Adjusting a compass

"A" Adjustment :

A more or less equal deviation + or - on all headings, can be neutralized by rotating the sensor in the bracket and a fine adjustment can be done with the "A" potentiometer. On delivery this potentiometer is set in the neutral position. Do not rotate the sensor after adjusting the other deviation components. This will 'damage' the made adjustments. Therefore adjust A-deviation before starting the adjustments of the other deviation components (B, C, D and E). If the A-deviation is more than 5 deg., rotate the sensor in the bracket first, but not further than the scale on the sensor. Then use the "A" potentiometer for fine adjustment.
Formula to calculate A correction is :

A=(dN+dNE+dE+dSE+dS+dSW+dW+dNW)/8

"B" adjustment :

With "B" the deviations on the E/W segment can be eliminated. With the switch the compensation direction can be selected: +, 0 or -. With the potentiometer the range is set. With the switch in "0" position no correction is made. After compensation has been carried out, leave the potentiometer and the switch in set position.
Formula to calculate B correction is :

B=(dE-dW)/2

"C" adjustment:

With "C" the deviations on the N/S segment can be eliminated. With the switch the compensation direction can be selected : + or -. With the potentiometer the range is set. With the switch in "0" position no correction is made. After this has been carried out, leave the potentiometer and the switch in position.
Formula to calculate C correction is :

C=(dN-dS)/2

"D" adjustment :

With "D" the deviations on the NE/SE and SW/NW segments can be eliminated. With the potentiometer the range is set. On delivery this potentiometer is set in the neutral position. After compensation has been carried out, leave the potentiometer in position.
Formula to calculate D correction is :

D=((dNE-dSE)+(dSW-dNW))/4

"E" adjustment :

With "E" the deviations on the N/E and S/W segments can be eliminated. With the potentiometer the range is set. On delivery this potentiometer is set in the neutral position. After compensation has been carried out, leave the potentiometer in position.
Formula to calculate E correction is :

E=((dN-dE)+(dS-dW))/4

"V" adjustment :
Best executed by a compass adjuster who has the means to measure the disturbing vertical magnetic field of the ship. 'Nervous' heading indication is an indication this should be done. By trail and error you can find a 'calmer' heading indication which means a 'good adjustment' of the vertical magnetic field. A 'more nervous' heading indication means a 'bad adjustment' of the vertical magnetic field.

N.B.
This adjustment can only be executed when the delivered sensor of the system is the ITH Type MC5 and the system has the V-adjuster potentiometer(s).

N.B.
The companies mentioned on this page employ official compass adjusters.

N.B.
The adjusment ranges of products with "WHEELMARK" comply to ISO11606.