Checking Autopilot Operation; Checking The Rudder Gain - Raymarine ST4000+ Owner's Handbook Manual

81131_7.book Page 85 Wednesday, March 17, 2004 3:59 PM
Chapter 6: Setting-up the ST4000+

Checking autopilot operation

Checking the rudder gain

After calibrating the compass, familiarize yourself with autopilot
operation:
1. Steer onto a compass heading and hold the course steady.
2. Wheel Pilot: Engage the wheel drive clutch.
Tiller Pilot: Place the push rod end over the tiller pin.
3. Press auto to lock onto the current heading. The autopilot should
achieve a constant heading in calm sea conditions.
4. Use the -1, +1, -10 and +10 keys to check that the autopilot alters
the course to port and starboard in multiples of 1° and 10°.
5. Press standby and disengage the autopilot to return to hand
steering:
• Wheel Pilot: disengage the wheel drive clutch by rotating the
clutch lever anti-clockwise
• Tiller Pilot: remove the drive unit from the tiller pin (if
required, retract the push rod using -1, +1, -10 and +10 keys)
The rudder gain level set at the factory will provide stable control for
initial sea trials. However, boats can vary widely in their response to
helm, and by adjusting the rudder gain you can improve the
autopilot's steering characteristics.
Complete the following test to determine whether the rudder gain is
set too high or too low:
1. Sail your boat at cruising speed in clear water:
• you will find it easiest to recognize the steering response in
calm sea conditions where wave action does not mask basic
steering performance
2. Switch the autopilot to Auto, then make a 40°course change by
pressing the -10 or +10 key four times:
• if the rudder gain is adjusted correctly, the 40° course change
should result in a crisp turn followed by an overshoot of no
more than 5°
• if the rudder gain setting is too high, the 40° course change
will result in a distinct overshoot of more than 5° (A)
Correct this oversteer by reducing the rudder gain setting.
• if the rudder gain is too low, the boat's performance will be
sluggish – it will take a long time to make the 40° turn and
85