Originally Posted by
alex90
If you were to overcontrol the rudder on a yacht in light-moderate swell, you will do more harm than good
I've had an autopilot do that - there seemed to be some time constant in the control loop that give us positive feedback with that day's particular waves. It really did seem to be doing its best to roll the mast out of the boat.
After discussing this with the captain for a few seconds (I had the helm when this started happening) we knocked off the autopilot and steered by hand for the next few hours.