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
Propeller speed reduction unit of sound. Factory-certified aircraft engines have also used reduction units integral to their design. The Cessna 175 used a geared unit which is part of the Continental GO-300 engine while the Helio Courier and several Beechcraft twins, among others, used the geared Lycoming GO-435 and GO-480. Many light sport aircraft use engines from Rotax such as the Rotax 912 which incorporates a geared reducer. Propeller speed reduction unit A propeller speed reduction unit is a gearbox or a belt and pulley device used to reduce the output revolutions per minute (rpm) from the higher input rpm of the powerplant. This