I recently witnessed a possible accident with the autopilot in my boat.
While going under autopilot a guest accidentally put her arm into the
wheel among the spokes and was caught at a wheel turn between a spoke
and the tiller post. The servo is quite powerful so that she was able
to withdraw the arm only after switching off the unit which took few
seconds - still too much. Fortunately only few bruises and some panic
but I fear that it could have gone worse. Any experience? Wouldn't it
be safer to put a panic shut-off switch somewhere? I mean the little red
mushroom to push in case of problems. I have never seen such things
mentioned in autopilot manuals.

Daniel