longshot still holds the Class A speedsailing record of 43.55 knots on a 500-meter course, set in Tarifa Spain in 1993.

Many of the hydrofoils used in windfoiling can vary in size in order to obtain a greater combination of lift and top speed.