Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the water, on ice (iceboat) or on land over a chosen course, which is often part of a larger plan of navigation.
A tack is a nautical term both for the lower, windward corner of a sail and, separately, for the windward side of a sailing craft (side from which the wind is coming while under way—the starboard or port tack. Generally, a boat is on a starboard tack if the wind is coming over the starboard side of boat with sails on port side. Similarly, a boat is on a port tack if the wind is coming over the port side of boat.
A point of sail is a sailing craft's direction of travel under sail in relation to the true wind direction over the surface.
A jibe (US) or gybe (Britain) is a sailing maneuver whereby a sailing craft reaching downwind turns its stern through the wind, which then exerts its force from the opposite side of the vessel. It stands in contrast with tacking, whereby the sailing craft turns its bow through the wind.
A staysail ("stays'l") is a fore-and-aft rigged sail whose luff can be affixed to a stay running forward from a mast to the deck, the bowsprit, or to another mast.
In sailing, a cunningham or cunningham's eye is a type of downhaul used on a Bermuda rigged sailboat to change the shape of a sail. It is named after its inventor, Briggs Cunningham, a victorious America's Cup skipper and yacht builder.
A genoa sail is a type of large jib or staysail that extends past the mast and so overlaps the main sail when viewed from the side, sometimes eliminating it. It was originally called an "overlapping jib" and later a genoa jib. It is used on single-masted sloops and twin-masted boats such as yawls and ketches. Its larger surface area increases the speed of the craft in light to moderate winds; in high wind, a smaller jib is usually substituted, and downwind a spinnaker may be used.
A spinnaker is a sail designed specifically for sailing off the wind on courses between a reach to downwind. Spinnakers are constructed of lightweight fabric, usually nylon, and are often brightly colored. They may be designed to perform best as either a reaching or a running spinnaker, by the shaping of the panels and seams. They are attached at only three points and said to be flown.
Running rigging is the rigging of a sailing vessel that is used for raising, lowering, shaping and controlling the sails on a sailing vessel—as opposed to the standing rigging, which supports the mast and bowsprit. Running rigging varies between vessels that are rigged fore and aft and those that are square-rigged.
Sail components include the features that define a sail's shape and function, plus its constituent parts from which it is manufactured. A sail may be classified in a variety of ways, including by its orientation to the vessel and its shape,. Sails are typically constructed out of flexible material that is shaped by various means, while in use, to offer an appropriate airfoil, according to the strength and apparent direction of the wind. A variety of features and fittings allow the sail to be attached to lines and spars.
Tacking or coming about is a sailing maneuver by which a sailing craft, whose next destination is into the wind, turns its bow toward and through the wind so that the direction from which the wind blows changes from one side of the boat to the other, allowing progress in the desired direction. Sailing vessels are unable to sail higher than a certain angle towards the wind, so "beating to windward" in a zig-zag fashion with a series of tacking maneuvers, allows a vessel to sail towards a destination that is closer to the wind than the vessel can sail directly.
Rounding-up is a phenomenon that occurs in sailing when the helmsman is no longer able to control the direction of the boat and it heads up into the wind, causing the boat to slow down, stall out, or tack. This occurs when the wind overpowers the ability of the rudder to maintain a straight course.
The junk rig, also known as the Chinese lugsail, Chinese balanced lug sail, or sampan rig, is a type of sail rig in which rigid members, called battens, span the full width of the sail and extend the sail forward of the mast. While relatively uncommon in use among modern production sailboats, the rig's advantages of easier use and lower maintenance for blue-water cruisers have been explored by individuals such as trans-Atlantic racer Herbert "Blondie" Hasler and author Annie Hill.
An asymmetrical spinnaker is a sail used when sailing between about 90 and 165 degrees from the angle of the wind. Also known as an "asym", "aspin", "A-sail", or gennaker, it can be described as a cross between a genoa (jib) and a spinnaker. It is asymmetric like a genoa, but like a spinnaker, its luff is unstructured and floats freely, unencumbered by an internal wire or hanks attaching it to a stay. Unlike a symmetric spinnaker, the asymmetric does not require a spinnaker pole, since it is fixed (tacked) to the bow or a bowsprit.
Sailing into the wind is a sailing expression that refers to a sail boat's ability to move forward despite being headed into the wind. A sailboat cannot make headway by sailing directly into the wind ; the point of sail into the wind is called "close hauled".
Velocity made good, or VMG, is a term used in sailing, especially in yacht racing, indicating the speed of a sailboat towards the direction of the wind. The concept is useful because a sailboat cannot sail directly upwind, and thus often can not, or should not, sail directly to a mark to reach it as quickly as possible. It is also often less than optimal to sail directly downwind.
Forces on sails result from movement of air that interacts with sails and gives them motive power for sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and sail-powered land vehicles. Similar principles in a rotating frame of reference apply to windmill sails and wind turbine blades, which are also wind-driven. They are differentiated from forces on wings, and propeller blades, the actions of which are not adjusted to the wind. Kites also power certain sailing craft, but do not employ a mast to support the airfoil and are beyond the scope of this article.
A sail is a tensile structure, which is made from fabric or other membrane materials, that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sail-powered land vehicles. Sails may be made from a combination of woven materials—including canvas or polyester cloth, laminated membranes or bonded filaments, usually in a three- or four-sided shape.
The lug sail, or lugsail, is a fore-and-aft, four-cornered sail that is suspended from a spar, called a yard. When raised, the sail area overlaps the mast. For "standing lug" rigs, the sail may remain on the same side of the mast on both the port and starboard tacks. For "dipping lug" rigs, the sail is lowered partially or totally to be brought around to the leeward side of the mast in order to optimize the efficiency of the sail on both tacks.
A tell-tale, in a nautical or sailing context, is a piece of yarn or fabric attached to a sail, a stay, or any rigging on a sailboat. Typically, a tell-tale is on a port and a starboard stay.
