Magnetic Compass(Deviation and adjustments) requirements

Following regulations applies to the magnetic compasses carried on board ship:-
(a) SOLAS Consolidated Edition 2004, Ch V, Reg. 19.2
(b) IMO Assembly Resolution A.382(X) – Magnetic Compasses Carriage and Performance Standards
(c) STCW Convention, 1978, as amended, and the STCW Code
(d) ISO Standard 2269:1992 - Class A magnetic compasses, azimuth reading devices and binnacles -- Tests and certification

REQUIREMENTS:
(Taken from all above mentioned requirements considering vessels are fitted with class A magnetic compasses)

1.0 Allowed Residual Deviation
1.1 All vessels are required to be fitted with a properly adjusted magnetic compass. The residual deviation, or error, should be 5° or less on all headings.

2.0 When a Compass Should be Adjusted
2.1 Magnetic compasses should be adjusted when:
.1 They are first installed;
.2 They become unreliable;
.3 The observed error consistently exceeds the allowed limit of 5° on one or more headings;
.4 After dry docking, or after repairs or structural alterations have been made to the ship
that could affect its permanent and / or induced magnetism (see paragraph 3.1 below);
.5 Electrical or magnetic equipment close to the compass is installed, removed, or altered;
.6 After one (1) year from when the compass was last adjusted if the required record of compass deviations has not been properly maintained or the record of deviations are excessive; and/or
.7 When deemed necessary by the Master.

3.0 Changes in Magnetism During the Life of a Ship
3.1 The magnetism of a new vessel can be particularly unstable. The same is true following
major structural repairs or modifications. Therefore, the performance of magnetic compasses
should be monitored carefully during the early life of a vessel as well as after repairs or modifications are completed to determine if the compass requires adjustment.
3.2 Masters are advised that it is essential to check the performance of magnetic compasses particularly:
.1 When carrying and after discharging cargoes that have magnetic properties;
.2 After electromagnetic lifting appliances are used for cargo loading or discharging(see paragraph 3.3 below);
.3 Following a casualty in which the vessel has been subject to severe contact or electrical charge, such as a lightning strike; or
.4 After the vessel has been laid up or lying idle since even a short period of idleness can lead to serious deviations, especially for small vessels.
3.3 The retentive magnetic field induced by electromagnetic lifting appliances can alter a vessel’s magnetism, making compasses unreliable. However, a large amount of the
magnetism induced by electromagnetic equipment may subsequently decay. Therefore,immediate readjustment is not advised until the residual deviation of the compass has been determined.

4.0 Monitoring Compass Deviation
4.1 A magnetic compass’ error should be determined at least once a watch while the vessel is at sea and, when possible, after any major alteration of course. The observed error should be recorded in a compass deviation book. 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. An entry should be made in the compass deviation book when a vessel enters and leaves dry dock.

5.0 Compass Adjustments and Repairs
5.1 Adjustment must be made by a duly authorized compass adjuster. If a qualified and certified compass adjuster is unavailable and the Master considers it necessary, then adjustments may be made by the Master provided he has the necessary expertise. Under no circumstances should the same person who surveyed a vessel carry out the compass adjustment or repairs.
5.2 The date of any adjustment and other details should be noted in the compass deviation book.
Such details should include the position of all compass correctors as well as the vessel’sposition and sea conditions when the adjustments were made.
5.3 A compass deviation card should be prepared each time the compass is adjusted. Separate deviation cards should be prepared for the standard compass and the transmitting magnetic compass repeater, if fitted, by comparing headings.
5.4 Repairs should only be made by the compass manufacturer or other competent person or company using proper test facilities. When the work is finished the repairer should supply
the Owner or Master with a certificate specifying the date the work was done and the applicable standards.
(Note:Various flag states may have some different requirements)