Chapter 5— BATHYTHERMOGRAPH 



XBT is more accurate and has a greater depth 

 range than the conventional BT. Moreover, its 

 use removes speed restrictions on the ship. 

 Readings can be obtained at speeds to 30 knots. 



COMPONENTS 



The expendable bathythermograph system is 

 composed of a sensor probe, a cannister, a 

 laiuich mechanism, and a temperature-depth re- 

 corder. The expendable portion of the system, 

 consisting of the cannister and the probe, is 

 seen in figure 5-24, and figure 5-25. The probe 



weighs about 1 pound and is spin stabilized. It 

 contains a thermistor, which senses tempera- 

 ture changes, and a reel of special wire. The 

 cannister also contains a reel of wire, and 

 holds the probe. The launcher is essentially 

 a tube for holding the cannister. It can be 

 installed to provide through-the-hull launciiing 

 of the probe, eliminating the necessity for sonar 

 personnel to be on deck in rough weather. The 

 recorder (fig, 5-26) plots a track on a strip 

 chart of temperature versus depth in real time. 

 The strip chart is synchronized to the probe's 

 rate of descent. 



Figure 5-27. 



71.120 

 Recorder chart. 



89 



