Raymarine Autohelm 100, Install Manual

Page: 88 / 109

Chapter 4: Calibration 87
Rudder Deadband (Rudder Damping)
The factory setting for Rudder Deadband provides stable rudder position-
ing on most steering systems. However, some steering systems that use
a rotary or hydraulic drive unit a long way from the rudder may experience
slight instability. This instability can be minimised by increasing the setting.
The settings available are as follows:
Range 1 to 9
Default setting 1
81004-27
Magnetic Variation
Variation tells other equipment the level of magnetic variation present at
the boats current position. Local variation should be entered using the
appropriate keys.
The settings available are as follows:
Range 30 degrees West to 30 degrees East
Default setting Off
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Auto Adapt
It may be noticed that the autopilot tends to be a little less stable on
northerly headings in higher latitudes of the northern hemisphere and
southerly headings in the southern hemisphere. This is caused by the
increasing angle of dip of the earth’s magnetic field at higher latitudes. This
has the effect of amplifying the rudder gain on northerly (southerly)
headings, affecting all magnetic compasses and getting worse the further
away from the equator you are.
The autopilot is able to compensate for this and provide precise course
keeping on all headings by automatically adjusting the gain of the autopilot
depending on the heading.
It is recommended that for high speed craft the Auto Adapt facility is
selected. This automatically reduces the effects of Northerly/Southerly
heading instability.
This feature is selected in calibration by entering the vessel’s operating
latitude. When selected it automatically adjusts the Rudder Gain depending
on heading removing the need for manual adjustment.