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
Wind assistance have been rare. Tatyana Chernova greatly outperformed the current world junior record of 6542 points with a wind-assisted score of 6768 points in June 2007 in Arles, France. Other wind-assisted series from Arles were recorded in 1987 and 2006. There is no wind speed rule for road events, but the start and finish points of a course, measured along a theoretical straight line between them, shall not be further apart than 50% of the race distance to be allowed as a record. This is due to the wind advantage that might take place for a straight course. The Athens Classic