Alphatron ALPHASEAPILOT MFC - Page 52

Operating manual ALPHASEAPILOT MFC Issue 1.1 Page 52 of 84
ALPHASEAPILOT MFC
NB. The factory default level is 60
o
and lowering of the trip level should normally be
avoided unless it is determined that the operational performance of the vessel will
benefit accordingly.
Automatic Autotrim Trip Level Calibration.
(i) Switch the Autopilot to STANDBY and enter the Set Up Menu via simultaneous 5
second operation of the CANCEL & CONFIRM keys.
(Vessel now under manual steering control).
(ii) Use the Autopilot Set Course knob to scroll through the Set Up parameters until
AUTOTRIM TRIP is displayed (8
th
parameter) and read the number of degrees
(60
o
, 70
o
etc.) displayed in the centre column.
(iii) Rotate the illum. control (+/-) to set the required trip level.
(iv) Exit the Set Up Menu (5 sec Op CANCEL & CONFIRM keys).
Evaluating/Altering the Autotrim (APH) Time Constant:
In most cases the factory set AUTOTRIM time constant of 300 seconds will be found to be
optimum for a wide range of displacement vessels High Speed Craft will normally use lower time
constants (factory default 50 seconds). However, adjustment to reduce or increase the time
may sometimes be required.
To Evaluate Autotrim Time Constant: -
(i) The Autopilot must be set to ON, the ship stable on course and
the heading noted.
(ii) By altering the trim of the vessel (i.e. shooting a trawl, reducing
engine revs on one engine of twin prop. vessels etc.) The heading will initially
change and will remain incorrect (i.e. difference between course set and course
steered) until the requisite amount of Autotrim is applied.
Correction Period Too Long Reduce time constant *
Correction Period Too Short Increase time constant
* NB. Unnecessary reduction of time constant can degrade overall steering performance. If in
doubt consult Alphatron Marine.
To Alter the Autotrim Time Constant: -
The Autotrim time constant is accessed via the Setup Menu: -
(i) Set the Autopilot to STANDBY and enter the Set Up Menu
(simultaneous 5 secs operation of CANCEL & CONFIRM keys)
(ii) Use the Set Course knob to scroll through the Set Up parameters until
AUTOTRIM SECS is displayed (7
th
parameter) and read the number of seconds
in the centre column.
(iii) Rotate the illum. control (+/-) to to set the required time constant.
(iv) Exit the Set Up Menu (simultaneous 5 sec operation of the CANCEL & CONFIRM
keys).