malfunctions on both types of recorders appear
basically the same. See table 2-1 for a listing of
common malfunctions and corrective actions.
EVALUATION OF ANOMALOUS
Anomalous features detected in a recorder trace
from either the AN/SSQ-56 (series) recorders or the
AN/BQH-7(A) recorder may invalidate the
observation. Another probe should be launched after
the cause of the problem is identified and corrected.
Although somewhat dated, the Naval Oceanographic
Office Reference Publication, RP 21, Guide To
Common Shipboard Expendable Bathythermograph
(SXBT) Recording Malfunctions, identifies and
explains the cause of many trace anomalies. This
publication should be thoroughly reviewed by every
Obvious equipment malfunctions normally occur
in less than 10 percent of all launches. However,
improper handling of the probes can cause a greater
number of failures than normal. Rough handling or
improper storage of probes can cause the flattening or
compaction of the wire in the probe and canister spools,
abrasion of the insulation on the wire, or tangles in the
wire. These failures can be significantly reduced by
storing the probes away from extreme temperatures and
humidity. Probes should always be maintained in a
vertical position with the protective cap (weighted end
of probe) down.
When conducting an observation, the operator
should be aware of the expected thermal characteristics
in the area. Large variations in thermal structure is quite
common in the vicinity of ocean fronts and eddies. If
anomalous features are detected in the trace that cannot
be attributed to a malfunction or to an expected thermal
feature, a second probe should be launched.
OF TEMPERATURE AND
The evaluation of the temperature curve is a simple,
The observer must select
significant levels on the temperature curve so that the
entire curve may be reconstructed by connecting the
selected points with straight lines. Temperatures are
read to the nearest tenth of a degree (°C or °F) and to the
nearest meter or tens of feet of depth.
There are three terms that are used to describe the
gradient (or trend) of the temperature trace on a
The first term is positive
temperature gradient, and is defined as an increase in
water temperature with depth. The next term, negative
temperature gradient, is the opposite of positive
temperature gradient, and is defined as a decrease in
water temperature with depth. The last term is
isothermal gradient. It is defined as no change in water
Table 2-1.Common Malfunctions in Bathythermograph Recordings
Stylus makes erratic excursions to
Leak from probe wire to salt water.
Launch new XBT.
the right of the chart paper.
Stylus makes excursion all the way Complete wire breakdown.
Launch new XBT,
to left of chart paper and remains
Stylus makes erratic excursions to Contamination, such as excessive Breech pins should be wiped
the left of chart paper.
salt water, between breech and
thoroughly and new XBT inserted.
Recorder completely inactive,
POWER switch to OFF or power
indicators not illuminated.
cord unplugged. Fuse blown.
INTERLOCK switch open.
HF radio transmission affect Electromagnetic interference.