Furuno autopilot problem

[Westfield 11]

We are just a couple of days from our slip in Jax, but I had to hand steer for 5 hours today due to the autopilot being unable to hold a course. It’s a Furuno NavPilot-711 and it’s never been that great. When we got the boat it would wander one or two degrees to either side of the set course and as time has gone on it has gradually gotten worse. Now it’s hunting 7 to 9 degrees to either side of the set course. I could bear it in the open ocean since it did keep the course overall, just drew a snake shaped line in the sea.

I know this unit can be much better than it is now. I also know that the boat tracks well and has no play or wander in the steering when hand steering. Does anyone have suggestions for where to start with fixing this or with a good Furuno tech?

[Captain Ralph]

Your in bound to Jax? Ortega area?
PM me when your in, We still work with some techs you would welcome onboard. We know some you do not want on board.
If your in Liquordale another day or so, Max shop is great.

[Cricket]

Used to have a Furuno pilot, think it was the same model and it worked really well.
Couple of ideas:
Would start with the compass, maybe something metal got placed near it that that's throwing it off?
How close is the compass course to actual? May need to do a reset on the compass.
Think we had an issue once with the sensor attached to the rudders coming loose, make sure everything is tight and straight.

Good luck.

[Westfield 11]

Thanks for all the tips, we are now anchored just south of St Augustine and will be up on the Ortega River Sunday night. My first step is going to be to inspect the mechanical system: that’s something I feel qualified to do! After that I’ll try to bleed the autopilot system of any air. Unfortunately it will be a while before I’ll be able to test the system functionally since we have other chores that are of higher priority. I hope to find something mechanical wrong and that I can fix that first. If I don’t find anything wrong I’ll PM for the tech’s contact, thanks for the offer.

[eze2bme]

Find your autopilot compass and make sure that no one put an aerosol can anywhere near it - you'll get these exact operating malfunctions. Don't ask how I know!

[Westfield 11]

Just for my information: how close to the compass is “close”, a foot, 6”, 2 feet?

[Beachcomber]

Just for my information: how close to the compass is “close”, a foot, 6”, 2 feet?

From experience I can say that an I-Pad charging 3’ away can cause real problems. I paid $300 for that lesson😎

[racclarkson@gmail.com]

If your ship icon on your plotter is pointed off course from your actual tract and extent varies, it’s probably the fluxgate compass. Could be metallics too close, or could be cabling. I moved my compass 3’ farther fwd from motors because I found a deviation of 13 degrees from just energizing the port motor engine ignition circuit. RPM changes influenced deviations. Funny because starboard alternator was much closer. New shielded cable made no difference. Compass on Aslan is located under cabin stairs with only soft drinks and water stored there. Adjacent AC cable for stair lights has no impact.

Compass Error.jpg
From 2015 off Canaveral. I know it's hard to see. Green line is actual track; red line is boat icon resulting from bad cable connections. The auto pilot tried to follow it's nose. We were zig-zagging worse than a Liberty Ship in a Wolfpack.