Simrad NAC-2 Commissioning Manual page 21

Rudder gain
This parameter determines the ratio between commanded rudder
and the heading error. The higher rudder gain value the more
rudder is applied. If the value is too small it will take a long time to
compensate for a heading error, and the autopilot will fail to keep a
steady course. If the value is set too high the overshoot will increase
and the steering will be unstable.
A
The value is set too high. Steering becomes unstable and
often the overshoot will increase
B
The value is set too low. It will take a long time to
compensate for a heading error, and the autopilot will fail to
keep a steady course
Counter rudder
Counter rudder is the amount of counteracting (opposite) rudder
applied to stop the turn at the end of a major course change. The
settings depend on vessel's characteristics, inertia, hull shape and
rudder efficiency.
Sea trial | NAC-2/NAC-3 Commissioning Manual
Tuning parameters, AP44
A
B
21