This International Standard specifies the installation in ships of magnetic compasses and binnacles complying with the requirements of ISO xxxx magnetic compasses and binnacles of Class A and B.

　

In addition, it covers magnetic control elements used in navigational aids.

　

It should be noted that this International Standard is established only for general purposes. It is not necessarily applicable to all sea-going ships.

　

For the purposes of this International Standard the terms and definitions given in ISO 1069 and the following apply.

　

sensor using the geomagnetic field for feeding an automatic heading-control system, or controlling an off-course alarm unit, or feeding other devices

　

distance measured between the nearest point of the item concerned and the centre of the compass, as determined in annex A

　

distance measured between the nearest point of magnetic material which is part of the ship's structure and the centre of the compass, shown in Diagram 1.

　

　

　

　

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.

　

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.

　

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.

　

3.4.1 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.

　

3.4.2 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.

　

3.4.3 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.

　

3.4.4 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.

　

3.4.5 Magnetic control sensors are not used for any of the purposes defined in 4.4.2, 4.4.3 and 4.4.4.

　

4.1 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.

　

For the standard compass, the distance from the deck below the compass may be reduced to a minimum of 1 m, provided that the other minimum distances according to Figure 1 are kept.

　

If there is only one magnetic compass installed on the ship, this compass shall fulfil the requirements concerning the minimum distances and the safe distances as laid down for the standard magnetic compass in this International Standard.

　

It is emphasized that these distances are minimum permissible distances and should prove satisfactory in the majority of ships. Special cases will, however, arise, where the masses of iron in the vicinity of the compass are such that the compass does not work satisfactorily and, in these cases, the distances should of necessity be increased.

　

4.2 For steering compasses, the minimum distances may be reduced to 65 % of those required for the standard compass.

For steering compasses, the distance from the deck below the compass may be reduced to 1.0 m provided the distance from the extremities of iron decks, bulkheads and girders is not less than 65 % of the distances required for the standard compass.

　

4.3 For stand - by steering compasses and magnetic control elements, the distances may be reduced to 50 % of those required for the standard compass, provided that no distance is less than 1,0 m

　

4.4 For emergency compasses (if fitted), the minimum distance is 1,0 m.

　

4.5 Items which are permanently fixed to the ship's structure shall be treated as part of the latter.

　

4.6 Moveable magnetic parts in the vicinity of the steering compass, e.g. the steering gear, shall not influence the indication of such a compass.

　

4.7 The standard compass and the steering compass shall not be placed in a wheelhouse completely constructed of magnetic material. If the wheelhouse is partly constructed of magnetic material, the magnetic parts should be disposed symmetrically relative to the compass.

　

5.1 Magnetic and electrical equipment and cables carrying direct current close to a magnetic compass may produce a deviation of that compass.

　

5.1.1 In order that the removal or replacement of any item of equipment will not introduce any unacceptable deviation, such an item shall not be placed closer to the compass than its safe distance. The safe distance for any item shall be determined by the method described in annex B. Clips and other components in the vicinity of magnetic compasses shall be of non - magnetic material.

　

5.1.2 Electric wiring carrying direct current, other than coils used for compass correction, within 5 m of magnetic compasses, shall be arranged bipolarly so that the magnetic fields generated by the two opposite currents compensate each other.

　

5.2 Manufacturers of magnetic and electrical equipment shall arrange for the safe distances of such equipment likely to be placed in the vicinity of the magnetic compass to be determined by the method described in annex B. The manufacturer shall mark each item of portable equipment with its safe distance.

For fixed equipment, the manufacturer may mark the equipment or specify the safe distance in the equipment manual.

　

5.3 Items for which the safe distance is not known shall not be placed nearer than 5 m to the standard compass or the steering compass. This distance may, however, be reduced to 3 m for standard compasses and steering compasses in ships intended for restricted service only.

　

5.4 When determining the safe distance of large items of equipment such as radar sets, it is sometimes permissible to make a distinction between those items which are readily interchangeable and those which consist of large masses, the exchange of which would entail a considerable amount of work. In such cases, the safe distance of any item which is readily interchangeable is determined in accordance with 5.1.1 so that it may be removed or exchanged without appreciably affecting the compass. The remainder of the equipment, comprising the "large masses", is treated as a part of the ship's structure (see 5.5) and, if it is removed or exchanged, the compass affected shall be readjusted.

　

5.5 Magnetic compasses shall not be placed nearer than 2 m to one another or to magnetic control sensors. In ships of less than 60 m overall length, this distance may be reduced to 1,8m.

　

The safe distance for any item of equipment shall be determined by the method described below. Test each item in the position and attitude relative to the compass or magnetometer at which the error produced at the compass would be a maximum, provided the item can be fitted in this way.

　

The safe distance of any item is defined as the distance measured between the nearest point of the item and the centre of the compass or magnetometer at which it will not produce a deviation

　

Test each item