XBT

What it's used for

The Expendable Bathythermograph (XBT) captures temperature data as it sinks through the ocean. It provides a quick and inexpensive means for obtaining data about the temperature of the water column at different depths.

How it works

The XBT is a hand-held device that consists of an expendable probe, a data processing and recording system, and a launcher.

When the XBT probe is launched, the copper wire connecting the probe and launcher unwinds as it descends through the water. Once the electrode in the probe makes contact with the water, temperature data can be transmitted back to the ship's data processing equipment.

Data collected by the XBT can be used in conjunction with other recording equipment - for example, a thermosalinograph - to profile the water column.