ComNav P4 Installation and Operation
Document PN 29010100 V1r0 - 45 -
Compasses
ComNav P4 autopilot systems are typically supplied as a complete System Kit, with one of several
types of available compasses; the compass type chosen typically depends on the type and
intended
use of the boat.
a Fluxgate Compass
a Magnetic Compass Sensor (for use with the traditional type of externally-gimballed
magnetic compass, such as the ComNav 5” and 6” Binnacle Compasses)
a Tri-Axis Rate Gyro Compass-SSRC1
a GNSS G2 (or G2B) GPS Compass or other NMEA compass
Refer to the appropriate section below for specific installation instructions for your
Fluxgate or Magnetic
Compass.
NOTE: if you have a Rate Gyro compass, a G2/G2B or other NMEA compass,
please also refer to the
Installation and Operation Manual that came with it.
Compass Deviation
When first installed, some Fluxgate and Magnetic Compasses will exhibit deviation effects. Magnetic
Deviation is an error between the compass reading and the boat’s actual Magnetic
heading. Deviation is a
result of magnetic fields induced in the boat’s hull (especially on steel
boats) as well as by other various
factors. It can also be caused by electromagnetic fields from objects such
as engines, davits, galley
equipment and the like, from the boat’s electrical/electronic
systems and wiring, or even from ordinary
electronic items such as PCs, cell phones, CD/MP3 players and AM/FM radios.
If you have a ComNav Fluxgate Compass, the P4 can electronically compensate for the Hard-Iron
portion of
the Deviation. The compensation procedure is done during the Sea Trials.
If you have a magnetic compass, it will have to be manually compensated for deviation. A
person who
specializes in
professional compass adjustment can (and should) do this job.
If you have a Tri-Axis (SSRC1) Rate Gyro Compass, you can calibrate the compass during the Sea
Trials.
If you are using a fluxgate compass other than a ComNav Fluxgate Compass, or a magnetic
compass
not supplied by ComNav, you should contact the dealer or manufacturer you
purchased it from, for
instructions on how to install it, set it up, and compensate it.
NOTE:
The ComNav and the G2 and G2B GPS Compasses, are not affected by
deviation. Soft-Iron effects
must be dealt with by installing the compass far enough away from sources of deviation.
Caution! Do not permanently install any compasses until Sea Trials are complete. You may have to
relocate the compasses, during the trials.
Common Installation Considerations
Avoid running the cable(s) from any Fluxgate Compass or Magnetic
Sensor, parallel to antenna cables,
AC power, or DC wires/cables carrying
heavy current.
Any excess cable or cables should be individually coiled up, in a suitable location near the
destination.
ComNav recommends that compass sensor cables NOT be shortened
(unless specifically stated
otherwise, in the next sections).
I
nstallation
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