Chapter 5— BATHYTHERMOGRAPH 



At a temperature of 105°F, the recording 

 stylus moves against a stop pin. If this tempera- 

 ture is exceeded, the calibration of the instrument 

 becomes ruined, perhaps permanently. For this 

 reason, the BT must always be kept out of the 

 sun and away from the vicinity of firerooms, 

 steampipes, and other sources of heat. An in- 

 strument that has been overheated may have 

 the stylus arm jammed by the pen lifter bar in 

 the high-temperature position. If another BT is 

 aboard, use it, and turn in the damaged instru- 

 ment for adjustment. If a spare is unavailable, 

 gently lift the stylus arm from the pen lifter 

 bar and let the arm swing back toward the low- 

 temperature side. 



The temperature calibration henceforth will 

 be in error as a result of deformation of the 

 Bourdon. This information must be recorded on 

 the bathythermograph logsheet. The BT logsheets 



are special sheets, issuedby the National Oceano- 

 graphic Data Center, for recording the informa- 

 tion obtained by lowering the BT. These logsheets 

 are discussed later in this chapter. 



When a BT has been damaged, turn in the 

 instrument to the nearest repair facility at the 

 first opportunity. The BT repair facilities are 

 located at the San Francisco, Pearl Harbor, and 

 Boston Naval Shipyards. 



BT TOWING EQUIPMENT 



Towing equipment required to operate the 

 bathythermograph is described in the following 

 list. 



1. Hoist: The hoist has a drum with a capacity 

 of 3000 feet of cable, an electric motor with con- 

 trols and reduction gears, a control lever for 



71,75 

 Figure 5-5. — BT towing equipment. 



65 



