E-6
HSB Series CRT Display
Ship’s
Active
Error
Compass
Compass
0°
3°
+3°
90°
96°
+6°
180°
183°
+3°
270°
278°
+8°
Average error
5°
4. Align your vessel to one point, then rotate the active compass to reduce the
readout by the average error. Secure the active compass in position with the
locking screw.
Align your vessel to the remaining cardinal points note the readings.
5. Repeat steps 2 to 4 to reduce the average error as much as possible. You
should aim for an error of zero, but in practice may only achieve 2°.
Linearization
The active compass linearization is performed using the Continuous Deviation
Correction. The compass continuously monitors the deviation and, when the
required conditions are met, updates its correction data.
Every time your vessel completes a 360° turn in not less than three minutes,
without any sudden increases in speed, the compass checks the new deviation
data. If this provides more accurate data than already stored, the correction data
is updated.
To ensure the compass has accurate data following alignment, perform the
following procedure.
1. Choose a calm day, and select an area of open water. Ideally, the current
tide effects should be at a minimum.
2. Calculate the size of circle you need to keep your turn rate down to not less
than 45 seconds for each 90° of turn.
You can turn more slowly than this, and you do not need to keep an exact
circle, but if you turn too quickly the deviation data will be ignored.
3. Turn your vessel continously through two full circles (720°) at a slow,
steady speed, keeping the vessel level. You can go either clockwise, or anti-
clockwise.
4. Ideally, continue to turn through a further two circles to ensure you have
obtained accurate data.
The active compass will now correct all heading readings using the deviation
data obtained.
Appendix F:
Connecting an
Active Compass
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