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Sailing hydrofoils achieve boat speeds up to twice the speed of the wind, as did the AC72 catamarans used for the 2013 America's Cup. [20] Ice boats can sail up to five times the speed of the wind. [21] [22] Lateral force is a reaction supplied by the underwater shape of a sailboat, the blades of an ice boat and the wheels of a land sailing craft.
A sail is a tensile structure, which is made from fabric or other membrane materials, that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sail-powered land vehicles. Sails may be made from a combination of woven materials—including canvas or polyester cloth, laminated membranes or ...
So, one can expect gusts to be about 1.5 times stronger than the prevailing wind speed (a 10-knot wind might gust up to 15 knots). This, combined with changes in wind direction suggest the degree to which a sailing craft must adjust sail angle to wind gusts on a given course. [83]
Sailing – the use of wind to provide the primary power via sail(s) or wing to propel a craft over water, ice or land. A sailor manages the force of the wind on the sails by adjusting their angle with respect to the moving sailing craft and sometimes by adjusting the sail area.
The catamarans used for the 2013 America's Cup were expected to sail upwind at 1.2 times the speed of the true wind, and downwind at 1.6 times the speed of the true wind. [6] [7] [8] They proved to be faster, averaging about 1.8 times the speed of the wind with peaks slightly over 2.0. [9]
Spring sails were invented by Scottish millwright Andrew Meikle in 1772. The sail is divided into a number of bays, each having a number of shutters. All the shutters are joined together by a shutter bar, and the force required for the wind to open the shutters is adjusted by a separate spring on each sail. Although automatic in operation, the ...
Apparent wind velocity provides the motive power for the sails on any given point of sail. The apparent wind is equal to the true wind velocity for a stopped craft; it may be faster than the true wind speed on some points of sail, or it may be slower e.g. when a sailing craft sails dead downwind. [18]
A spinnaker is a sail designed specifically for sailing off the wind on courses between a reach (wind at 90° to the course) to downwind (course in the same direction as the wind). Spinnakers are constructed of lightweight fabric, usually nylon, and are often brightly colored. They may be designed to perform best as either a reaching or a ...