User manual

The action taken after a zero pressure rate detection depends on the MMP depth, the
current profiling direction, and the shallow or deep error programmed by the operator. In the
mid-water region away from the shallow and deep error windows, a zero pressure rate is
interpreted as an obstacle on the mooring cable. The mid-water obstacle ramming behavior is
triggered in an effort to clear the cable and get past the obstruction. The MMP first backs away
from the obstacle for 30 seconds, then moves forward again, (30 second velocity ramp followed
by normal profile speed). If the ramming behavior is successful the MMP continues the profile.
If the obstruction remains, another zero pressure rate will be detected after 3 minutes and the
ramming behavior is repeated. Ramming is limited to a maximum of five occurrences during any
one profile (battery energy and drive train wear required for 15 minutes of drive wheel slip on the
cable is required to make five detections and additional ramming only adds to the battery
depletion). A sixth zero pressure rate detection terminates the profile. The sensors continue to
log for two minutes before the system stops logging and moves the sensor data to the flash card.
The detections do not have to be at or near the same depth. Each restart is logged in the
engineering data file.
Ramming can be disabled at the discretion of the operator by extending the shallow and
deep errors to cover the full extent of the profiling range.
Shallow Error <H>
Shallow error defines a pressure below (deeper than) the shallow pressure stop. If the
system detects a zero pressure rate while inside the shallow error window on an upward profile,
the system stops profiling. The mid-water obstacle ramming behavior is not triggered. The
shallow error is ignored on downward profiles.
The shallow error allows the operator to compensate for current forced mooring
dynamics and for uncertainty in the actual depth of the bottom. As the mooring leans over in a
current or if the anchor is deeper than expected the shallow bumper may be pulled below the
shallow pressure stop. In these cases the obstacle ramming behavior would be futile. The
shallow error is programmed based on calculations of the dynamic mooring behavior in a range
of anticipated currents and knowledge of the possible depth error. Inside that window a zero
pressure rate is interpreted as the shallow bumper and the ramming behavior is not triggered. The
profile terminates as if the shallow pressure stop had been detected.
The mid-water obstacle ramming behavior can be disabled during upward profiles by
setting the shallow error below (deeper than) the deep pressure.
G-49