Operating manual ALPHASEAPILOT MFC Issue 1.1 Page 51 of 84
ALPHASEAPILOT MFC
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 helm 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 the keypad red corner LED). Single press AUTOTRIM keypad operation will re-instate 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: -
(iv) Allow the vessel to settle on the new heading (which may differ from the Course
actually set due to incorrect APH rudder offset).
(v) Press the SET keypad which will immediately accelerate the APH correction process
by automatically estimating and applying the new rudder offset angle required.
NB. Programmable facilities via the Set Up Menu are also included for automatic
Autotrim (APH) reset as follows:-
Automatic Cancellation of Autotrim (APH) Rudder Offset:
A permanent Helm Offset angle which is correct on an existing heading, may prove to be totally
incorrect on a new heading particularly when large course changes are ordered.
This might result in the wrong mean direction through the water when initially setting on the
new heading but would ultimately be automatically corrected by the time based automatic
AUTOTRIM correction process.
However, the Autopilot is equipped to automatically ‘trip’ or cancel any existing TRIM (APH)
rudder offset for any course change ordered in excess of 20° (i.e. 20° to Port or Stbd of the
current course). This automatic trip point is reprogrammable via the Set Up Menu and can be
lowered in one-degree steps from ±180° to ±20°.
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