Apparent wind in knots and degrees. 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: In the presence of a current, the true wind is considered to be that measured on the craft drifting with the water over the bottom, and wind with respect to the sea bed as the "ground" or "geographical wind". The apparent wind on board (a boat) is often quoted as a speed measured by a masthead transducer containing an anemometer and wind vane
Variable speed wind turbine as noise levels, this is not possible for the full range of sub-rated wind speeds. Below the rated wind speed, the following operating strategy is employed: Above the rated wind speed, the pitching mechanism is employed. This allows a good level of control over the angle of attack, thus control over the torque. The previous torque rotor-speed diagrams are all plots when the pitch angle, formula_38, is zero. A three dimensional plot can be produced which includes variations in pitch angle. Ultimately, in the 2D plot, above rated wind speed, the turbine will operate at the point marked 'x' on