ComNav P4 Installation and Operation Getting Started
Document PN 29010100 V1r0 - 113 -
Compass Setup – On the Water
The final steps of compass setup should normally be performed only after all other
installation and
setup procedures for the autopilot system are completed, so that all net
electrical and
magnetic effects of the installation on the compass(es) are taken into
account.
First you must compensate the compass(es) for Magnetic Deviation (in the P4 Autopilot,
Magnetic Deviation compensation of Fluxgate Compasses, and only corrects for Hard-
Iron effects. Soft-Iron effects are not corrected for).
Next, you may need
to calibrate each compass (IE; correct for any inherent constant
directional offset in each). In relatively calm conditions, you will then need to take your
vessel out into open water (the
sea, a lake, a river, etc.) for real world calibration and
testing.
It is important for you to have sufficient on-water space to put the boat through a series of
fairly slow and wide circle turns, and to run the boat for several minutes on a straight track at
various
headings, without encountering obstacles, other marine traffic, etc. You should also
avoid
areas around bridges, underwater power lines, and pipelines, as these can affect your
compass(es).
Caution! Be sure to maintain a proper lookout for any other vessels and hazards,
while doing
any of the circle turns and manoeuvres described below.
During any of these procedures, the INVALID HEADING alarm may occur. You can
cancel
it by pressing the ENTER button, or simply leave it active.
NOTE: some of the steps performed here require you to be familiar with the STANDBY
mode and menu of the autopilot.
Compensation for Magnetic Deviation
The procedure you use to compensate your compass(es) depends on the type(s) of
compasses that you have installed. Some procedural elements are all the same:
You can take as long as you like to start the turns required to compensate any of the
compasses requiring it, but once the SPU detects that you have you have started the
turns,
you have ~6 minutes to complete enough turns, before a “Failed …” screen
appears.
You may choose to do the turns either to Port or to Starboard. It doesn't matter
which
way, as long as you do not reverse direction during the compensation step.
Boat speed matters only in that it should be sufficient to hold a constant rate of turn
(
of
about 2 to 3 degrees per second), meaning that the full circle should take between 2 and 3
minutes. As well, conditions should be calm enough that you can make smooth, steady
turns
, without rough seas altering the results.
Magnetic Compass Sensor
ComNav strongly recommends that a professional compass adjuster compensate Magnetic
Compasses. The Sensor itself does not require compensation, only calibration.
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