The Expendable Bathythermograph (XBT) has been used by oceanographers
for many years to obtain information on the temperature structure of
the ocean to depths of up to 1800 meters. The XBT, shown in
Figure 1,
is a probe which is dropped from a ship and measures the temperature
as it falls through the water. Two very small wires transmit the
temperature data to the ship where it is recorded for later analysis.
The probe is designed to fall at a constant rate, so that the depth of
the probe can be inferred from the time since it was launched. By
plotting temperature as a function of depth, the scientists can get a
picture of the temperature profile of the water.
On many projects it is necessary to deploy XBTs on a 24 hour schedule
as the ship steams along its course. Since a trained operator is
needed to operate the system, it was necessary to send two people so
that operations could be conducted around the clock. To reduce the
workload, AOML has designed and is now testing an automated XBT
launcher that will allow this work to be conducted by only one person.
Eventually, it is hoped, the ship's crew will be able to operate the
system and no operators will have to accompany the system.
A photograph of the XBT Autolauncher is shown in
Figure 2. Up to six
probes can be preloaded and then deployed at predetermined launch
times or positions. All operational functions and data recording are
controlled by a personal computer. Presently the system is being used
on a Mexican registered container ship that steams between ports in
the Mediterranean Sea and Veracruz, Mexico.