Ski like protrusion that holds the front of a vesel out of the water when at speed. Aids economy, reduces drag. Search for Hydrofoil books on Amazon.co.uk

A wing-like structure that raises part or all of a powerboat's hull out of the water.

A surface immersed in water underneath the planing bottom of a hull or float to assist take-off with its hydrodynamic lift.

A marine wing. When it moves through the water a hydrofoil creates lift, which lifts the vessel or animal it is attached to out of the water.

hi-dro-foil A boat equipped with a device consisting of planes for lifting its hull out of the water to increase its speed.

a device consisting of a flat or curved piece (as a metal plate) so that its surface reacts to the water it is passing through; "the fins of a fish act as hydrofoils"

a speedboat that is equipped with hydrofoils that lift it so that it skims the water at high speeds; "the museum houses a replica of the jet hydroplane that broke the record"

a boat that uses foils, or wing-shaped blades, to rise out of the water

a boat, which runs on foils, or vanes that raise the vessel out of the water

a "lifting" surface

an underwater wing (as seen in this diagram)

a watercraft that skims the top of the water with only two wing-like things touching the water

a wing-like surface that provides lift to the watercraft it supports

a wing that 'flies' in water

a fast boat designed to have its hull lifted clear of the water surface and supported by foils or wings when it reaches cruising speed

A hydrofoil is a boat with wing-like foils mounted on struts below the hull. As the craft increases its speed the hydrofoils develop enough lift for the boat to become foilborne - i.e. to raise the hull up and out of the water. This results in a great reduction in drag and a corresponding increase in speed.