B&G Network Depth - Manual (Page 8)

THE DEPTH DATUM - D CAL
The depth datum D CAL is an offset calibration value used
to determine the displayed information reference point. It is
added to the actual measured water depth to display the
depth from the waterline, the depth sensor (transducer) or
the keel/outdrive depth.
The Network DEPTH unit has factory set D CAL of zero,
i.e. the depth is displayed from the transducer. The D CAL
value is displayed in the same units as the depth.
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