{{About, , the forward edge of a sail, Parts of a sail, other uses, Luff (disambiguation){{!Luff
In
sailing
Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the ''water'' (sailing ship, sailboat, raft, windsurfer, or kitesurfer), on ''ice'' (iceboat) or on ''land'' (land yacht) over a chosen cou ...
, luffing refers to when a sailing vessel is steered far enough toward the direction of the wind ("
windward
Windward () and leeward () are terms used to describe the direction of the wind. Windward is ''upwind'' from the point of reference, i.e. towards the direction from which the wind is coming; leeward is ''downwind'' from the point of reference ...
"), or the
sheet controlling a sail is eased so far past optimal trim, that airflow over the surfaces of the sail is disrupted and the sail begins to "flap" or "luff" (the
luff of the sail is usually where this first becomes evident). This is not always done in error; for example, the sails will luff when the bow of the boat passes through the direction of the wind as the sailboat is
tacked.
A sailboat can also be "luffed" slightly without completely de-powering the sails. Often this occurs on the
point of sail known as
close hauled
A point of sail is a sailing craft's direction of travel under sail in relation to the true wind direction over the surface.
The principal points of sail roughly correspond to 45° segments of a circle, starting with 0° directly into the wind. ...
, this is sometimes referred to as
pinching or "feathering" and is sometimes done deliberately in order to make a more direct course toward an upwind destination (see: "
beating to windward"), or to "de-power" a sail on a windy day to maintain control of the sailboat. "Luffing" can also be used to slow or stop a sailboat in a controlled manner. To offset luffing at the top of the sail one should move the sail "lead" forward until the point where the "telltales" break evenly.
Luffing is also a process of
power kites when they stall and the front (or leading) edge falls downwards.
Sailing manoeuvres