8-4-20 Section 8: Autopilots
ST290 Instrument System Owner’s Handbook
Further adjustments
You may also need to adjust the RUDDER TRIM setting. Rudder trim
determines how quickly the autopilot applies ‘standing helm’ to correct
for trim changes, caused for example, by changes in the wind load on the
sails or superstructure, or an imbalance of engines.
Before attempting to adjust the rudder trim setting, use your autopilot for
a period of time, to gain experience. On sail boats you can only evaluate
the effect of rudder trim while under sail.
Although an increase in rudder trim level reduces the time the autopilot
takestoget back onto the correct course, it also makes the boat less stable.
Therefore:
• If the autopilot gives unstable course keeping and the boat snakes
around the desired course, decrease the rudder trim level.
• If the autopilot hangs off course for excessive periods of time,
increase the rudder trim level.
If necessary, use the RUDDER TRIM screen to change the setting. The
possible settings range from OFF (no trim correction) to 4 (fastest trim
correction). Always adjust in single steps and use the lowest acceptable
value.
To adjust the Rudder Trim:
4. Press
AUTO to check the autopilot performance in Auto mode.
Note: 150G and 400G autopilots have a ‘FastTrim’ feature within Rud-
der Trim. Select RUDDER TRIM OFF to disable both FastTrim and Rudder
Trim.
1. Access Pilot Advanced Calibration
andusethe buttontoscrolltothe
RUDDER TRIM screen.
2. Use the or button to adjust the
rudder trim level.
3. To save the setting change, press the
button.
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81183_2 S8.book Page 20 Tuesday, May 6, 2003 9:08 AM
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