GYROCOMPASS

A gyrocompass­ (less often spelled gyro-compass­ or gyro compass​) is a type of non-magnetic compass which is based on a fast-spinning disc and rotation of our planet to automatically find geographical direction.
Although one important components of a gyrocompass is a gyroscope, these are not the same devices; a gyrocompass is built to use the effect of gyroscopic precession, which is a distinctive aspect of the general gyroscopic effect. Gyrocompasses are widely used for navigation on ships, because they have two significant advantages over magnetic compass:

• they find true north as determined by Earth's rotation, which is different from, and navigationally more useful than, magnetic north.