Gyrocompass

A gyrocompass is a north-seeking heading reference that uses a spinning rotor and Earth’s rotation to find true north, independent of the magnetic field. SOLAS Chapter V Regulation 19 requires it on all ships of 500 GT and above, together with a heading repeater at the emergency steering position and a bearing repeater covering 360 degrees. It feeds true heading to the radar, ARPA, AIS, ECDIS, and the autopilot, and is unaffected by magnetic deviation or local anomalies. It carries a small speed and latitude error that is corrected automatically on modern units. The magnetic compass remains the required independent backup.