magnetic field at higher latitudes which has the effect of
amplifying rudder response on northerly (southerly)
headings.
Rudder Gain Adjustment
(Sail)
It is not normally necessary to adjust the autopilot gain
setting once the correct level has been established
during initial sea trials.
Depending on the yacht's individual steering
characteristics a change of one level may improve
course keeping accuracy when going from northerly to
southerly (increase) or southerly to northerly (decrease)
headings.
The effect may be judged by carrying out a sea trial in
smooth water conditions and observing the results.
Note:
The effect is reversed for the Southern
hemisphere.
Rudder Gain Adjustment
(Powercraft) The tendency
towards northerly (southerly) heading instability is more
obvious in high speed craft and can be corrected by a
reduction in the rudder gain sefting. At speeds in
excess of 30 knots a reduction of two levels can be
required on headings between 315 deg. and 045 deg
(Northern hemisphere) or 135 deg. and
230
deg.
(Southern hemisphere).
Two options are available to control this:-
•
Manual
(Low speed and displacement craft). The
rudder gain control may change by one level when
going from northerly to southerly (increase) or
southerly to northerly (decrease) headings. The
effect may be judged by carrying out a sea trial in
smooth water conditions and observing the results.
Note:
The effect is reversed for the Southern
hemisphere.
•
Autoadapt
(High speed planing craft)
The ST7000 can be set automatically to reduce the
effects of northerly heading instability. This feature is
selected in calibration mode by entering the latitude (see
Installation Handbook, Calibration, section on 'Auto
Adapt'). When selected the ST7000 automatically
adjusts the Rudder Gain depending on the compass
heading, removing the need for manual adjustment.
Rudder Gain/Speed Adjustment
(Powercraft) High
speed planing craft exhibit very different steering
characteristics when on and off the plane. As a result it
is generally necessary to adjust the Rudder Gain setting
when going from displacement speed to planing speed
or vice versa.
Two options are available to achieve this:
•
Automatic
When the ST7000 is used with an Autohelm S150
Speed Instrument or Tridata, Rudder Gain is
adjusted automatically with boat speed. There
should be no geed for any manual adjustment.
•
Manual
(No ST50 Speed/-Fridata)
The Rudder Gain setting may be increased by one or
two levels when dropping from planing speed to cruise
speed and decreased by the same amount when
returning to planing speeds.
Note:
It is important to make the gain adjustment
after
dropping to displacement speed and
before
returning to
planing speed.
Note:
The adjustment of Gain with boat speed is
normally only required for high speed planing
powercraft.
Unsatisfactory Steering Performance
If the ST7000 has been installed and set up in
accordance with the instructions in the Installation
Manual it will provide excellent steering performance
over a wide range of conditions.
It performance drops but the autopilot is still working
correctly, the following simple checks should find the
fault:-
•
Has a magnetic influence been introduced near the
fluxgate compass? i.e. anchor, chain, radio
equipment, loudspeaker, tools, generator etc.
Check that the autopilot compass heading still
corresponds with the steering compass.
•
Are all fuses intact, circuit breakers engaged?
•
Are all screw connections tight and free of
corrosion?
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