ComNav 1500 - P2, Damping of Compass Heading [SEA]; P3, Counter Rudder [CRD]

ComNav 1500 / 1510 Autopilot - 35 -
6.3.3 P2, Damping of compass heading [SEA]
Possible settings are [0] = Minimum to [9] = Maximum.
Set by the APC routine.
This setting is a combination of yaw dead-band (compass
sensitivity) and compass damping. The minimum setting may
only be used under calm sea conditions to avoid unnecessary
rudder correction due to compass acceleration errors.
Smaller boats and high speed boats, which are subject to more
acceleration in lighter seas will have to use higher settings. Larger
and more stable boats can use lower settings since there is less
compass disturbance. Default setting should work on most boats
in light to moderate sea conditions. Following seas, no matter how
rough, require lower settings to catch course error trends
quickly in order to minimize excessive yaw.
6.3.4 P3, Counter Rudder [CRD]
Possible settings are [0] = Minimum to [9] = Maximum.
Set by the APC routine.
This setting senses the rate of change of heading and gives
additional rudder corrections if the boat is rapidly falling off course,
and backs off the rudder as a boat approaches the desired
heading. Its effect is to rapidly catch the tendency to yaw in a
quartering sea, provide initially high rudder control when making a
large course change and to decelerate the swing of the bow, as a
boat approaches the desired course.
Course holding with heavy and difficult to steer boats is greatly
improved when using this feature. Insufficient counter rudder will
allow the boat to overshoot on large course changes. Too much
will cause unnecessary rudder corrections and a tendency to stop
short of coming to a new course, requiring several successive
corrections before easing up to the new heading.
To optimize counter rudder, initially set it to minimum and adjust
the rudder (see, [RUD] 5.3.2). Increment the counter rudder one
step at a time, while testing 40° course changes, until the
boat achieves an overshoot of 1° to 2° or less.
Remember, that any air in the hydraulic system will prevent
precision control.