Instruction manual

4.5 Autotrim
Under differing conditions a helm bias (sometimes known as
standing helm or rudder trim) is applied, in order to steer a
straight course. An example is when sailing close hauled,
where the vessel will normally pull into the wind, and the
helmsman applies a standing helm to leeward, in order to
maintain course. The amount of this standing helm varies
according to factors such as strength of wind, boat speed, sail
trim and amount of sail set. If no account of these were taken,
the vessel would tend to veer off course, or pull around head-
to-wind when sailing close hauled.
The Wheelpilot continuously monitors the average course
error and applies a bias to the helm to compensate until the
optimum condition is reached (Fig 4.7). This bias, or standing
helm, is applied gradually, so as not to upset the normal per-
formance of the Wheelpilot. Thus, it may take up to a minute
or so to fully compensate after changing tack. Once optimum
trim is reached, the pilot will still monitor for changes in the
prevailing conditions and update the trim accordingly.
NOTE Autotrim is applied automatically and cannot be manually
adjusted.
WP32 Wheelpilot
18
E04596
Wind &
Tide
Ideal course
C
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A
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Fig 4.7 - Effects of Autotrim