Navitron NT888G MK2, Operating Manual

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NT888G MK2 AUTOPILOT OPERATING MANUAL
2.4 The CONTROLS Menu / Rudder Control (Continued).
c) Use the rotary (+/-) illum. control to set value “ 1-9 ” as required.
The Rudder Control is principally employed to prevent Autopilot “Understeer” and
“Oversteer” and the operator control band may be optimised by use of Loop Gain
adjustment (Section 2.22) during later Sea Trials.
2.4 (iii) YAW Control.
This control defines the sensitivity of the Autopilot to course error and is
manually adjusted in the Non Adaptive Mode. It also requires manual
adjustment in the Adaptive Mode unless HSC (High Speed Craft) operation is
selected when the automatic “Weather” function becomes active.
Rated 1 to 9, a “ YAW ” value of 1 specifies minimum Yaw (max. sensitivity) when
the Autopilot will respond to course error of ±0.5°. At maximum Yaw (9) a
deadband of approx ±10° is prescribed.
(Whilst the term “Deadband” is used it should be noted that provided the
AUTOTRIM feature is operational, the Autopilot will ensure that the average
course is maintained whilst disregarding short term course errors arising from
pitch and roll etc. thus avoiding unnecessary Rudder movement).
As a general rule the Yaw control should be set to provide good sensitivity, which
would normally be reduced in heavy weather. (See Section 2.25).
To adjust the YAW value:-
a) Use the “ CONTROLS ” key to enter the Controls Menu.
b) Use the “ CONTROLS ” key again to select “ YAW ” box followed by
flashing value “ 1-9 ”.
c) Use the rotary (+/-) illum. control to set value “ 1-9 ” as required.
2.4 (iv) COUNTER Control.
Like the RUDDER Control, in the Adaptive Mode, the “value” of the COUNTER
(Rudder) parameter will be found automatically (after initial Sea Trial calibration)
by reference to input speed and draft data etc. Even so, the
COUNTER value can
be manually changed – to immediately optimise the steering performance – if
required via the
CONTROLS Menu.
The “ COUNTER ” value (1 to 9) prescribes how much opposite rudder is applied to
prevent overshoot in a turn, or, how much additional rudder is applied to arrest a
sudden or fast and unspecified departure from the Set Heading. (Section 2.24
refers).
To adjust the COUNTER value:-
a) Use the “ CONTROLS ” key to enter the Controls Menu.
b) Use the “ CONTROLS ” key again to select “ COUNTER ” box followed by
flashing value “ 1-9 ”.