Magnetic compass
The magnetic compass is generally fitted above the bridge on the centreline with a periscope so that the compass is readable from the helmsman's position.
Where the magnetic compass is needed to provide heading outputs to other bridge systems, a transmitting magnetic compass (TMC) is fitted. TMC outputs should be corrected for compass error and the TMC should be tested once a week, in clear visibility.
A compass deviation card should be maintained and posted on the bridge. The compass will need to be swung at intervals during the ship's life, and particularly after major steel conversion work to the ship. Caution should be observed when using the magnetic compass on ships that carry magnetic cargoes such as iron and steel.
Compass safe distances are specified on all electrical bridge equipment and provide the minimum distances that equipment can be installed from the magnetic compass.
Gyro compass
It is recommended that the gyro compass should be run continuously. Should a gyro compass stop for any reason, it should be restarted and subsequently checked before use to ensure it has settled and is reading correctly.
Speed and latitude corrections need to be applied to the gyro compass. Where the gyro has no direct speed log or position input, manual corrections will have to be made as required.
Compass errors
As a safeguard against the gyro and gyro repeaters wandering, frequent checks should be made between the magnetic and gyro compasses.
Magnetic and gyro compass errors should be checked and recorded each watch, where possible, using either azimuth or transit bearings.
A record of magnetic and gyro compass courses to steer and compass errors should be maintained and available to the helmsman.
