INTRODUCTION TO SONAR 



A sample logsheet is illustrated in figure 

 5-19. Information pertaining to one BT drop 

 is supplied on the form. The environmental half 

 of the logsheet requires completion of 14 items. 

 The radio message portion has 7 data units, 

 plus spaces for the necessary trace readings. 



ENVIRONMENTAL DATA ENTRIES 



In the heading of the environmental data 

 section, record your ship's name and hull num- 

 ber, country, sheet number, and sponsoring 

 activity. Spaces for cruise and station numbers 

 are for special assignments. If an apparent 

 malfunction of the BT occurs, include pertinent 

 information at the bottom of the sheet under 

 "Remarks." Successive logsheets ai-e numbered 

 consecutively. 



Item 1 — BT Instrument Number 



The number is stamped on the nose of the 

 BT. Always include any letter used as a prefix 

 or suffix to the number. Compare the number 

 stamped on the BT with the number on the BT 

 grid. The two numbers MUST agree. 



Item 2 — Slide Number 



Number the slides consecutively, starting with 

 number 1 for the first BT reading fallen after 

 leaving port. 



Item 3 — Date 



Day and month are given according to Green- 

 wich date. Record the last two digits of the 

 year. 



Item 4 — Time 



Record the GMT hour and minute at which 

 the BT entered the water. 



Items 5 and 6 — Latitude and Longitude 



Record the degrees, minutes, and hemisphere 

 (N or S, E or W) at the time of lowering the BT. 

 Prefix with zero when necessary to complete 

 the degrees boxes. Example; Latitude 8° is 

 recorded as 08; longitude 27° is recorded as 027. 



Item 7 — Water Depth 



Enter depth obtained by sounding at time of 

 lowering BT. Check appropriate box to indicate 

 fathoms or meters. 



Item 8 — Wind 



Enter true wind direction, to the nearest 10°, 

 using the appropriate code from the accompanying 

 list. Record the true wind speed in knots. 



Item 9 — Air Temperature 



Record the dry and wet bulb air temperatures, 

 to the nearest 0.1°, and check thf appropriate 

 box for °F or °C. If centigrade temperature is 

 less than 0°, add 50.0 to the actual reading (-2°C 

 is entered as 52.0). Enter a dash above the first 

 (tens) digit to indicate Fahrenheit readings below 

 0°. 



Item 10 — Barometric Pressure 



Use millibars, to the nearest tenth, to record 

 barometric pressure, omitting the thousands and 

 hundreds digits (1011.2 mb = 11.2). Table 5-3 

 is used in converting inches to millibars. 



Item 11 — Weather 



Record present weather (WMO code 4501) 

 as follows; 



Clear (no cloud at any level). 



1 Partly cloudy (scattered or broken). 



2 Continuous layer(s) of cloud(s). 



3 Sandstorm, duststorm, or blowing snow. 



4 Fog, thick dust, or haze. 



5 Drizzle. 



6 Rain. 



7 Snow, or rain and snow mixed. 



8 Shower(s). 



9 Thunderstorm(s). 



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