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IS0
FOR STAN DARD I Z AT10 N
I NTERN AT1 ON A L ORGAN IZ AT1 O N
I SO R EC O M M E N DATI O N
R 449
MAGNETIC COMPASSES AND BINNACLES, CLASS A,
FOR USE IN SEA NAVIGATION
1 çt ED IT I ON
October 1965
COPYRIGHT RESERVED
of IS0 Recommendations and IS0 Standards
The copyright
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 449, Magnetic Compasses and Binnacles, Class A, for Use
in Sea Navigation, was drawn up by Technical Committee ISOlTC 8, Shipbuilding Details, the
Secretariat of which is held by the Stichting Nederlands Normalisatie-instituut ("1).
Work on this question by the Technical Committee began in 1956 and led, in 1962, to the
adoption of a Draft IS0 Recommendation.
In May 1963, this Draft IS0 Recommendation (No. 576) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial
nature, by the following Member Bodies :
Australia Greece Spain
Belgium Iran Sweden
Chile Israel Switzerland
Czechoslovakia Italy United Kingdom
Denmark Netherlands U.S.S.R.
France New Zealand
Germany Poland
One Member Body opposed the approval of the Draft:
Japan
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council
which decided, in October 1965, to accept it as an IS0 RECOMMENDATION.
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ISO/R 449 . 1965 (E)
CONTENTS
Page
Introduction . 5
1 . General . 5
1.1 Scope . 5
1.2 Units . 5
1.3 Definitions . 5
1.4 Marking . 7
2 . Magnetic compasses . 7
3.1 Construction and materials . 7
2.2 Mounting . 9
7.3 Directional system . 9
2.4 Graduation . 9
3.5 Accuracy . 10
3 . Binnacles . 10
3.1 Construction and materials . 10
3.2 Provision for correction of deviation . 11
3.3 Accuracy of fore-and-aft marks . 12
. 3.4 Illumination . 12
4 . Azimuth reading devices . 12
4.1 Field of view . 12
4.2 Accuracy . 12
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ISO/R 449 - 1985 (E)
I IS0 Recommendation R 449 October 1965
MAGNETIC COMPASSES AND BINNACLES, CLASS A,
FOR USE IN SEA NAVIGATION
INTRODUCTION
This IS0 Recommendation deals with the general requirements, as regards construction and
performance, for magnetic compasses and binnacles, Class A, for use in sea navigation.
1. GENERAL
1.1 Scope
This IS0 Recommendation refers to liquid magnetic compasses, intended for sea
navigation, having a direct reading system, which may be of the reflecting, projecting or
transmitting types.
In this context, a magnetic compass is an instrument consisting of a directional system
supported on a single pivot inside a bowl which is completely filled with liquid, and which
is supported in gimbals.
Hemispherical compasses, which are not supported in gimbals, are equally covered by this
IS0 Recommendation. The requirements relating to gimbals do not apply to such
compasses.
1.1.1 Exclusion. This IS0 Recommendation does not refer to
(a) dry card compasses,
(b) types of compass designed on principles different from those stated in clause 1.1
above or not complying with the description given in that clause.
1.2 units
In view of the present established practice, the following units have been retained:
the oersted as the unit of magnetic field strength and
the CGS unit as the unit of magnetic moment.
Corresponding units in the International System (S.I.) are
oersted,
for the magnetic3eld strength, A.m-l, which corresponds to 4 x
for the magnetic moment, A.m2, which corresponds to lo3 CGS units.
1.3 Definitions
For the purposes of this IS0 Recommendation, the following definitions apply :
1.3.1 Standard compass. Compass used to navigate a ship.
Compass used by the helmsman when steering a ship.
13.2 Steering compass.
1.3.3 Liquid compass. Compass whose card is immersed in liquid.
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ISO/R 449 - 1965 (E)
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1.3.4 Reflector compass. Compass in which the image of the card can be read as a whole
or in part by means of a reflecting system.
1.3.5 Projector compass. Compass in which the image of the card is projected as a whole
or in part onto a screen by an optical system.
1.3.6 Transmitting compass. Compass which transmits the compass indication to repeater
instruments.
1.3.7 Aperiodic compass. Compass which, after being deflected from its heading, does not
oscillate through a complete period before returning to its heading.
1.3.8 Directional system. Assembly of compass card, pivot bearing and permanent magnets
which, in the absence of magnetic fields due to the ship, settles in constant alignment
with the magnetic meridian due to the action of terrestrial magnetism on the permanent
magnets. The card is graduated and is read against a (lubber mark) which is fixed in
relation to the ship’s head.
1.3.9 Binnacle. Fixed stand for supporting a compass and for housing or supporting the
devices for correcting the compass deviation.
It supports the compass in gimbals so that the effects of the pitching and rolling motions
of the ship are minimized; it contains provision for illuminating the compass card.
1.3.10
Point of compass. Mark on the compass card. There are 32 points to a complete
circle; the arc between two adjacent points being 11.25’.
1.3.11
Deviation. Angle between Magnetic North and Compass North, as indicated by a
magnetic compass.
1.3.12
Coeficient A. Mean of the compass deviations on not less than eight headings equally
spaced round the card.
1.3.13 Coeficient B. Deviation due to the fore-and-aft component of a ship’s permanent
magnetism and to part of the magnetism induced in the vertical soft iron in a ship.
1.3.14 Coeficient C.
Deviation due to the thwartship component of a ship’s permanent
magnetism and to part of the magnetism induced in the vertical soft iron in a ship.
1.3.15 Coeficient D. Deviation due to the horizontal component of the magnetic field
induced in the fore-and-aft and thwartship soft iron parts in a ship.
1.3.16 Coeficient H. Deviation due to the magnetism induced by the magnets of the direc-
tional system in the device used to correct Coefficient D.
1.3.17 Flinders bar. Bar which is placed adjacent to the compass with its axis vertical, and
which is used to counteract the magnetism induced in the vertical soft iron parts in a
ship.
1.3.18 Azimuth reading device. Device, usually mounted on or attached to a compass bowl,
for measuring the azimuth of a distant object, either celestial or terrestrial, that is, for
measuring the angle at the zenith between the observer’s magnetic meridian and the
plane of a vertical circle passing through the object. If the verge ring of the compass
is suitably graduated, it can also give a reading of the bearing of the object relative
to the ship’s head.
1.3.19 Verge ring. Ring for retaining the top glass cover of the compass. It may or may not
be graduated in degrees relative to the ship’s head.
1.3.20 Directional error. Geometrical and constructional error of the directional system,
comprising inaccuracies in graduation, eccentricity of the card on its pivot and inac-
curacies of orientation of the card on the magnet system.
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ISO/R 449 - 1985 (E)
1.3.21 Lubber error. Angle between the vertical plane passing through the lubber mark and
the centre of rotation of the card, and the vertical plane passing through the fore-and-aft
gimbal axis.
1.4 Marking
The following parts should be marked with the information and in the position shown in
Table 1.
TABLE 1. - Marking requirements
Position of manufacturer's name Position of serial number
Name of part
or other means of identification on the part
I
Magnetic (U) Card (U) Card
compass (b) Verge ring (b) Verge ring
(c) Gimbal ring or rings
Binnacle I Any convenient position I Not required
I
Azimuth reading On top of the base of the On top of the base of the
device azimuth reading device azimuth reading device
2. MAGNETIC COMPASSES
2.1 Construction and materials
2.1.1 The magnets used in the directional systems of magnetic compasses should be of a
suitable magnetic material having a high remanence and high coercivity. All other
materials used in magnetic compasses, other than transmitting compasses, should be
of non-magnetic material.
2.1.2 The distance between the lubber mark and the outer edge of the card should be between
1.5 and 3.0 mm. The width of the lubber mark should not be greater than 0.5" of the
graduation of the card. The lubber mark should be of such design as to allow the com-
pass to be read when the bowl is tilted lo" in the case of a gimbal compass or 30" in the
case of a hemispherical compass.
2.1.3 When the verge ring and the seating for the azimuth reading device are both horizontal,
the graduated edge of the card, the lubber mark if a point, the pivot point and the outer
gimbal axis should all lie within 1 mm of the horizontal plane passing through the
gimbal axis fixed to the bowl.
The outer
2.1.4 The gimbal axes should be mutually perpendicular within a tolerance of I".
gimbal axis should be in the fore-and-aft direction of the ship.
2.1.5 The thickness of the top glass cover and of the bottom glass of the compass should be
not less than 4.5 mm, if non-toughened, and not less than 3.0 mm, if toughened. These
values apply also to the thickness of the top glass in hemispherical compasses. If
material other than glass is used, it should be of equivalent strength.
-30 "C to +60 OC,
2.1.6 Within the temperature range
(U) the liquid in the compass bowl should remain clear and free from bubbles, and
neither emulsify nor freeze;
(b) there should be neither inward leak of air nor outward leak of liquid.
NOTE. - This requirement does not apply to the normal functioning of liquid compasses which have
a combined gravity liquid reservoir and free expansion chamber fitted to the top glass cover so as to
allow for changes in the density of the liquid.
(c) paint should not blister, crack or discolour appreciably.
2.1.7 The balance of the compass bowl should not be disturbed by any magnifying glass or
by any azimuth reading device provided for use with the compass.
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ISO/R 449 - 1965 (E)
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Card diameter (in millimetres)
FIGURE. - Magnetic moments of fluid compasses
(Minimum requirements)
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ISO/R 449 - 1965 (E)
2.2 Mounting
2.2.1 The bowl of the compass should be mounted so that the verge ring remains horizontal
when the binnacle is tilted 40" in any direction and so that the compass cannot be
dislodged under any conditions of sea or weather.
The bearings of the inner and outer gimbal axes should be of the same type.
2.2.2 In compasses of the hemispherical type, in which no supporting gimbal is provided,
the freedom
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