Instruction Manual
20220653 / Rev. C 5
1 INTRODUCTION
The compass or heading sensor is the most vital component in an
autopilot system.
Therefore, great care should be taken when choosing compass
type and finding a good mounting location.
Not only should the compass be of good quality, it is even more
important that a good mounting location is found.
Last, but not least, the compass must have calibration /
compensation facilities.
The best autopilot steering is obtained with a compensated
compass!
Of all complaints or problems about autopilots, 70-80% of the
trouble can one way or the other be attributed to poor
performance of the magnetic heading sensor.
Typical complaints are;
• “My boat doesn’t steer going North.”
• “I can steer on all headings but one or two.
• “In a following sea my vessel is wild, the autopilot will not
steer it.”
• “It steers fine when the sea is calm, but not when it’s rough.”
The autopilot compass senses the earth’s magnetic field to
determine whether or not the vessel is actually turning, thereby
producing a heading error signal. If the field is distorted by local
magnetic influence, then the compass cannot accurately measure
the degree of turn.
If the compass does not present a stable reference, no amount of
subsequent electronic processing can compensate for the signal
errors.
The compass will be unable to detect a change in course on some
headings, where on other headings a minor turn will cause the
compass to show a large course change, thereby putting on
excess corrective rudder.
Carefully study chapter 4 of this manual prior to installing a
magnetic heading sensor for your autopilot.
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