kitesail

A kitesail is a propulsion rig for a boat or other vehicle that uses a controllable kite as the source of power instead of, or in addition to, conventional fabric sails. The kite is flown on a tether from the vessel and converts wind energy into forward force through its lift and drag. By adjusting the kite’s altitude, angle of attack, and line tension, a crew can control speed and direction, with the vessel effectively steered by the kite’s position and the vessel’s steering inputs.

Design and components commonly include a kite (often a parafoil, leading-edge inflatable, or other traction kite), a folding or rigid mounting point, and a bridle system that connects the kite to one or more control lines. A control bar, handles, or a remote-control device allows the operator to alter the kite’s edge angles and power. The lines are typically made from high-strength fibers such as spectra or Kevlar, and the kite is deployed and retrieved through a deployment system or mast attachment. Construction materials for the kite itself range from lightweight fabrics to laminated materials, chosen for strength, durability, and depower characteristics.

Operation typically involves launching the kite to a safe height and then using the control system to maintain optimal lift and thrust. Kitesails can be used alone or in combination with conventional sails, enhancing propulsion, especially in certain wind speeds and directions. They require training to manage gusts, line tension, and potential entanglements, and safety features such as quick-release mechanisms are standard.

Applications include sport sailing and experimental kite-powered boats, where a kite can significantly increase drive in favorable wind conditions. The technology has also influenced the development of kite-assisted and kite-towed propulsion concepts for ships.