Installing the magnetic steering compass.
Reference ISO 25862:2009.
It is very important that the following guidelines are followed, in order that the magnetic steering compass performs correctly. Unless these guidelines are followed
the compass can become unusable.
1. If the “Safe Distance” is given for any electrical/electronic equipment in the area where the compass is to be installed,
the magnetic compass should be installed outside that distance. Alternatively, the equipment should be installed at a greater distance than the “Safe Distance” away from the compass.
Electrical wiring carrying DC current should be arranged in bi-polar fashion so that the magnetic fields generated by the two currents compensate each other. This can be achieved by forming a twisted pair. This includes the compass light feed wires which are
supplied as a twisted pair. They should be left as such and NOT untwisted.
3. Entertainment speakers cause a particular problem and should be installed more than 3 metres
from the compass, unless the Safe Distance is known. If the Safe Distance is known this will provide the necessary guidance.
4. Other electrical/electronic equipment where the
Safe Distance is not known should be installed more than 3 metres away from the magnetic compass.
5. Aligning the compass with the fore and aft line: Measure
the distance between the centre line of the vessel and the centre of the compass bowl. On the foredeck; repeat this measurement from the centreline to the push-pit rail and mark with tape.
the compass in position with the shadow pin and lubber line of the compass and the tape mark all in line (transit), this will ensure that the compass is parallel with the fore and aft line of the vessel. Mark the position of the compass carefully and drill
the mounting holes. Screw down.
(Ideally, it is preferable to drill just one mounting hole and secure the compass with one screw. The other holes are drilled and screws inserted after the compass
is adjusted and the alignment checked)
Note: The fluxgate compass which if fitted, feeds the autopilot and other equipment, is a magnetic compass and can suffer from deviation caused by the
magnetism of nearby objects. The manufacturers installation manuals should give the necessary guidance on the siting of the fluxgate. However, you should consider the location of this compass in relation to the electrical and electronic equipment onboard.
This memo produced by our own
Captain MIKE ROSSITER, COMPASS ADJUSTER, MASTER UNLIMTED.