AEROGRAPHER'S MATE 3 & 2 



NWSC 3140/8 Entries 



WIND (COLS. 12, 13, & 14). — Enter the 

 TRUE wind direction, wind speed (in knots), 

 wind shifts, gustiness, and squalls in accordance 

 with instructions for columns 9, 10, and 11 

 of MF1-10. The difference between land station 

 wind observations and shipboard wind obser- 

 vations is that compensation must be made 

 for the ship's heading and speed, and true wind 

 direction and speed have to be computed; they 

 cannot be observed directly. 



Several methods for computing the true wind 

 at sea are available. Two of these methods, 

 the True Wind Computer CP-264/U and the 

 True Wind Observing Method, will be discussed 

 in detail later in the chapter. 



When wind indicating or recording equip- 

 ments is inoperative or unavailable, estimate 

 wind speeds in accordance with criteria listed 

 in Appendix VI. This appendix may also be 

 used to check computed wind speeds. Wind 

 directions may be estimated by observing the 

 direction of travel of sea waves. Remember that 

 such directions are relative to the ship's 

 heading, and they must be converted to true 

 directions. 



SUMMARY OF THE DAY (COLS. 52 through 

 56). — Enter the maximum wind data for the 

 period from midnight to midnight GMT. Enter 

 estimated wind data if recording equipment is 

 not available. 



In column 52, enter times to the nearest 

 minute GMT. In columns 53 and 54, enter the 

 positions to the nearest whole degree latitude 

 and longitude. In columns 55 and 56, wind 

 direction and speed is entered as it was entered 

 in columns 12 and 13 of NWSC 3140/8. Directly 

 beneath these column entries, space is provided 

 for entries of gale conditions or greater (34 

 kns or higher) if the ship is steaming north 

 of 30°N. or south of 30°S. If the ship is steaming 

 between 30°N. and 30°S., make entries in these 

 columns if the wind is 22 knots or greater. 



Wind Recorder Charts 



Wind recorder charts from the RD-108/ 

 UMQ-5 and GMQ-29 recorders are handled in 

 the following manner: 



1. At the beginning and end of each chart 

 roll, enter station name (NAS, etc.), date and 

 time that record began/ended, and chart feed 



rate if different from normal, or if times 

 are not printed on the chart. 



2. Change charts at 0000 LST on the first 

 day of each month and at intermediate times 

 as necessary to prevent loss of record. 



3. Replace charts in original shipping carton 

 if available, and enter the station name and 

 period of record on the end of the carton. 

 Forward completed charts monthly in accord- 

 ance with instructions in chapter 11 of 

 this training manual. 



4. Power and equipment failure is indicated 

 on the recorder chart by entering the term 

 "POWER FAILURE" or "EQUIPMENT FAIL- 

 URE" at the point of failure, along with the 

 time (LST) of the failure. When returned to 

 service, the chart should be adjusted to the 

 correct time and a time check entered. 



WIND MEASURING SET 

 AN/PMQ-3( ) 



OPERATION 



Wind Measuring Set AN/PMQ-3, -3A, -3B, 

 and -3C is a portable hand anemometer. It 

 is a combination wind direction and speed 

 indicating unit which indicates direction to 360° 

 and speed from to 60 knots. The wind, 

 upon striking the small cylindrical turbine 

 (fig. 3-1) in the transmitter causes the turbine 

 to rotate. The turbine is linked to a small 

 electrical generator which produces a voltage 

 proportional to the speed of the turbine. The 

 voltage is transmitted to the indicator, which 

 is a voltmeter graduated in knots. The indicator 

 has 2 scales, graduated from to 15 knots and 

 from to 60 knots. The upper trigger on the 

 handle controls the scale to be used. 



The direction unit is a twin-tailed assembly 

 with a pointer (vane nose), which faces into 

 the wind, when the brake is released by 

 depressing the vane locking trigger. The index 

 pointer on the vane is then aligned on the 

 direction dial with the direction from which the 

 wind is blowing. To make an accurate direction 

 reading, follow this procedure: 



a. Choose a location where there will be, 

 as nearly, as possible, unobstructed wind flow 

 from all directions. 



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