The direction of the wind as it appears to those on board a sailing vessel. It differs from the true wind in speed and direction by an amount which can be worked by a vector diagram: the vessel's speed through the water being represented by one leg of a triangle of which the true wind and the apparent wind form the other two sides. The difference between the true wind and the apparent wind is most pronounced when the true wind blows from directly abeam, and is reduced as the vessel sails closer to, or further off, the true wind. It disappears completely with the wind from dead astern. It is to the apparent wind, not the true, that a sailing vessel trims her sails. In the diagram the strength of the wind has been taken as 12 knots and the speed of the vessel as 4 knots.
True and apparent wind
Subjects: Maritime History.