III TACKING
 

Two Methods of Coming About  Sailors can turn a craft in one of two ways. Steering the vessel from one 45° tack to the opposite (left) is successful provided the boat does not lose too much inertia when it is pointed directly into the wind and sails are luff, or toward the wind. A potentially dangerous way to come about is jibing (right). In this procedure, the wind fills the sails from behind. Turning the vessel causes the boom to swing quickly from one side to the other. If this movement is not controlled, the craft may lose balance and crew may be knocked overboard. © 1993-2003 Microsoft Corporation. All rights reserved.

If boats were able to sail only before the wind and off the wind, it would be impossible to reach a destination upwind from the starting point. By sailing on the wind, however, a sailboat can make a course approximately 45° away from the wind direction, as shown in the diagram in Figure 1. By sailing a succession of such courses, first to the left and then to the right of the wind direction, a maneuver called tacking, sailboats can zigzag in an upwind direction, as shown in Figure 2. A vessel is said to be on the starboard tack when sailing so that the wind is blowing from the right or starboard side, and to be on the port tack when the wind is blowing from the left or port side.
 

The procedure of shifting a vessel from one tack to the other, called coming about, may be accomplished in either of two ways. The boat may be steered so that its bow (the front end) points up into the wind and then away from the wind on the opposite tack. As the boat points into the wind, it loses speed, the sails being pressed directly backward by the wind. Then as the bow moves away from the wind on the other tack, the sails fill with wind again and assume a position on the other side of the vessel. During the time of coming about, the boat is receiving no motive force from the wind; it must rely on its inertia to maintain enough speed so that it can be steered onto the opposite tack. When the boat does not have sufficient inertia and stops with its bow pointing into the wind and its sails useless, it is said to be in irons.

The other method of changing tack consists of steering the boat away from the direction of the wind, until the wind fills the sails from the other side and the boat is on the other tack. In fore-and-aft-rigged vessels, this maneuver is called jibing or gybing, and in square-rigged ships it is known as wearing. When running before the wind, a slight shift of wind may cause a boat to jibe unintentionally. Such jibing is dangerous because of the speed with which the heavy booms, or spars, at the foot of the sails sweep across the decks of the vessel from one side to the other, and also because of the danger of breaking spars. In wild jibing, control can be lost momentarily and, if the seas are high, a small boat can broach—that is, veer on its side with danger of swamping or capsizing. An unintentional jibe in a heavy wind frequently has enough force to break the masts of a vessel. When jibing intentionally, careful sailors always haul in on the boom while turning, so that the boom will travel only a short distance when the wind reaches the other side of the sails.