This International Standard gives general requirements regarding construction and performance type test and individual test methods for magnetic compasses, binnacles and azimuth reading devices, class A and B. According to the design of the ship, two types of binnacle are specified.

This International Standard applies to liquid-filled magnetic compasses:

- intended for ship's steering purpose in sea navigation according to regulations in force;

- having a direct reading system;

- which may be of the reflecting, projecting or transmitting types. In the context of this International Standard, a magnetic compass is an instrument consisting of a directional system supported by a single pivot inside a bowl which is completely filled with liquid, and which is supported in gimbals inside or outside the bowl. Compasses without gimbals are also covered by this International Standard. The requirements relating to gimbals do not apply to such compasses.

　

All ships applied SOLAS (the ships of 150 gross tonnage and upwards engaged on international voyages and the ships of 500 gross tonnage and upwards not engaged on international voyages) shall be fitted the Class A magnetic compass. All ships not applied SOLAS shall be fitted the Class A or Class B magnetic compass.

　

This International Standard, otherwise stated, applies to all magnetic compasses, and does not apply to:

　

　

For the purposes of this International Standard, the definitions given in ISO 1069 apply.

A magnetic compass for determine the ship's heading and display the reading at the main steering position.

　

　

　

Unless otherwise stated, all tests shall be carried out at a temperature of 20℃±3℃, and H is to be understood as the horizontal component of the magnetic flux density, in microtesla (μT), at the place of examination.

　

Devices which have passed the type-tests or the individual tests and comply with the requirements shall be so certified in the language of the test authority and in English.

　

Each type-test certificate is valid exclusively for the model tested. In case of alterations or technical improvements which affect its compliance with this standard, the model shall be given a new identification number or mark and the type-test repeated. All alterations shall be submitted to the original test authority who will decide whether a new type-test is necessary (see annexes A, B and C).

　

Copies of the certificate shall be issued on demand. They shall explicitly be marked "copy".

　

Acceptance of type-test certificates and individual test certificates between countries will be a matter for mutual agreement.

　

Testing shall be carried out on all compasses, with or without a transmitting system. All compasses, other than those compasses without gimbals which are used as steering compasses only, shall be tested with their gimbal rings and outer gimbal bearings.

　

The manufacturer shall produce a written statement for magnetic compasses covering those requirements which cannot be ascertained during a type-test (see annex A). The statement shall include the following points:

　

a) that the magnets used in the directional systems of magnetic compasses are of a suitable magnetic material having a high remanence and coercivity of at least 18 kA/m. All other materials used in magnetic compasses, other than transmitting compasses, are of non-magnetic material (ISO449,5.1.1) (ISO613,4.1.1)

　

b) that the paint inside the compass is of good quality and that over a period of two years it is not likely to deteriorate to such an extent as to make the compass unusable, either as a result of the change of temperature over the range in the following table by any other cause (for example the legibility of graduations shall not be impaired by discolouration or blistering);

　

　

c) under the conditions described in b), that the compass liquid is not likely to show any appreciable discolouration such as to render the compass unusable;

　

d) whether toughened or non-toughened glass is used for the top and bottom glass covers and its thickness; alternatively, when a material other than glass is used, that its strength is equivalent to that of non-toughened glass of 4.5 mm thick-ness;

　

e) that the material of the compass card will not distort;

　

f) that the moment of inertia of the directional system is approximately the same about all horizontal axes passing through the bearing surface of the pivot jewel;

　

g) the vertical distance between the mid-plane of the magnets of the directional system and the inner gimbal axis of the compass supplied;

　

h) the supporting force on the pivot

　

i) in the Class A compasses, that the force exerted on the pivot bearing, in the liquid at 20℃, by the directional system is between 0.04 N and 0.1 N when the card diameter is 165 mm or less, and is that between 0.04 N and 0.14 N when the card diameter is larger than 165 mm. In the Class B compasses, the supporting force shall be such that the directional system always remains in contact with its pivot. (ISO613,4.1.4 e)

　

j) that the inner and outer bearings of the gimbal rings are of the same type;

　

k) the length of bar magnets or diameter of ring magnet forming the directional system.

　

In order to check that the manufacturer's statement above has been fulfilled, sample checks may be carried out.

　

　

　

The compass shall be inspected to see that it is undamaged and mechanically perfect. The liquid shall be colourless and free from turbidity and formation of flocks. There shall be no leaks. The paint, including that on the compass card, shall be free from cracks and blisters.

　

4.2.2.1.2 Non-magnetic properties (type-test only)

Compass bowls and gimbaling shall be tested to verify their non-magnetic properties (see 4.2.2.7.4).

　

The compass shall be warmed slowly from room temperature to 60℃ ±2℃ and kept at least 8 h at this temperature. After this period, the compass shall not show any mechanical damage, leakage or bubbles. The compass liquid and paint shall not show any deterioration, and the directional system shall not be deformed. The compass shall operate satisfactorily.

　

The directional system shall always be in contact with its pivot.

　

The compass shall be slowly cooled to the temperatures in the following table and kept at least 8 h at this temperature. After this period the compass shall not show any mechanical damage or deformation, leakage or bubbles. The liquid in the bowl shall not freeze, discolour or separate into its ingredients. A formation of flocks or ice shall not have occurred within the liquid and the directional system shall not be deformed. There shall be no deterioration in the function of the compass.

　

　

The directional system shall always be in contact with its pivot.

　

4.2.2.1.5 Thickness of top and bottom glass covers (Class A type-test only)

When made of non-toughened glass, the glass covers of compasses (including compasses that have no gimbals outside the bowl) shall have a thickness of at least 4,5 mm.

　

When toughened glass is used, the thickness shall be at least 3 mm.

　

When material other than glass is used, its properties shall be at least as strong as above [see 2.1.2 d)].

　

The thickness of the glass may be measured by means of a micrometer. As this requires the opening of the compass, it shall be done when the other examinations have been carried out.

　

A transmitting system shall not interfere with reading the card or taking bearings with an azimuth reading device.

　

　

4.2.2.2.1 Plane of gimbal axes (type-test only)

The gimbal axes shall lie in one plane, within a tolerance of 1 mm.

　

This test may be carried out from a fixed horizontal reference plane by means of a suitable scale.

　

4.2.2.2.2 Angle of gimbal axes and intersection of vertical planes passing through them (type-test only)

　

The angle formed by the outer and inner gimbal axes shall be the values in the following table. The vertical planes through the gimbal axes shall intersect to within 1 mm of the pivot point. Any end play shall not cause these tolerances to be exceeded.

　

　

The outer gimbal axis shall be in the fore and aft direction.

　

Measurement of the axes angles may be made by means of the test stand graduation, when first one then the other gimbal axis is brought into the vertical plane of view passing through the graduation centre by turning the compass support.

　

Determination of the intersection line may be carried out on a test stand by measuring the displacement of the compass support in a direction perpendicular to either of the gimbal axes.

　

The bowl of the compass shall be mounted so that the verge ring remains horizontal when the binnacle is tilted the angles in the following in any direction and in such a manner that the compass cannot be dislodged under any conditions of sea or weather.

　

　

The measurement may be carried out by a clinometer placed on the top glass cover or verge ring.

　

　

The compass bowl shall be balanced so that its verge ring or top glass cover settles in the horizontal plane to within 2°when the gimbal ring is fixed in a horizontal position. This shall be so whether the azimuth reading device or other attachment or magnifier is in position or not.

Measurement shall be carried out by placing a spirit level of suitable sensitivity on the top glass or its verge ring.

　

When the gimbal ring is kept in the horizontal position and the compass bowl is inclined by ±5°, it shall return to within 2°of the horizontal plane.

The test may be carried out by means of a clinometer or spirit level.

　

4.2.2.2.6 Inner and outer gimbal bearings (type-test only)

The bearings of the inner and outer gimbal axes shall be of the same type.

　

　

4.2.2.3.1 Relative bearing ring radiation (if any)

　

If the compass is provided for taking bearings, a scale graduated in 360° clock-wise, zero, as seen through the azimuth reading device, indicating the direction of the ship's head shall be provided.

　

This graduation shall be checked.

　

If there is a relative bearing ring, the perpendicular to the plane of this ring, through the graduation centre, shall be within 0,5 mm of the pivot point.

　

This may be tested when the compass bowl is dismantled by centring the pivot on the test stand, rotating the compass bowl and observing the eccentricity of the relative bearing ring through the test stand telescope.

　

Alternatively, examination may be carried out on assembled compasses by measuring the graduation diameter and reading the directional error in the test stand. The maximum permissible direction error is given in table 1 as a function of the graduation diameter.

　

　

4.2.2.3.3 Relationship of edge of compass card and pivot bearing (type-test only)

When the verge ring and the seating for the azimuth reading device are both horizontal, the card graduated edge, the lubber mark if a point, the pivot point and the outer gimbal axis shall all lie within 1 mm of the horizontal plane passing through the gimbal axis fixed to the compass bowl. This measurement can only be made when the compass bowl is opened. It can be made using a depth gauge from a fixed reference plane.

　

4.2.2.3.4 Accuracy of centring of azimuth reading device (type-test only)

The distance between the rotating axis of the azimuth reading device (bridge type or ring type) and the vertical rotation axis of the compass card, passing through the pivot point, shall not exceed 0,5 mm.

　

Depending on the construction of the azimuth reading device, the rotation axis may be defined either by an indentation or centre boss on the top glass cover of the compass, or by the centre of the inside or outside of the verge ring, or by the compass bowl outside rim.

　

The examination may be carried out by measuring, on a compass test stand, the displacement which is necessary to bring the compass pivot point, when horizontal, and the rotation axis of the azimuth reading device, one after the other into coincidence with the rotation axis of the test stand.

　

　

4.2.2.4.1 Height of pivot bearing (type-test only)

The pivot point shall not deviate from the horizontal plane through the inner gimbal axis by more than 1 mm. Should the pivot bearing be equipped with a vertical spring suspension, this condition shall be fulfilled when the directional system is completely immersed.

　

When the compass bowl is opened, this examination may be carried out by using a depth gauge, the compass rim being the reference plane.