An autopilot performing automatic track-keeping functions and its alarm outputs should always be closely monitored.

The ability of the autopilot closely to follow a planned track will depend upon the accuracy of the XTE information sent to the autopilot from the navigation system (see sections 4.8.2 and 4.8.3).

4.3.3 Off-course alarm

As part of the steering control system there should be an off-course alarm facility to warn the OOW when the ship excessively deviates from its course. The alarm should be in use at all times that the autopilot is in operation.

The use of the off-course alarm does not relieve the OOW from frequently checking the course that is being steered.

Non-activation of the off-course alarm will not always mean that the ship is maintaining its planned track. The ship may be moved off its track by wind and currents even though the heading remains unchanged.

4.4 Compass system

4.4.1Magnetic 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.

4.4.2Gyro 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.