What is a Magnetic Compass, its principle, types and errors?

Monitoring Compass Performance

Compass performance should be monitored by frequently recording deviations in the compass deviation book. Compass errors should be determined after every large alteration of course, and at least once every watch when there have been no major course alterations. Checking the compass deviation regularly may show the need for repair, testing or adjustment. In addition, compasses should be inspected occasionally by a competent officer or compass adjuster.

 Can we use magnetic compass at the pole?

No, we cannot use magnetic compass at pole  because at the pole the directive force is Zero. At the equator the magnetic compass is more accurate.

How many type of liquid used/ added in magnetic compass?

Two types of liquid use in magnetic compass:

  1. Mixture of distilled water and ethyl alcohol , Two part of distilled water and one parts of ethyl alcohol providing a fluid with low viscosity and small coefficient of expansion.
    • Distilled water will reduce evaporation in worm tropical climate.
    • Alcohol will reduce frizzing point of mixture in cold weather.
  2. Oily liquid
    • Provided additional flotation for card.
    • Lubricate the pivot.
    • Reduce motion on the card.
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About the author

Amit Sharma

Graduated from M.E.R.I. Mumbai (Mumbai University), After a brief sailing founded this website with the idea to bring the maritime education online which must be free and available for all at all times and to find basic solutions that are of extreme importance to a seafarer by our innovative ideas.


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