Mainsail

The luff is bent on with slides or slugs feeding a track on the aft face of the mast on most cruisers, or with a sewn-in bolt rope feeding a mast groove on traditional boats. The tack is made fast at the gooseneck, the clew is hauled aft along the boom by the outhaul, and the sail goes up on the main halyard — head to wind, so the cloth can rise without filling.

Usually woven polyester on cruising boats, laminate on performance boats. Battens support the roach — the sail area outside the straight head-to-clew line, which cloth tension alone cannot hold. Full battens run from luff to leech for a quieter sail that keeps its shape; simpler mains carry shorter leech battens. A rigid headboard at the head spreads the halyard load.

There is no wind range to memorize for the mainsail because you do not change it — you shorten it. Reef early: the time to reef is when you first ask yourself whether you should. Upwind, trim with the mainsheet and position the boom with the traveler; once the sheet is eased on a reach, the vang takes over leech control. Watch the leech telltales — streaming means attached flow, a permanently stalled top telltale means the leech is too closed.