Raymarine C140w User Reference Handbook page 170

Menu Item Description
Depth Offset Offset represents
(waterline) the depth of the
transducer (relative
to the waterline).
Speed Offset Offset applied to the
speed log.
Temperature Offset Offset applied to the
temperature transducer
value.
170
Options
—9.9 to +9.9 feet
0 to 100%
—9.9 to +9.9 °F
C-Series Widescreen user reference