Chapter 5 — BATHYTHERMOGRAPH 



be in centigrade. If you have only a Fahrenheit 

 thermometer, you can convert the readings to 

 degrees centigrade by using the formula: 5/9 

 (F°-32). If an observation is missed, insert 

 XXX in the temperature space for that hour. 

 Do not try to extrapolate. 



Identification 



Enter your ship's name and hull numiier, and 

 the date at the top of the sheet. 



Message Prefix 



Each message contains the prefix CTEM, 

 together with a code letter indicating the instru- 

 ment used to measure the temperature. The 

 code letters are; (N) injection thermistor; (B) 

 bucket thermometer; (J) injection thermometer; 

 (O) some other device, which must be specified. 

 Instrument preference is in the order listed. 



Date 



Enter 

 the yeai'. 

 numerals 

 the year. 



the day of the month, the month, and 

 The day and the month will contain two 

 each. Use only the last numeral for 



Position 



Octant, latitude, and longitude are recorded 

 for each reading. See items 4, 5, and 6 in the 

 radio message section of the BT log for proper 

 method of making entries. Each entry is to be 

 the position of the ship at the exact time of 

 taking the temperature reading. 



Observation 



Enter the GMT hour and the sea temperature 

 to the nearest 0.1°C. When the temperature is 

 below zero, add 50 to the absolute value. 



Ending 



The message must end with the numerals 

 19991. 



EXPENDABLE BATHYTHERMOGRAPH 



Many undesirable features are connected with 

 the use of the mechanical BT and its associated 

 equipment. The most unwelcome aspect is that 

 the ship conducting a BT drop must maintain 

 a slow speed and steady course. The deeper 



71.118 

 Figure 5-24. — Expendable BT probe in its cannister. 



87 



