Furuno FCV-30 Operator's Manual page 5

CAUTION
Do not transmit when the transducer is
out of water.
The transducer may become damaged.
The picture does not advance when the
picture advance speed is set for
"STOP".
A dangerous situation may result if the
vessel is navigated while monitoring
the depth indication since it is not updated
when the picture is stopped.
Set the gain properly.
No picture appears if the gain setting is
too low, and noise appears when the gain
is too high. If the gain is set improperly,
the depth indication may be wrong,
resulting in a potentially dangerous situation
if the vessel is navigated by monitoring
the depth indication.
Gain too high Proper gain Gain too low
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