Ahoy Sailors, now that you can identify the different sails that power your boat, it’s time to learn what each of those sails do. Stay tuned for the next lesson, which will explain how to properly anchor your boat.
SOUTHERN CALIF.— A sail provides propulsive force via a combination of lift and drag, depending on its angle of attack- its angle with respect to the apparent wind. Apparent wind is the air velocity experienced on the moving craft and is the combined effect of the true wind velocity with the velocity of the sailing craft. The angle of the sail is the difference between the direction your boat is heading and the direction of the wind. Different angles of sail, called points of sail, change as your boat changes course, and the sails must be adjusted to harness the wind as efficiently as possible.
Mainsail: The mainsail is the predominant sail on a sailboat and is set on the after side of the mainmast. The jib (and the staysail if you have a cutter) create the lift that drives your sailboats to windward. And little affects our sailboats’ handling characteristics than a poorly trimmed mainsail.
Headsail: Your headsail connects from the bowsprit or the deck by a rod, wire, or rope, keeping the sail in one position. Depending on the shape of your headsail, it could be referred to as a jib. This specialty staysail (a type of headsail) goes in front of your sailboat’s mast.
Spinnaker: A spinnaker is a sail designed specifically for sailing off the wind from a reaching course to a downwind. For example, with the wind 90–180 degrees off the bow. When deployed, the spinnaker fills with wind and balloons out in front of the boat. This is called flying.
Mainsail vs. Jib: The jib gives control over the bow (front) of the ship, making it easier to maneuver the boat. The mainsail provides control over the stern of the ship. The jib is the headsail (front sail) on a front-and-aft rig. The size of the jib is generally indicated by a number – J1, 2, 3, and so on.
Different parts of the mainsail:
Head: The head is the top edge of the sail. This is different from the three-sided sail, where the head refers to a corner.
Luff: The luff is the forward or leading edge of a sail.
Leech: Modern sails may come with a standard leech line (leech control) that runs under the back edge of the mainsail. This line is usually fixed at the head of the sail, and the other end can be cleated near the sail’s clew. In strong winds, particularly when sailing upwind, the leach of the sail may begin to flutter.
Batten: Battens are the primary structure of a mainsail. They support the sail’s shape, improve overall durability by limiting the effects of flogging on fabric, and remove any limitation on size (roach area). Full-length battens in the top sections of the sail are now more common.
Clew: The corner where the leech and foot connect is called the clew on a fore-and-aft sail. On a jib, the sheet is connected to the clew; on a mainsail, the sheet is connected to the boom (if present) near the clew. Clews are the lower two corners of a square sail.
Foot: The foot is the bottom edge of a sail. Loose-foot refers to a mainsail which does not have a foot not attached to the boom. The tack and clew secure the lower sail in place, and the foot floats freely. An attached foot is a mainsail with the foot secured to the boom by slides, slugs, or boltrope.
Tack: The tack is the name for the lower corner of the sail closest to the mast, between the luff and the foot is the tack. The tack is attached to the boat or a spar.