Northstar FISH 457/467 Installation and Operation Manual 59
b The transducer may be in turbulent water.
Air bubbles in the water disrupt the echoes
returned, interfering with the 457/467’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 457/467 to work
at all boat speeds.
c Electrical noise from the boat’s motor
can interfere with the 457/467. Try some
suppression spark plugs.
3-5 There is a double bottom trace displayed:
a The boat may be in an area that generates
shadows (see section 3-2).
b In shallow water, the echoes may bounce.
Reduce the gain setting (see section 3-6)
and/or reduce the sonar pulse power (see
section 8-2).
c Decrease the Range.
Appendix C - Glossary and navigation data
NavBus - A way of connecting Northstar instruments together to share data (see section 9-8).
NMEA - National Marine Electronics Association.
NMEA 0183 - A standard for interfacing marine electronic devices (see section 9-9).
SBN II- Signal enhancement Bottom recognition Noise rejection.
SmartCraft - A feature of Mercury Marine engines for monitoring engine performance.
Glossary
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