Loose Cover Meaning in Sailing

A loose cover (or ‘loose-footed’) describes a mainsail that is not permanently attached to the boom along its bottom edge (the foot). Instead, the sail is only attached at the two corners—the ‘tack’ at the mast and the ‘clew’ at the end of the boom. This allows the sail to take on a more natural, efficient aerodynamic shape and makes it easier to adjust the depth of the sail’s curve. One clear example involves a sailor using the outhaul to pull a loose-footed sail tight, flattening it for better performance in a strong breeze. This design is common on modern performance yachts because it improves air flow and reduces wear on the boom. It also makes removing and storing the sail much simpler for the crew.