An instrument using either a magnet or a gyroscope for steering or taking navigational bearings.
- Gyrocompass – An electrically-driven gyroscopic disc spinning at extremely high speed which keeps its relative axis in relation to space.
- Magnetic compass – A magnetised needle which points to the magnetic North. Some corrections are needed because the magnetic North is not coincident with the true north and the magnetism of the ship itself has to be neutralized.