The BT recorder is utilized to obtain graphs of water temperature versus depth, and is also used to display a warning of salt water ingress into the hydrophone portion of the transducer. Temperature and depth signals obtained from the transducer are processed by the receiver and dome control and applied to the recorder circuits when the recorder SCALE switch is positioned to either LO (25 to 75 degrees Fahrenheit) or HI (45 to 95 degrees Fahrenheit). The recorder drive circuits automatically position the chart pen to record temperature and transducer depth. Scale marks on the chart paper denote the temperature recorded.

The recorder plots temperature on the horizontal scale and depth on the vertical scale. The continuous BT graph provides a recorded display of the temperature gradients. Should the leak detect sensor in the hydrophone become activated by sea water, a signal will be sent to the horizontal (temperature) drive circuits every 3 seconds to create a +25 degree fluctuation above the ambient temperature.