COMPASS SWINGING MADE EASY
Introduction
A compass shall be installed as far as possible away from the radio and from a transponder.
Metal objects near the compass will cause indication errors, called deviation errors.
Deviation errors can be compensated by moving small magnets inside the compass by turning either of the 2 screws at the base of the compass with a non-magnetic screw driver, i.e. brass or plastic. You can easily make a small bras screw driver from a brass bolt and grinding it down until it resembles the flat tip of a screw driver.
Procedure
Find a helper
Take the glider to an obstacle free area
Turn all electical instruments on
North – South
With the wings level, rotate the glider until the compass indicates NORTH
Take a bearing along the longitudinal axis of the glider
Rotate the glider exactly 180º such that the longitudinal axis is lined up with the same bearing
Observe the compass deviation from SOUTH and keep this in mind or write it down
Divide the deviation in half
With the wings level turn the NS screw until the compass indicates half the deviation
East – West
With the wings level, rotate the glider until the compass indicates EAST
Take a bearing along the longitudinal axis of the glider
Rotate the glider exactly 180º such that the longitudinal axis is lined up with the same bearing
Observe the compass deviation from WEST and keep this in mind or write it down
Divide the deviation in half
With the wings level turn the EW screw until the compass indicates half the deviation
DONE
In most cases the reasulting deviation is small and it is not necessary to repeat these steps