A magnetic compass, which is used to assist in navigation, is an instrument that shows magnetic north. You must apply a correction to determine the direction of true north. The ability to steer a pleasure craft by a compass is useful if land is out of sight, visibility is reduced, or the pleasure craft operator is disoriented.
Mount a compass away from iron, magnets, and electrical wiring and equipment. Practice with your compass and other navigation equipment in good weather. Make sure you know how to use them. This will give you confidence during bad weather.