Masters and Officers should be aware that portable electrical equipment (e.g. radios and tape recorders) or items made of steel can affect the performance of a compass and must ensure that such items are kept away from the compass position. A compass deviation card should be prepared each time the compass is adjusted. Separate deviation cards should be prepared for the standard compass and the transmitting magnetic compass repeater, if fitted (Not required for TMC if attached to the Magnetic Compass). The gyro compass (or compasses) should be checked to ensure that the speed and latitude corrections are properly applied. Gyro maintenance records should be reviewed to confirm that the gyro(s) are operating satisfactorily. This can be done either manually or by automatic input from GPS/Logs. Each of the gyro repeaters, including those that may be fitted in the emergency steering position and the engine control room must be synchronized. Where two gyros are fitted, a change-over device must be fitted, and change-over procedures must be posted. Magnetic and gyro compass errors should be checked and recorded each watch, where possible, using either azimuth or transit bearings. A deviation card for the magnetic compass should be maintained and be available to the Bridge Team. (5th edition BPG 4.3.4) The error of the gyro should be determined by external observations – celestial bearings, transits etc. and the gyro and magnetic compass headings then compared to determine the magnetic compass error. Where a gyro repeater is used to take a bearing, an accurate comparison between the repeater and the master gyro should be made. When compass errors cannot be taken it is not necessary to state this in the compass error book. The previous record completed by a qualified compass adjuster should be retained to prove that adjustment has not been required in the intervening period. A comparison between the magnetic and gyro headings should be made at each substantial course alteration and once each watch. Details must be recorded in the Deck Log Book. Some Administrations require compass errors to be recorded in the Deck Log Book rather than a separate Compass Error Book. The Magnetic compass errors recorded in the compass error book should broadly agree with the deviation card. The Magnetic compass deviation may be excessive at the time of inspection due to the presence of external metal structures such as loading arms, gangway towers etc.