All ships of 500 gross tonnage and upwards shall have:

• a gyro compass, or other means, to determine and display their heading by shipborne nonmagnetic means, being clearly readable by the helmsman at the main steering position. These means shall also transmit heading information for input to the 9 GHz Radar, AIS, an automatic tracking;
• a gyro compass heading repeater, or other means, to supply heading information visually at the emergency steering position if provided;
• a gyro compass bearing repeater, or other means, to take bearings, over an arc of the horizon of 360º, using the gyro compass or other means. However ships less than 1,600 gross tonnage shall be fitted with such means as far as possible;

The “true heading” is the horizontal angle between the vertical plane passing through the true meridian and the vertical plane passing through the ship’s fore and aft datum line. It is measured from true north (000°) clockwise through 360°. The compass is said to be “settled” if any three readings taken at intervals of thirty minutes, when the compass is on a level and stationary base, are within a band 0,7°.