Draft (sail)

In nautical parlance, the draft or draught of a sail refers to the amount and shape of curvature in a horizontal cross-section.^[1] Any sail experiences a force from the prevailing wind just because it impedes the air's passage. A sail with draft also functions as an airfoil when set at an angle slightly greater than the angle of the wind, producing lift which then propels the vessel.^[1]

Influence of mainsail draft position on forward and side force

The word "belly" is also used in reference to the draft of a sail (i.e. "More belly in the main sail.").

See also

• Forces on sails
• Sail components