The bathythermograph recorder (Figure 1-12-6) mounted on the SENSO/Sonar Operator station above the sonar transmitter, provides permanent-dry electrosensitive strip chart recordings of water temperature, search depth, hydrophone salt water ingress and BITE information. Salt water ingress signals will warn the sonar operator of hydrophone degradation. The BT recorder accepts temperature and depth signals from the receiver and plots them as a temperature versus depth gradient on the chart paper. Located on the front panel are the stylus and magazine with depth and temperature scales, an OFF, LO, HI switch for power control and temperature selection, a six-position CALIBRATE switch and a CHART DIM control.