The swing must be performed by sailing CLOCKWISE in a circle at a constant
rate. (If the turn is anticlockwise, the turn bars all point left, to indicate that cor-
rect results cannot be achieved.) The display shows the turn rate in degrees per
second. Any fixed value between 0.5
˚
and 2
˚
/second is acceptable, and the most
important thing to achieve is a CONSTANT rate within this range. It can usually
be achieved with a fixed throttle setting and a fixed rudder setting. If the rate of
turn is too fast, the steering bars flow to the left (to indicate
“
slow down
”
), where-
as they flow to the right (
“
speed up
”
) if the rate of turn is too slow. When a rate
between 0.5
˚
and 2
˚
/second is settled on, the turn bars return to their rest posi-
tion, without moving, to indicate that the turn rate is satisfactory. At 0.5
˚
/second,
a full 360
˚
degrees will, of course, take 12 minutes to execute, and at 2
˚
/second a
full 360
˚
will take only 3 minutes. The accuracy of the compensation is better at
lower turn rates.
When a steady turn rate has been established, press ENTER to enter the error
logging phase. The display changes to show a rotating symbol and a progress
count, starting at 9. All the previous compensation values are immediately
cleared. If it desired simply to clear the settings, simply press any key during the
swing to return to Engineering.
As the constant-rate turn proceeds, the progress indication counts down. It is
vital to maintain the previously-chosen constant turn rate during this phase.
When the progress indication falls to zero (after turning just over 360
˚
), the swing
is complete, and the compass deviation values are automatically calculated and
stored. The display returns to normal Compass mode to show that swinging is
finished and that it is no longer necessary to continue the constant-rate turn.
HEADING ADJUSTMENT
It may be necessary to make a minor adjustment to the sensor alignment to
ensure that the Compass correctly measures the vessel
’
s heading. If an adjust-
ment is found to be needed, accurately point the vessel to a known heading.
Either MAG. or TRUE is displayed to remind the user which physical alignment of
the vessel is to be used.
If the display does not show the known heading, the sensor unit must be rotated
slightly to bring the display into alignment. Slacken the sensor unit
’
s mounting
screws sufficiently to allow the unit to be turned, and rotate it until the display
shows the known heading. Then re-tighten the sensor unit
’
s mounting screws to
lock the compass calibration at that position.
6: WIND
6:1 PRE-TEST OF INSTRUMENT
Before mounting check that the instrument is complete and undamaged. Plug
the sensor into the display unit and apply 12 volts. Gently spin the wind cups
and the wind vane and check the operation of the display.
