Before revision: Note that a number of additional factors come into play when converting the measurements from the masthead anemometer into the true wind if a high degree of accuracy is required, including the following: Leeway (or drift on power vessels) - it is very seldom that a craft is pointing in the direction it is going, and on a sailboat the angle of leeway is the difference between the heading of the craft and its actual track through the water .
After revision: Note that a number of additional factors come into play when converting the measurements from the masthead anemometer into the true wind if a high degree of accuracy is required, including the following: Leeway (or drift on power vessels) - Factors like water currents or slipping sideways due to wind (leeway) mean that the direction a craft is pointing often does not exactly match its actual direction of travel .