Gyrocompass

A gyrocompass is a type of non-magnetic compass which is based on a fast-spinning disc and the rotation of the Earth (or another planetary body if used elsewhere in the universe) to find geographical direction automatically. A gyrocompass makes use of one of the seven fundamental ways to determine the heading of a vehicle. A gyroscope is an essential component of a gyrocompass, but they are different devices; a gyrocompass is built to use the effect of gyroscopic precession, which is a distinctive aspect of the general gyroscopic effect. Gyrocompasses, such as the fibre optic gyrocompass are widely used to provide a heading for navigation on ships. This is because they have two significant advantages over magnetic compasses:

• they find true north as determined by the axis of the Earth's rotation, which is different from, and navigationally more useful than, magnetic north, and
• they have a greater degree of accuracy because they are unaffected by ferromagnetic materials, such as in a ship's steel hull, which distort the magnetic field.

Aircraft commonly use gyroscopic instruments (but not a gyrocompass) for navigation and altitude monitoring; for details, see flight instruments (specifically the heading indicator) and gyroscopic autopilot.