Compass Adjustment
REFLECTA/1
Page C1
Mounting & Operations Manual
Adjustment of Compass
General
Compass adjustment is necessary to neutralize the deflecting magnetic fields caused by the ship´s steel hull or
superstructure.
The first adjustment has to be made on maiden voyage. Later, it should be repeated periodically according to
the requirements of the maritime authority (for ships flying the German flag: two years). Furthermore it should
be carried out additionally on particular circumstances like reconstruction works, lightning stroke, grounding .....
It is necessary to call a qualified compass adjuster for adjustment works.
Before adjustment the vessel must be ready for sea: cargo derricks, hatchway covers, davits.....are to be
positioned as on voyage.
Further details will be found in “Handbook of Compass Adjustment“, Pub. 226 of U.S. Department of Defense,
Defense Mapping Agency.
A-Correction
This is to correct the alignment error of the compass binnacle: Compass ahead and ships ahead have to be
corresponding. For correction loosen the binnacle fixing bolts in the base. Oblong holes in the base allow to turn
the binnacle column by +/-5° around its vertical axis. Attach the azimuth device and take a bearing of a midship
object like masts (provided the compass binnacle itself is located midships) and turn the binnacle so that the
index mark of the azimuth device shows “000“ at the divided verge ring on top of the compass.
B+C-Correction
At delivery 6 B+C magnets (10 mmØ x 200 mm) are to be found in their magazines behind the relevant covers.
See chapter “Compass Binnacle, Outline“.
These are to correct the errors caused by the ship´s permanent longitudinal and cross magnetism. The B-
corrector compensates the longitudinal and the C-corrector the athwardship field. The following picture is to
identfy the magnets. B-magnets are longitudinal and C-magnets are transversal orientated. Correction of +/-40°
deviation is possible to meet the regulations. Choose quantity, orientation and position of magnets as required.
There are 2x10 holes to put in the B-magnets (10 each on port and starboard) and 1x10 holes to put in the C-
magnets. This enables sufficient fine adjustment. Start inserting magnets from the lowest position. The holes
are numbered to note the magnet positions required in the compass diary.
Closed B+C cover, port
uncovered B+C magazines, starboard
B-Magnets, longitudinal orientated
C-Magnets, cross ship orientated
Alterations / Errors reserved
Cassens & Plath GmbH, Kompasshaus, Am Lunedeich 131, 27572 Bremerhaven, Germany, tel. +49 471 4839990, fax +49 471 48399910
www.cassens-plath.de,
