Sailing into the wind

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Sailing into the wind is a sailing expression that refers to a sail boat's ability to move forward despite being headed into (or very nearly into) the wind. A sailboat cannot make headway by sailing directly into the wind (see "Discussion," below); the point of sail into the wind is called "close hauled".

Sailing into the wind is possible when the sail is angled in a slightly more forward direction than the sail force. In this aspect, the boat will move forward because the keel (centerline), of the boat acts to the water as the sail acts to the wind. The force of the sail is balanced by the force of the keel. This keeps the boat from moving in the direction of the sail force. Although total sail force is to the side when sailing into the wind, a proper angle of attack moves the boat forward.^[1]

Another way of stating this is as follows:

The more the sail is angled from the centerline of the hull, the more the force points forward rather than to the side. Combine that slight adjustment in forward force with the opposition of water to air, and we have a boat shooting windward because it is now the course of least resistance.^[1]

In practice, optimal sailing in the direction from which the wind is coming will usually be at a course of around 45-degree angles to the oncoming wind. To reach a particular point, alternating the direction of the wind between the port and starboard side is usually necessary. This is called "tacking."