reefing

thumb|Reefed Sail thumb|Gaff sail, showing reefing cringles (13), reefing points (20) and reefing lines (21)

In sailing, reefing is the practice of reducing the area of a sail to preserve a sailing vessel's stability in strong winds. This is usually achieved by folding or rolling one edge of the canvas in on itself and attaching the unused portion to a spar or a . Restoring full sail area is termed shaking out a .