Sailing hydrofoil

A sailing hydrofoil, hydrofoil sailboat, or hydrosail is a sailboat with wing-like foils mounted under the hull. As the craft increases its speed the hydrofoils lift the hull up and out of the water, greatly reducing wetted area, resulting in decreased drag and increased speed. A sailing hydrofoil can achieve speeds exceeding double and in some cases triple the wind speed.

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.