Autopilot doesn't stop at end stops

[JimS]

I have a NAVpilot 711c connected to my hydraulic steering on my outboard motors. When trolling at low speed, going into the wind, frequently the wind will push the bow of the boat to one side and the autopilot will try to correct but the pilot will push the steering ram hard up against the end stops and bind it up. It seems that the pilot should stop prior to hitting the stops but it doesn't.
I am set up using Fantum Feedback as I don't have a rudder reference sensor. When I set up the installation I set the end stops in the software slightly before the actual physical ends of travel on the steering rams.

So is this behavior as expected? If so, is there anything I can do to resolve the problem? I am concerned that some part of the steering system may be damaged because the pump puts a large amount of pressure on the system.

Thank you,
Jim

 

[Johnny Electron]

I guess you could say it is by the design and physics. A boat must have enough movement that the pilot can positively control the boat. If the boat is sitting almost idle, with the pilot engaged (not good idea) doesn't allow the course to change when directed by the pilot/rudder resulting in the pilot applying even more rudder. This is why you are hitting hard over. For sabiki mode the engines are running and fighting currents so it is okay that the boat is staying put. If the pilot moves the rudders there will an immediate response to the boat movement which the pilot is looking for. You have two choices. 1) Stop running the pilot without having a little more speed 2) Install a rudder reference unit so the pilot knows the exact rudder location, so it will stop short of the stops. Keep in mind COG/SOG from a GPS needs 3 knots or better to have valid speed information which the pilot is using. I almost expect that if you get an RRU it will stop the hard over to stops BUT it will get a rudder drive error when the boat fails to change movement when commanded by the rudders/pilot due to lack of speed/thrust. It sounds like you are drifting and wish the pilot to steer and without positive thrust that just isn't possible.

 

[JimS]

Thank you for your response and the concise explanation. I now understand better.
And no, I am not drifting, I am trolling but I must keep my speed between 1.5 to 2 knots, sometimes less depending on current. My boat has a considerable amount of windage which causes the problem. I do occasionally get an error message that requires me to restart the pilot, sounds like the rudder drive error you mentioned.

I have heard that another manufacturer has put in a feature that senses the pump hitting the end stops and stopping it at that point. Presumably it senses the increase in amps drawn by the pump which I believe would be fairly simple to add to Furuno pilots in the future (if they haven't already). (I know this from working with 3D Printer stepper motors) Maybe you could relay this to the engineering team for the suggestion box.

Thanks again for your support in this forum.