Alphatron ALPHASEAPILOT MFC - Optimising the Yaw Control Setting

Operating manual ALPHASEAPILOT MFC Issue 1.1 Page 54 of 84
ALPHASEAPILOT MFC
NB. If overshoot persists despite a high Counter Control setting it is likely that the
AUTOTRIM Timing Period is too short and can be evaluated as follows: -
(vi) Set the Autotrim key OFF.
(vii) Use the Autopilot Set Course Control to order a 30° course change.
(viii) If there is now no overshoot or the vessel is prematurely arrested turning to the
new heading the AUTOTRIM Time Constant must be increased. (See Section
2.23).
2.25 Optimising the Yaw Control Setting
The YAW control setting defines the Autopilot sensitivity to short term yaw or course error and
determines how much short term error will be tolerated before corrective rudder is ordered.
A minimum YAW setting (N°1) prescribes maximum Autopilot sensitivity (±0.7°) increasing
linearly to a maximum setting (N°9) for minimum sensitivity (±10°) (i.e. minimum yaw =
maximum sensitivity and vice versa).
NB. The minimum yaw setting limit of ±0.7° referred to above does not restrict the Autopilot
in it’s ability to maintain heading control more accurately than ±0.7°. In practice, the
cumulative effects of Counter Rudder and Autotrim (APH) combine to produce an overall
resolution of ±0.2°.
This combined effect is particularly important in heavy sea conditions when the YAW control
setting can be increased to prevent unnecessarily frequent rudder movements in response to
sea state induced yaw. In such conditions and despite the wider deadband (increased tolerance
to natural yaw) the Autopilot will continue to monitor and control the mean course accuracy as
a function of the Autotrim (APH Integrator) with a higher long term resolution than the Yaw
control setting would otherwise permit.
As a general rule, the Yaw control should be set at the lowest number that provides
the required course keeping sensitivity and ‘straight wake’ performance but avoids
unnecessary rudder movements in response to natural Yaw.
The Yaw control is adjusted via the CONTROLS Menu:-
(i) Use the CONTROLS key three times to enter the Controls Menu and select YAW
(followed by flashing digit 1 to 9).
(ii) Rotate the illum. control (+/-) to increase or decrease the setting as required.
(iii) Timeout and retention of new setting will occur automatically when the display
will revert to the standard operating mode.