Sail

The tack is the lower corner of the sail's leading edge. On a sloop rigged sailboat, the mainsail tack is connected to the mast and the boom at the gooseneck. On the same boat, a foresail tack is clipped to the deck and forestay.

Maneuver

A tack or coming about is the maneuver by which a sailing boat or yacht turns its bow through the wind so that the wind changes from one side to the other. This is in distinction to a jibe (also known as wear or wearing during the age of sail), which is turning the stern of the boat through the wind.

Tacking is also incorrectly referred to as beating, the general process by which a ship moves on a zig-zag course towards the direction that the wind is coming from. As no sailing vessel can move directly against the wind—while necessity may dictate that it should go into just that direction—beating allows the vessel to advance against the wind direction. Commonly the closest angle a yacht can sail to the wind is around 35 to 45 degrees.

This is done by turning as close into the wind as practicable and then, after a time of sailing, reversing tack to gain back the sideways displacement that occurred during the first tack. Depending on how much sideways space there is (from a small navigable channel to a full ocean) tacks may be minutes or even days in between.

Historically, sailing vessels were very bad at sailing against the wind, especially square-rigged ships. This has steadily improved, with modern yachts being able to almost—but not quite—move against the wind direction.

Procedure

In small boats with low booms, the skipper should generally announce, "Ready about" to prepare the crew for the tack and the swinging of the boom, which can otherwise cause serious injury to an unprepared crew member. Upon the acknowledgment of the crew, the skipper announces, "Coming about," or alternatively "Helm's a-lee", "Hard a-lee", or "Lee Ho" during the actual tacking.

Before tacking, it is a good practice to have a considerable amount of speed in order to complete the tack. If a vessel hasn't enough speed to complete a tack, the wind may overpower the boat's turn, thus forcing it back on its previous course, or the vessel may find itself "in irons," not moving at all.

An auto tack is a modern term referring to when a sailboat turns its bow through the wind by accident. This usually occurs in one of two circumstances: either when a steady hand is not kept on the tiller or steering wheel, or when a sudden and large wind shift occurs, such as in a narrow river or lake, causing the wind to come from the other side of the sail even though the boat has not changed course. Auto tacks are more likely to occur when a sail boat is close hauled but may happen on any point of sail.

Beating to windward refers to the process of beating a course upwind, and generally implies (but does not require) actually coming about.

When used without a modifier, the term "tacking" is always synonymous with "coming about"; however, one can also "tack downwind"; i.e., change tack by jibing rather than coming about. The reason racing sailboats do this is that most modern sailboats (especially larger boats with spinnakers and a variety of staysails) sail substantially faster on a broad reach than running dead before the wind. The extra speed gained by zigzagging downwind more than makes up for the extra distance that must be covered. Cruising boats also often tack downwind when the swells are also coming from dead astern (i.e., there is a "following sea"), because of the more stable motion of the hull.

Position

As a noun, tack describes the position of a sailboat with respect to the wind and is primarily important as relates to the rules of the road that define which boat has right-of-way when two boats converge. Informally a sailboat's "Tack" is defined by the windward side of the boat at any particular moment-- if the port (or left) side is "to windward", the sailboat is said to be on the "port tack". The "windward" side is not always the side where the wind is coming from tough, a boat that is "running" with the wind has the wind coming over it's stern and a boat that is in the act of tacking passes through a zone where the wind is coming from directly ahead. For the purposes of right of way rules we therefore define a sailboat's windward side, and therefore the "tack" the boat is on, as being the side opposite the boom; or in the case of a sailboat with multiple masts, the side opposite the mainsail boom. In most cases A sailing vessel on a port tack must always give way to another sailing vessel on starboard tack by both the rules of the road and racing rules.
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