Furuno FR-1500 Operator's Manual page 104

DBS - Depth below sea surface
$--DBS,x,x,f,x,x,M,x,x,F*hh<CR><LF>
Depth (feet) *
* Not used
DBK - Depth below keel
DBT - Depth below transducer
Water depth referenced to the transducer.
$--DBT, x.x, f, x.x, M, x.x, F*hh<CR><LF>
Water depth, feet *
* Not used
DPT - Depth
IMO Resolution A.224 (VII). Water depth relative to the transducer and offset of the measuring
transducer. Positive offset numbers provide the distance from the transducer to the waterline.
Negative offset numbers provide the distance from the transducer to the part of the keel of interest.
$--DPT, x.x, x.x*hh<CR><LF>
Offset from transducer, in meters = distance from transducer to water-line
Water depth relative to the transducer, in meters
* Not used
Checksum
Depth (fathoms) *
Depth (meters)
Checksum
Water depth, fathoms *
Water depth, m
Checksum
-8.4-