Furuno NAVpilot-500 Operator's Manual page 44

Set rudder gain so that the boat does not make frequent yaw. The figure shown below
provides general guidelines for setting rudder gain.
fast
calm
light
low
COUNTER RUDDER
If the boat is heavily loaded, the heading will turn excessively by inertia, passing the new
course. Then, the NAVpilot-500 will steer the rudder to the opposite side and the heading
will turn in that direction excessively again. In an extreme case the heading oscillates
several times until it finally settles in the new course. An adjustment known as "counter
rudder" prevents this kind of oscillation.
Counter rudder is usually not required for small boats. When your boat zigzags a lot before
settling in the new course, increase the setting.
Counter rudder:
small setting
Counter rudder:
proper setting
Boat's Speed
Load Condition
RUDDER GAIN
General guidelines for setting rudder gain
The counter rudder feature functions to smoothly
return ship's heading toward intended course.
Boat's Speed
slow
Load Condition
light
COUNTER RUDDER
low
General guidelines for setting counter rudder gain
Sea State
Large course error
4. MENU OPERATION
slow
rough
heavy
high
Intended
course
fast
heavy
high
4-7