The direction of the fore and aft and thwartship corrector magnets shall not deviate more than 2°from the direction of the outer gimbal axis or its perpendicular respectively, and shall be within 2°of the horizontal.

　

The holes or grooves for the fore and aft and for the thwartship corrector magnets, when of the conventional type, shall be mounted in such a manner and be of such a size that the mid-point of the appropriate magnets when in place lies within 5 mm of the vertical planes passing through a thwartship and the fore and aft gimbal axes respectively.

　

　

　

(ISO 449) 6.1.2.3

Binnacles shall contain a device for correcting the deviation due to the horizontal components of the ship's permanent magnetism. This device shall be capable of correcting a coefficient B of up to at least (720/H)°and a coefficient C of up to at least (720/H)°, H being as defined in 5.3.4.

　

Provision shall be made in binnacles so that no magnets of the correcting system come so close to the directional system as to distort the field and on any course even when there may be a heel or pitch of 15°produce a deviation of more than (20/H)°in case of type A1(40/H)°case of type A2.

The amount of deviation that can be corrected by the corrector magnets can be measured by placing the maximum number of correcting magnets in the thwartship direction setting the compass on the corrector stand in its binnacle and aligning it on north or south. The angular difference between the stand alignment and the magnetic north or south indicates the correcting power of the magnets. This should be repeated on east or west using the fore and aft magnets.

　

The distance of the magnets from the directional element in a type A1 binnacle shall be measured.

　

In a type A2 binnacle, the compass in its binnacle is placed on the test stand and aligned on north or south. An external magnetic force sufficiently far away to create a reasonably even field in the vicinity of the directional element is applied until a deviation of (720/H)°is obtained. This deviation is then corrected by the magnets in the binnacle. The binnacle is tilted 15°. The resulting deviation shall not exceed (40/H)°.

Repeat on east and/or west.

　

Binnacles shall be provided with a device for compensating the horizontal magnetic fields due to induction caused by the horizontal component of the earth's magnetic field in the soft iron in a ship.

This device shall be capable of correcting a coefficient D of up to 10°in the case of A1, and 7°in the case of A2.

When binnacles are vertical and compensation is effected by spheres, the centre of the device shall not be further than 15 mm from the horizontal plane passing through the magnetic element of the directional system.

　

The axes of the correctors shall be fitted in such a way that they can be moved in the direction of their axis along a binnacle diameter, which shall not deviate more than 2°from the direction of the athwartship gimbal axis.

　

Alignment errors can be checked by means of the card or verge ring graduations.

　

The amount of deviation that can be corrected can be checked by placing the compass and binnacle on a test stand on a quadrantal course with and without the correctors in position.

　

The height of the correctors relative to the directional element can be checked by measuring the distance of the device centre from the inner gimbal axis and applying the information provided by the manufacturer.

　

　

(ISO 2269, 4.2.4.4) With a type A1 binnacle, a Flinders' bar shall be provided. With type A2 binnacles, a Flinders' bar may be provided where required.

When a Flinders' bar is used, it may be hollow, provided the diameter of the hole does not exceed 40% of the diameter of the bar.

When binnacles are vertical, the magnetic pole of the device shall lie in the same horizontal plane as the centres of the magnets of the directional system. When a Flinders bar is used, its magnetic pole shall be taken at 1/12 of its length from the end.

　

4.3.2.5.2.6 The line connecting the vertical axis of the Flinders's bar to the compass centre shall not deviate more than 2°from the direction of the fore and aft gimbal axis. (ISO 2269 4.2.4.4.1)

　

　

　

4.3.2.6.1 Provision may be made for the fitting of corrector coils to provide compensation, if the ship is fitted with degaussing coils.

　

The binnacle shall contain adequate provision for illuminating the card by means of the ship's electric supply and from an emergency light source. In projector and reflector binnacles. These shall provide a clear image at the helmsman's position. Devices shall be provided for dimming the illumination at both the helmsman's position and the binnacle.

　

The lamps, plugs, sockets, switches, dimmers and wiring, whether energized or not, shall have no perceptible magnetic effect on the compass on any heading.

The examination can be carried out by trial.

　

In compasses of the reflector or projector type, the optical system shall be such that the image of the lubber mark and a sector of the card 15°on either side of the lubber mark shall allow a person with normal vision to read the card both in daylight and artificial light at a distance of 1 m from the periscope tube.

　

Damp heat test, vibration test and corrosion test shall be carried out by the methods of testing and required test results of IEC 60945, and shall meet the requirements.