The installation instructions advise that the first task should be to swing the autopilot compass. The is an easy task - after working yourself thru the menus to the right spot in the autopilot's software, you turn the boat 360° taking at least 3 minutes to do so. Apparently all is well with the compass location if the maximum deviation discovered is less than 30° - ours was 8°. At least from the effects of nearby iron (and magnets), the compass location is apparently good. OK!
That picture does not give an adequate description of the behavior. The first time a course correction was needed, the autopilot turned the wheel a little. And then, apparently not satisfied with the boat's progress in the new direction, it turned it again, a LOT. The boat immediately overshot and the autopilot then turned the wheel in the other direction, all the way until the limit switches stopped it. I disengaged it.
I used the rest of the trip to fool with the internal settings, trying to find a way to tone things down a bit. No joy.
Then I said to myself, "Self, I wonder if the rudder transducer is really a required part of the system?" So I plugged it in to the back of the ST5000 and, holding it in my hands, I tried to make it do what I thought it would be doing if it were properly installed and hooked up to the rudder. What did I learn? That the autopilot is exquisitely sensitive to the rudder position. So much so in fact, that I believe that the autopilot is actually commanding a rudder angle directly.
Guess I'm going to have to swallow my impatience and go ahead and install the rudder transducer.
The necessary three-conductor shielded wire is now on order.