NT888G MK2 AUTOPILOT OPERATING MANUAL
2.23 Autotrim (Automatic Permanent Helm) Assessment … (Continued).
Autotrim Operating Modes.
(i)
Autopilot switched from
STANDBY to ON
-
Autotrim function operational.
(ii)
Autotrim key to OFF
-
Immediately cancels any
(5 second press)
permanent helm rudder
offset angle and disables
the Autotrim function.
Seagoing
Autotrim
(APH)
Assessment.
(i)
Note the mean & steady course manually steered in the STANDBY mode
by reference to the Autopilot
ACTUAL HEADING
display immediately
prior to Autopilot engagement.
(ii)
Engage the Autopilot (switch from STANDBY to ON) and note that the
mean and steady course now steered is as previously observed.
(This confirms that any permanent rudder offset manually determined to
steer the vessel dead ahead has been copied by the Autopilot).
(iii)
If the mean course steered ultimately differs from the Autopilot Heading
Set (Magnetic deviation excluded) this will be automatically corrected over
the timing period associated with the Autotrim (APH) integrator to correct
the mean direction through the water.
(
i.e.
the mean course actually steered will be the same as the course
actually set).
Manual Cancellation of Autotrim (APH) Rudder Offset.
Press the
AUTOTRIM OFF/SET
key for a period of 5 seconds to initiate immediate
cancellation of any existing permanent helm rudder offset. (The Autotrim ‘OFF’
condition will be confirmed by illumination of the keypad corner LED).
Single press
AUTOTRIM
keypad operation will reinstate the Autotrim function.
Manual Reset of Autotrim (APH) Rudder Offset.
A permanent Helm Offset angle, which is correct on an existing heading, may prove
to be totally incorrect immediately after shooting a trawl etc. or on a new heading
particularly when large course changes are ordered.
This might result in the wrong mean direction through the water when initially settling
on the new heading but would ultimately be automatically corrected by the time based
automatic AUTOTRIM correction process.
The time based waiting period can be shortened by manual
SET
intervention as
follows: -
