Mainsail

The sail set on the mainmast and normally regarded as the principal sail of that mast.

On a modern sloop or cutter it is usually a fore-and-aft sail with its luff attached to or close to the mast and its foot on a boom or loose-footed. Other rigs use gaff, lug, square or multi-masted arrangements, so it is not necessarily the vessel’s largest sail.

The mainsail provides drive and influences balance, heel and steering. Halyard, outhaul, sheet, traveller, vang, cunningham and reefing systems control its shape and area according to rig, and the boom, sheet and battens create significant handling hazards during tacks, gybes and reefing.