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Tack (sailing)
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Tack is a term used in sailing that has different meanings in different contexts.
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.
ack is the alignment of a sailing vessel with respect to the wind when moving upwind: that is, when the vessel's bow is pointed within 90 degrees of the wind.
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Encyclopedia
Tack is a term used in sailing that has different meanings in different contexts.
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.
Position
Tack is the alignment of a sailing vessel with respect to the wind when moving upwind: that is, when the vessel's bow is pointed within 90 degrees of the wind. If the wind is to starboard, the vessel is on "starboard tack", and if to port, on "port tack".
The "rules of the road" for ships and boats declare that when the courses of two sailing vessels converge, the vessel on port tack must give way to a vessel on starboard tack . For this purpose, port and starboard tack include any position with the wind to that side, whether moving upwind or downwind. If a vessel is fore-and-aft-rigged, the actual wind position is overridden by the position of the boom (the mainsail boom in a vessel with multiple masts), which is assumed to be on the side opposite the wind, even if the vessel is running straight downwind or is in the act of tacking; that is, if the boom is to port the vessel is on starboard tack, and vice versa. There are exceptions to the requirement to give way: in particular, if the vessel on port tack does not have sea-room to tack or maneuver out of the way.
Maneuver
Tacking or coming about is the maneuver by which a sailing vessel turns its bow through the wind so that the wind changes from one side to the other. For example, if a vessel is sailing on a starboard tack (with the wind to starboard) and tacks, it will end up on a port tack, with the wind to port. See the image at the right; the red arrow indicates the wind direction.
Tacking is distinct from jibing, where the ship's stern passes through the wind.
Tacking is sometimes confused with beating (see below).
Procedure
Notify your crew that you are tacking, so they are aware of the boom switching sides and watch their heads.
As a crew, you may hear one of many terms such as: Coming about, Helm's a-lee, Hard a-lee, or Lee Ho during the process.
The next step as a skipper, is to push the tiller towards the sail or away from you (assuming you are facing your sail and the boom is away from you).
You will hear an intense racking/fluffing/banging noise of your sail. This is good. It means you are facing directly into the wind (essentially your sail is a flag) marking the half way point through your tack.
When the noise stops, your sail will calm down and begin to form a smooth curve again. This means you have completed your tacking process and now your vessel is on a different tack (port vs. starboard).
At this point you should still be facing your sail and the boom away from you. This means that you would have had to switch sides in your vessel as the boom switched sides during the tack. Timing, precision and comfort are all factors into form of tacking and are purely dependent on the sailor's preference. However, there is a type of tack known as a roll tack which does have a uniform, "right" way of being completed.
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. The loud noise won't go away at this point and in most cases, your vessel will begin to go backwards as it has no power to fight back the wind which may push back your vessel. This event is most commonly known as "getting stuck in irons"
An auto tack is a modern term. It refers to a sailing vessel turning its bow through the wind by accident. There are two ways this usually occurs. If the helmsman does not have a steady hand on the tiller or steering wheel, the vessel may yaw. Or the wind may shift suddenly from one direction, crossing the bow even though the vessel has not changed course. Auto tacks are more likely to occur when a sailing vessel 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. Racing sailboats do this because 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.
Beating
Beating is the procedure by which a ship moves on a zig-zag course in the direction that the wind is blowing from. No sailing vessel can move directly against the wind, but that may be the direction it wants to go. Beating allows the vessel to advance against the wind direction.
A ship that is beating will sail as close to the wind as possible; this position is known as close hauled. In general, the closest angle to the wind that a ship can sail is around 35 to 45 degrees. Some modern yachts can sail very near to the wind, while older ships, especially square-rigged ships, were much worse at it.
Thus when a ship is tacking, it is moving both upwind and across the wind. Cross-wind movement is not desired, and may be very much undesirable, if for instance the ship is moving along a narrow channel, or the destination is directly upwind.
Therefore the ship changes tack periodically, reversing the direction of cross-wind movement while continuing the upwind movement. The interval between tacks depends on the lateral space available: in a a small navigable channel, tacks may be required every few minutes, while in the open ocean days may pass between tacks.
In older vessels that could not sail close to the wind, beating could be a tiresome process that required sailing a total distance several times the distance actually travelled upwind.
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