Chapter 5: Adjusting Autopilot Settings 8-5-13
ST290 Instrument System Owner’s Handbook
Rudder trim
The RUDDER TRIM setting determines the rate at which the autopilot
applies ‘standing helm’ to correct for trim changes caused by varying
wind loads on the sails or superstructure or an imbalance of engines.
The default rudder trim is set when commissioning the autopilot:
• 150G and 400G autopilots will adjust the AutoTrim setting automati-
cally during the AutoLearn (see Section 8, Chapter 4).
• T150 and T400 require manual adjustment of Rudder Trim
(see Section 8, Chapter 4) after the initial seatrial.
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
takes to get back onto the correct course,it alsomakes 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:
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. Use the button to scroll to the RUD-
DER TRIM screen.
2. Use the or button to adjust the
rudder trim level.
3. To move to the next setting press the
button, or to leave the current cali-
bration chapter and save all setting
changes, press the button.
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81183_2 S8.book Page 13 Tuesday, May 6, 2003 9:08 AM
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