Luff groove — a vertical slot in a mast or a headstay’s aft face. It accommodates and provides continuous support for the luff of a sail that uses boltrope. A sail is secured at the luff by sliding its luff tape/boltrope into a sail feed and up the luff groove. Optionally, a pre-feeder is positioned before the sail feed to remove wrinkles and minor twists in the sail, so its luff tape/boltrope will slide smoothly into the sail feed. Also called a spar cove. See also: head foil.