Navico NAC-2, Commissioning Manual

Page: 24 / 44

Tuning the autopilot
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Note:
Tuning of the autopilot must be done separately for low
and high speed profiles.
Both Autotune and manual tuning should be performed in
calm or moderate sea conditions.
Providing you have entered correct vessel type, length and cruising
speed, you may not have to perform further manual or automatic
tuning.
Proceed as follows to verify satisfactorily steering:
1.
Stabilize the vessel on a heading, and then select
AUTO
mode
2.
Observe course keeping and rudder commands
- The autopilot should keep the vessel on the set heading
within an average of +/-1 degree, providing calm sea and
wind
3.
Make some small and bigger heading changes to port and
starboard and observe how the vessel settles on the new
heading
- The vessel should have a minimum of overshoot. See
"Rudder
gain"
on page 26 and
"Counter rudder"
on page 26.
If the autopilot is not keeping the heading satisfactorily or not
making the turns satisfactorily, you may now either try the Autotune
function or go directly to manual tuning.
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Note:
If the vessel is more than approximately 30 m/100 ft or
has a very high cruising speed it may be unpractical to perform
Autotune. It is then suggested to proceed with manual tuning.
Autotuning
When performing an autotune, the vessel will automatically be
taken through a number of S-turns. Based on the vessel behavior,
the autopilot will automatically set the most important steering
parameters (Rudder gain and Counter rudder).
• Stabilize the vessel on a heading and set the speed between 5-10
kn, then select
Autotune
.
- The autopilot will now switch to AUTO mode and take control
of the vessel.
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Note:
Autotuning can be stopped at any time by pressing the
STBY
key on the autopilot controller.
24
Sea trial | NAC-2/NAC-3 Commissioning Manual