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2. The fishfinder won’t turn off:
The fishfinder may have been wired for
Auto power. In this case, the fishfinder
cannot be turned off while the ignition
power is on. (See Auto power wiring in
section 6-5 Wiring options.)
3. The fishfinder operates erratically:
a) Check that the transducer does not have
debris (e.g. weed, plastic bag) caught
around it.
b) The transducer may have been damaged
during launching, running aground or while
underway with debris etc. If the transducer
has been impacted, it may have been kicked
up on the bracket. If it is not physically
damaged, reset the transducer back to
its original position. (See the Transom
Transducer Installation Guide.)
c) When the transducer is less that 2 ft. (0.6 m)
from the bottom, the depth readings may
become inconsistent and erratic.
d) Manual Gain may be set too low, which may
cause weak bottom echo or no fish signals. If
in Manual Gain, try increasing the Gain.
e) Ensure the back of the bottom surface of
the transducer is slightly lower than the
front and the front is as deep in the water as
possible in order to minimize the generation
of bubbles through cavitation. (See the
Transom Transducers Installation Guide.)
f) Check the transducer and power cable
connectors at the back of the display unit
are securely plugged in and the collars are
locked in place. The collars must be secure
for watertight connection.
g) Inspect the power cable from end to end
for damage such as cuts, breaks, squashed
or trapped sections.
h) Ensure there is not another fishfinder
or depth sounder turned on, which may
interfere with this fishfinder.
i) Electrical noise from the boat’s engine
or an accessory may be interfering with
the transducer(s) and/or the Navman
fishfinder. This may cause the fishfinder
to automatically decrease the Gain unless
using Manual Gain.
The fishfinder thus eliminates weaker
signals such as fish or even the bottom
from the display. This may be checked
by switching off other instruments,
accessories (e.g. bilge pump) and the motor
until the offending device is located. To
stop problems from electrical noise, try:
- re-routing the power and transducer
cable(s) away from the boat’s other
electrical wiring.
- routing the display unit’s power cable
directly to the battery with an in-line
fuse.
4. Bottom is not displayed:
a) The fishfinder may have Manual Range
selected and the depth may be outside the
range value selected. Either change the
fishfinder to Auto Range or select another
depth range (see section 4-5 Range).
b) The depth may be outside the fishfinder’s
range. While in Auto Range, the display unit
will display “--.-” to indicate that there is no
bottom detected. A display of the bottom
should reappear when in shallower water.
5. The bottom is displayed too far up
the screen:
The fishfinder may have Manual Range
selected and the selected Range value is
too high for the depth. Either change the
fishfinder to Auto Range or select another
depth range (see section 4-5 Range).
6. Bottom echo disappears or erratic
digital reading while the boat is moving:
a) Ensure the back of the bottom surface
of the transducer is slightly lower than
the front and the front is as deep in the
water as possible in order to minimise the
generation of bubbles through cavitation.
(See the Transom Transducers Installation
Guide, for more information.)
b) The transducer may be in turbulent water.
Air bubbles in the water disrupt the echoes
returned, interfering with the fishfinder’s
ability to find the bottom or other targets.
This often happens when the boat is
reversed. The transducer must be mounted
in a smooth flow of water in order for the
fishfinder to work at all boat speeds.
c) Electrical noise from the boat’s motor can
interfere with the fishfinder. Try some
suppression spark plugs.
FISH 4432/4433 Installation and Operation Manual 36
NAVMAN