Alphatron ALPHASEAPILOT MFC - The AUTOTRIM Key (Automatic Permanent Helm); The Alarm TEST;OFF Key

Operating manual ALPHASEAPILOT MFC Issue 1.1 Page 37 of 84
ALPHASEAPILOT MFC
2.7 The AUTOTRIM Key (Automatic Permanent Helm)
AUTOTRIM (Automatic Permanent Helm) is applied by the Autopilot over a period of time when
underway to offset the rudder and eliminate heading errors caused by windage or vessel trim
etc.
The Autotrim function can be permanently switched off if required (confirmed by illumination of
the “AUTOTRIM” key red corner LED) or can be used to instantaneously assess the required
rudder “offset” angle when the Autotrim key “SET” facility is used.
NB. The AUTOTRIM key is also used simultaneously with the TRACK key to enter the
Diagnostic Mode. (Installation and Tech Manual Section TM5).
Most of the Autotrim Set Up parameters are determined during Sea Trials and include the APH
Time Constant and Autotrim Trip Angle, the values of which are set/altered via the Set Up
Menu. (Installation and Tech Manual Section 3.11 to 3.13).
The Set Up Menu also offers special Autotrim operating modes but standard (STD) mode is
normally chosen. In the standard mode, the “AUTOTRIM” key is used as follows:-
(i) Factory default setting is AUTOTRIM active (ON) when the Autopilot is switched
from “STANDBY” to “ON”.
(ii) To switch the Autotrim facility OFF, press the “AUTOTRIM” key for 5 seconds
until the red corner “OFF” LED illuminates. (Autotrim will automatically revert to
the active state when the Autopilot is switched “OFF” and “ON” again).
(iii) Single press the “AUTOTRIM” key to switch Autotrim ON again if the red corner
LED is illuminated (Autotrim off).
(iv) Single press the “AUTOTRIM” key to automatically assess and instantaneously
apply the correct angle of rudder (APH).
2.8 The Alarm TEST/OFF Key
The Autopilot Control Unit is equipped with an audible alarm which, in most cases, accompanies
display indications of alarm and warning conditions.
Under normal operating conditions, the alarm is silent but
becomes active consistent with Watch Alarm timeout period,
OHA level, input data fail etc. and is cancelled/acknowledged
by single press of the “TEST/OFF” keypad.
The audible alarm function can also be permanently turned OFF (muted) by continuous 5
second press of the “TEST/OFF” keypad and is confirmed by the Alarm icon at the bottom left
corner of the Control Unit display.
Once muted, the audible alarm can be restored by double press operation of the same keypad.
An alarm TEST function is available at any time during the STANDBY or ON operating modes
via double press of the “TEST/OFF” key. This is followed by sequential illumination of all nine
keypad corner LED lights accompanied in each case by an audible bleep and a 10
th
bleep at test
end.