Raymarine A65, Operation Instructions Manual, Page: 107 / 390

• Marine pontoons.
• Metal-hulled vessels.
• Undersea cables.
Note: You can speed-up the linearization process
by completing a 360 degree 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.
Use the compass deviation indicator
The use of the compass deviation indicator on the
pilot control head may be useful in this process,
particularly if the EV unit has been installed in
a location on the vessel where the levels of
magnetic interference are too high for the EV unit
to compensate appropriately. If this is the case,
the deviation display will indicate a value of 25
degrees or higher. In this scenario, Raymarine
highly recommends that the EV unit is moved and
re-installed in a location which is subject to less
magnetic interference. 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, Raymarine recommends that you check the
compass heading value displayed on your autopilot
control head or multifunction display, against a good
known heading source on various headings. This
will help you to determine when the EV unit has
completed its linearization process.
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 using
the pilot control head or multifunction display, and
fine-tune the heading to an accurate value.
Note: Do NOT rely on the heading accuracy until
you are satisfied that 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 is less than 3 knots.
• Boat speed is greater than 15 knots.
• Rate-of-turn is too slow.
• Significant external magnetic interference is
present.
Compass lock
Once you are satisfied 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 field will change
significantly 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
107