WIND 



23 



3200. "WIND SPEED 



3210. GENERAL. The wind speed is the average speed in knots of the 

 wind blowing over the surface of the sea. The speed will be determined from 

 the size and character of the waves that are running with the wind. Table 

 3-1 will be used to determine the wind speed by the sea condition. 



3220. ENTRY OF WIND SPEED DATA (ff) ON FORM 615-5. Enter two 

 figures for the wind speed (knots) in column 9. Example: 9 knots entered 

 as 09; 15 knots entered as 15. 



3300. TRUE WIND FROM THE APPARENT WIND 



3310. GENERAL. When the surface of the sea cannot be observed, the 

 true wind will be determined from the apparent wind as follows: 



3310.1. Estimate the apparent wind direction to the nearest 10 degrees 

 off the bow of the ship and the apparent wind speed to the nearest 5 knots by 

 observing the effects of the wind on the ship's flag, smoke, or rigging 

 (see Table 3-2). If the ship has an anemometer, the speed of the apparent 

 wind may be obtained from it. 



3310.2. Construct a vector diagram or use 

 wind (see Fig. 2). 



Form 1209 to find the true 



3311. The following may be used to check the results obtained from a 

 vector diagram or from Form 1209: 



3311.1. The true direction of the wind is usually on the same side as, but 

 farther from the bow than the apparent direction. 



664508 O - 62 - 3 



