Basic Operation

Figure 2-2.—MX-8577/SSQ-61 bathythermograph through-the-hull launcher. bathythermograph probe (fig. 2-3), equipment components are all interchangeable. The standard probe is manufactured by the Sippican Corporation and is widely known as the T-4 probe, rather than as the OC- 14/SSQ-56 probe. An expendable bathythermograph probe is popularly called an XBT. An XBT consists of a probe with a thermistor installed in the nose and a canister. The probe descends at a known rate through the water, and the recorder converts the thermistor’s electrical resistance (and descent time) into depth and temperature units. The thermistor is connected by a fine wire to contact pins mounted in the end of the canister, which is retained in the launcher during the measurement. When the measurement is completed, the wire breaks as the probe descends beyond the maximum depth of the probe. The canister is then removed from the launcher and discarded. A cable from the launcher connects to the recorder. Specific operation and maintenance instructions for each system are contained in the manualscited in the reference list. All recorders except the original RO-326 have changeable chart drive gears and an internal selector switch that allows operation with different types of probes. All systems most commonly use the T-4 probe. Basic Operation followed: An XBT observation may be conducted by one person, but it is much easier using two people with sound-powered telephones. One person should be stationed at the recorder (identified as “A”) and the second person at the launcher (identified as "B"). With two people (A and B), the following sequence must be " A " : " B " : " B " : " A " : Turns on power at the recorder. Opens launcher ball valve and breech (through-the-hull launchers). Removes end cap from XBT, loads probe canister, and locks the breech. Verifies automatic start sequence of recorder and chart alignment. 2-4