B+C Compensation Kit for C20 Compasses

181,50  PRICE VAT incl.

The B+C compensation kit consists of two identical devices, one for B-correction (caused by the ship’s permanent longitudinal field) and one for C-correction (caused by the athwartships permanent magnetism). Each device will correct the compass by 35°-40° degrees. This requires a distance of at least 150mm between the nearest point of the device and the directional compass system. Increasing this distance will reduce the maximum deviation.


Assembly and Operation of the Compensation Kit

  • The distance to any magnetic influence should be at least 50 cm.
  • The compass should be installed outside a closed magnetic iron environment because this will shield the earth’s field.
  • The compass must be installed at a sufficient distance from the influence of any magnetic field: main engine, windscreen wiper motor, fire extinguisher, other compasses, loudspeakers, etc. Any magnetic disturbance can affect the compass. Furthermore, magnetic fields are variable and variable fields cannot in principle be corrected.
  • Unscrew the two screws and remove the U-shaped cover to open the corrector system.
  • Each corrector contains two magnets, which can be inserted into the different holes. The red marked side of the magnets in one direction will have an opposite deflection to the red side in the other direction. The number and distance of the magnets from the directional system determines the magnitude of the deflection. A distant position will cause a smaller deflection.
  • One can fix the device horizontally, vertically or between, it will make no difference.


It is necessary that the magnets are finally oriented exactly fore and aft of the vessel. The C-corrector device for the adjustment of the permanent field to windward has to be fixed or aft of the compass. It is necessary that the magnets are finally oriented exactly to windward of the vessel. Correct adjustment is essential for safe and reliable navigation. It is necessary that the adjustment is carried out by a qualified compass adjuster.

Features of the Compensation Kit

  • Primarily designed for Autonautic C20 compasses
  • Correction 35º – 40º.
  • Black baked marinated aluminium
  • 6 ALNICO magnets included
  • Easy mounting system
  • Suitable for many other compasses