Fluxgate compass

The basic fluxgate compass is a simple electromagnetic device that employs two or more small coils of wire around a core of highly permeable magnetic material, to directly sense the direction of the horizontal component of the Earth's magnetic field.

To avoid inaccuracies created by the vertical component of the field, the fluxgate array must be kept as flat as possible by mounting it on gimbals or using a fluid suspension system.

All the same, inertial errors are inevitable when the vessel is turning sharply or being tossed about by rough seas.

To ensure directional readings that are adequately stable, marine fluxgate compasses always incorporate either fluid or electronic damping.

It can also be used to correct for the roll- and heel-induced errors that often plague fluxgate compasses installed on steel vessels.