Draft (sail) on:
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In nautical parlance, the draft or draught of a
In nautical parlance, the draft or draught of a sail
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 ...
is a degree of curvature
In mathematics, curvature is any of several strongly related concepts in geometry. Intuitively, the curvature is the amount by which a curve deviates from being a straight line, or a surface deviates from being a plane.
For curves, the canonic ...
in a horizontal cross-section. Any sail experiences a force from the prevailing wind
Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few hou ...
just because it impedes the air's passage. A sail with draft also functions as an airfoil
An airfoil (American English) or aerofoil (British English) is the cross-sectional shape of an object whose motion through a gas is capable of generating significant lift, such as a wing, a sail, or the blades of propeller, rotor, or turbine.
...
when set at an angle slightly greater than the angle of the wind, producing lift which then propels.
The word "belly
Belly may refer to:
Anatomy
* The abdomen, the part of the body between the pelvis and the thorax; or the stomach
** A beer belly, an overhang of fat above the waist, presumed to be caused by regular beer drinking
** Belly dance
* The fleshy, cen ...
" is also used in reference to the draft of a sail (''i.e.'' "More belly in the main sail.").
See also
*Forces on sails
Forces on sails result from movement of air that interacts with sails and gives them motive power for sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and sail-powered land vehicles. Similar principles in a rotating ...
*Sail components
Sail components include the features that define a sail's shape and function, plus its constituent parts from which it is manufactured. A sail may be classified in a variety of ways, including by its orientation to the vessel (e.g. ''fore-and-a ...
References
Nautical terminology {{water-sports-stub