The linearization process will start automatically
after your vessel has turned approximately 100°
at a speed of between 3 –15 knots. Linearization
requires no user input, however at least a 270°
turn is required before linearization can complete.
The progress bar will ll to indicate progress, the
progress bar will turn Red if the process is paused or
otherwise interrupted. Time it takes to complete the
linearization will vary according to the characteristics
of the vessel, the installation environment of the
EV unit, and the levels of magnetic interference
at the time of conducting the process. Sources of
signicant magnetic interference may increase the
time required to complete the linearization process.
Examples of such sources include:
• Marine pontoons
• Metal-hulled vessels
• Underwater cables
You can speed-up the linearization process by
completing a full 360° turn (at a speed of 3 – 15
knots). You can also restart the linearization process
at any time by selecting the Restart Compass menu
item.
Once the initial linearization is completed the
Deviation page is displayed and the current
maximum compass deviation is shown.
Compass deviation
If the reported deviation is 45° or higher, it is
highly recommended that the EV unit is moved
and re-installed in a location which is subject to
less magnetic interference. After the linearization
process has successfully completed you can check
the current deviation value at anytime from the
diagnostics pages.
Note: If “- -” is displayed as the Deviation value, it
means that linearization has not been successfully
completed yet.
Check the compass heading data
As part of the autopilot system commissioning
process, it is recommended that you check the
compass heading value displayed, against a good
known heading source on various headings.
Note: Once the linearization process has
completed, it is possible that the heading value
may have a slight offset of 2 to 3 degrees. This
is common where installation space is limited,
and the EV unit cannot be properly aligned to the
vessel's longitudinal axis. In this case, it is possible
to manually adjust the Compass Offset value.
Note: Do NOT rely on the reported heading until
compass linearization and alignment is complete.
System monitoring and adaptation
To ensure optimum performance, after the initial
linearization process is complete the EV continues to
monitor and adapt the compass linearization to suit
current conditions.
If the conditions for linearization are less than ideal,
the automatic linearization process temporarily
pauses until conditions improve again. The following
conditions can cause the linearization process to
temporarily pause:
• Boat speed < 3 knots.
• Boat speed > 15 knots.
• Rate-of-turn is too slow.
• Signicant magnetic interference is present
Compass lock
Once you are satised with the compass accuracy,
you can lock the setting to prevent the autopilot
system from completing a further automatic
linearization in the future.
This feature is particularly useful for vessels in
environments that are exposed to strong magnetic
disturbances on a regular basis (such as offshore
wind farms or very busy rivers, for example). In these
situations it may be desirable to use the Compass
lock feature to disable the continuous linearization
process, as the magnetic interference may build a
heading error over time.
Note: The compass lock may be released at any
time, to allow the compass continuous linearization
to restart. This is particularly useful if planning a
long voyage. The earth’s magnetic eld will change
signicantly from one geographical location to
another, and the compass can continuously
compensate for the changes, ensuring you
maintain accurate heading data throughout the
voyage.
Autopilot control
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