Chapter 1: Procedures
11
Swinging the compass
Note:
This section does not apply if you have connected an NMEA compass to your SPX sys-
tem. Refer to the handbook supplied with the NMEA compass for information about calibration.
The magnetic deviation correction procedure (commonly called “swinging the
compass”) involves turning your boat in slow circles so the autopilot can automatically
determine the deviation and apply any correction required. This procedure reduces
deviation errors to a few degrees.
As magnetic deviation can cause significant compass errors on your boat, you MUST
complete the compass swing before any other seatrial procedure.
To swing the compass:
1. With the SPX system in Standby mode, enter Seatrial calibration as follows:
i.
Hold down
standby
for two seconds to enter Calibration mode.
ii. When you see the DISPLAY CAL screen, press
disp
until you see the
SEATRIAL CAL screen.
iii. Press
auto
to enter Seatrial calibration.
Note:
If you cannot access Seatrial calibration, disable the calibration lock. (see
page 28
).
2. Use
disp
as necessary, to move through the Seatrial Calibration items until you
see SWING COMPASS.
3. When you are ready to start, press
+1
, or turn the
rotary control
clockwise, to
select SWING COMPASS ON.
4. Press
auto
to start the compass swing. The controller will display TURN BOAT
indicating the start of the calibration process.
5. Ensuring you keep the boat’s speed below 5 knots, start slowly turning the boat in
circles at a constant speed, maintaining a turn rate of approximately 3° per
second, i.e. taking approximately 2 minutes to complete one turn. Complete at
least two circles, in this manner.
If you turn the boat too quickly, the display will show a TOO FAST message. If this
occurs, apply less helm to reduce the rate of turn.
Note:
If necessary, you can quit the correction process by pressing
standby
or
disp
. If you then
want to repeat the deviation correction, return to the
SWING COMPASS
screen.
2 sec
x2
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81307_1.book Page 11 Wednesday, December 19, 2007 11:17 AM
