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Safety distance standard for magnetic compass deck mounting

4 General

4.1 Compass positions The specifications governing the minimum distances of a compass from magnetic material take into consideration the accuracy required of that compass for normal navigation. The magnetic compass shall be positioned in the centre of the ship. Only in exceptional cases is a deviation from this requirement acceptable.

4.2 Safe distances Safe distances from the magnetic compass are prescribed for magnetic and electrical equipment. They are defined as the minimum distances considered necessary for any of these items in order to eliminate or greatly reduce the magnetic fields acting on the magnetic compass and causing it to deviate.

4.3 Accuracy of magnetic compasses The reliability and accuracy of magnetic compasses are dependent to a great extent on their position in the ship and on the proximity of magnetic and electrical equipment in relation to that position. Varying degrees of reliability and accuracy are, however, permitted, dependent on the function the compass has to perform and the overall length of the ship in which it is installed.


4.4 Functions of magnetic compasses

4.4.1 Magnetic compasses are classified according to the functions they are intended to perform in ships. In the following description of the function of the standard magnetic compass, no account has been taken of the possible fitting of one or more gyro-compasses in the ship. The fitting of a gyro-compass shall not be taken as a reason for reducing in any way the accuracy to be expected from the ship’s standard magnetic compass, which is the primary means of navigating a ship.

4.4.2 The standard magnetic compass shall be sited in the vicinity of the position from which the ship is ordinarily navigated and the view of the horizon from this position shall be as uninterrupted as possible, for the purpose of taking bearings. In the sector from right ahead to 115° on either side, the view of the horizon may be interrupted only by masts, derrick posts, cranes and similar obstructions.

4.4.3 If the standard compass sited on the wheelhouse top is of the projector or reflector type, thus providing the heading information clearly readable by the helmsman at the main steering position, it also acts as the steering compass.

4.4.4 An example of a stand-by steering compass is a steering compass fitted in a ship’s wheelhouse where the reflected or projected image of the standard compass is available and principally used for steering. An emergency compass is one fitted for the purpose of conning or steering the ship after damage or breakdown of all other means of doing so.

4.4.5 Magnetic control sensors are not used for any of the purposes defined in 4.4.2, 4.4.3 and 4.4.4. 5 Minimum distance requirements concerning the ship’s structure 5.1 The standard compass shall be so positioned that it complies with the minimum distance requirements for magnetic material which may be regarded as part of the ship’s structure, as indicated in Figure 1. Any magnetic material in the vicinity of the compass but outside the minimum distances (see Figure 1) should be disposed symmetrically relative to the compass.

compass install




Magnetic compass CGT 165 Projection magnetic compass 500 1


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