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Solas Chapter V - Annex 13 -
Magnetic Compasses
Requriments and Guidance for Magnetic Compasses according to Chapter
V, Regulation 19 of the Safety Of Lives At Sea (SOLAS) Convention
under the International Maritime Organisation (IMO) are stated
below.
1.) Regulation 19, paragraphs 2.1.1, 2.1.2, 2.1.3 and 2.2.1
lay down the requirements for
all ships (excluding fishing vessels and pleasure craft under 150 gt)
to be fitted with
a magnetic compass or other means to determine and display the
vessel’s heading
independent of any power supply. They must also be fitted with a
pelorus, or other
means, to take bearings over an arc of 360° of the horizon and a
means for
correcting heading and bearings to true at all times.
2.) Smaller fishing vessels should make every effort to meet
the requirements of
Regulation 19.
Performance standards
3.) Equipment
must comply with the IMO Performance Standards as follows:
Magnetic compasses - Resolution A.382(X) and
Transmitting magnetic heading devices – Resolution MSC.86(70), annex
2
4.) Regulation 19 requires all ships of 150 GT and over, and
all passenger ships to
carry a spare magnetic compass (or equivalent.)
Responsibility for
Maintenance
5.) The Owner and
the Master are responsible for ensuring that compasses on their
ships are maintained in good working order.
Adjustment of
Compasses
6.) Each magnetic compass required to be carried by the
Regulations shall be
properly adjusted and its table or curve of residual deviations
available at all times.
Magnetic compasses should be adjusted when:
a.) they
are first installed;
b.) they become unreliable;
c.) the ship undergoes structural repairs or alterations
that could affect
its permanent and induced magnetism;
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Solas Chapter V - Annex 13 - Magnetic Compasses
d.) electrical or magnetic equipment close to the compass
is added,
removed or altered; or,
e.) a period of two years has elapsed since the last
adjustment and a
record of compass deviations has not been maintained, or the
recorded
deviations are excessive or when the compass shows physical
defects.
Effects of Changes
in Magnetism During the Life of a Ship
7.) Because the
magnetism of a new ship can be particularly unstable, the
performance of magnetic compasses should be monitored carefully
during the early
life of a ship, and adjustments made if necessary.
8.) Masters are advised that it is essential to check the
performance of magnetic
compasses particularly after:
a.)
carrying cargoes which have magnetic properties;
b.) using electromagnetic lifting appliances to load or
discharge;
c.) a casualty in which the ship has been subject to
severe contact or
electrical charges; or,
d.) the ship has been laid up or has been lying idle -
even a short period
of idleness can lead to serious deviations, especially for small
vessels.
9.) Further to
8(b), the retentive magnetism can alter a ship’s magnetism, making
compasses unreliable. However, a large amount of the magnetism
induced by an
electromagnet may subsequently decay so immediate readjustment is
not advised.
Every effort should be made to determine the compass deviation.
Monitoring Compass
Performance
10.) Compass
performance should be monitored by frequently recording deviations
in the compass deviation book. Compass errors should be determined
after every
large alteration of course, and at least once every watch when there
have been no
major course alterations. Checking the compass deviation regularly
may show the
need for repair, testing or adjustment. In addition, compasses
should be inspected
occasionally by a competent officer or compass adjuster.
Adjustments and
Repairs
11.) In the UK, all adjustments should be made by a compass
adjuster who holds a
Certificate of Competency as Compass Adjuster issued by the
UK Government.
12.) If a qualified compass adjuster is unavailable and the
Master considers it
necessary then adjustments may be made by a person holding a
Certificate of
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Solas Chapter V - Annex 13 - Magnetic Compasses
Competency (Deck Officer) Class 1 (Master Mariner). The compass must
be readjusted
by a qualified compass adjuster at the next available opportunity.
13.) The date of any adjustment and other details should be
noted in the compass
deviation book. The position of correctors should be recorded in the
compass book
and on deviation cards. Because the distances from the coefficients
B and C
correctors to the standard compass card and to the transmitting
element are
different, a transmitting magnetic compass will be overcompensated
resulting in an
error, which can be as much as 2½° and cannot be corrected. Separate
deviation
cards should be prepared for the standard compass and the
transmitting magnetic
compass repeater by comparing headings.
14.) Repairs should only be made by a compass manufacturer or
other competent
person using the proper test facilities. When the work is finished
the repairer should
supply the owner or Master with a certificate, specifying that the
work has been
carried out in accordance with the necessary requirements ISO 2269
for Class A
Compass and ISO 10316 for Class B Compass which are the
International Standards
for the Magnetic Compass.
Portable Equipment that
may interfere with Compasses
15.) Masters and
Officers are advised that portable electrical equipment (e.g. radios
and tape recorders) or items made of steel can affect the
performance of a compass.
Care should be taken to ensure that such items are kept away from
the compass
position. See Regulation 17, para.3
Spare Bowl
16.) When a spare
magnetic compass bowl is required, it should be carefully stowed,
together with its gimbal units, away from the bridge structure so
that they are
unaffected by any casualty disabling the bridge.
Transmitting Magnetic
Compasses (TMC)
17.) If a new or
existing standard magnetic compass is modified to provide a
transmission output then each device must be individually certified
or re-certified
with the transmitting element in place. Re-certification of modified
existing
compasses should be made, with the transmitting element attached to
the compass
bowl. In the UK, the testing authorities are:
QinetiQ
Compass Test Centre,
MOD Portland Bill,
Portland,
Dorset, DT5 2JT. (Formerly the Admiralty Compass Observatory),
and
John Lilley & Gillie Ltd,
Clive Street,
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Solas Chapter V - Annex 13 - Magnetic Compasses
North Shields,
Tyne & Wear,
NE29 6LF.
18.)
Modifications should be made by an experienced compass technician,
who
should ensure that the transmitting element is compatible with the
binnacle. The
performance of the equipment cannot be relied upon until the compass
has been recertified
(as described above) and adjustments have been made by a certified
compass adjuster.
19.) Ancillary equipment included in the modifications (e.g.
electronic units, displays
and power supplies) should be type tested to establish safe
distances from the
compass. In particular, care should be taken to avoid the effect on
the compass of
spurious radio frequency transmissions. Guidance can be found in IEC
60945. See
Regulation 17, paras. 1 & 2
20.) If a transmitting magnetic compass provides heading
information, i.e. it is read
by the helmsman at the main steering position, then the spare bowl
must be fitted
with a transmitting element, and individual testing is required.
Alternatively, if
heading information is provided by the reflected image of a standard
compass or a
separate steering compass, and a transmitting compass is fitted
voluntarily to
provide a repeater facility to navigation equipment, then the spare
bowl does not
require a separate transmitting element.
Emergency Steering
position
21.) Regulation 19, para. 2.1.9, requires a telephone or
other means to
communicate heading information to the emergency steering position,
if provided.
On ships over 500GT a visual reading of the ship’s heading must be
supplied to the
emergency steering position if provided. (See Regulation 19, para.
2.5.2).
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