Autopilot Is Not Receiving Navigation Data message

[GZigmont]

Twice on our cruise this past week, I received the above message on the Garmin Chartplotter on our 2019 R29 CB and the autopilot reverted to a heading hold. I stopped the boat, turned everything including the engine and ignition off and then rebooted, starting with the Chartplotter, then autopilot, then engine. This did not rectify the problem. The boat would navigate to the beginning of the route and would only engage a heading hold. I tried to start the route again, but the boat would only run circles. I continued 35 nm to our destination with no problem as it's a route I've taken many times. The magenta line of the route would still display on the chartplotter, and the autopilot would work on a heading hold. Just wouldn't follow the route.

I did a software update using Active Captain at our first port of call and had no further problems on the next four legs of our trip. The problem reoccurred on the last leg, which was the same leg as the first, except in reverse. Got the same message on the chart plotter and the the boat again ran circles when I went back to the starting point of the route. After about a third of our way home, I did the full reboot. I was able to have the autopilot follow a route that was about two thirds of the way from our home port and it worked fine.

Completely puzzled: 1. Reboot didn't work the first time, but worked the last. 2. Software update seemed to work, but the problem reoccurred. 3. GPS and autopilot appeared to be working fine, but independent of each other when the problem occurred.

Anyone have any experience with this? Ideas?

 

[Diatom]

I've been getting the same message over the past week (only).
Reboot always recovers normal functionality.
Location Gulf Islands BC.
No apparent loss of main GPS functionality.

 

[knotflying]

I would check all the connections at the control box which is usually located near the pump. Unscrew them, check for any corrosion and reinstall with a light coating of dialectic grease.

 

[CruisingElvinRay]

Here’s a warning from the owners manual. What is your heading source set to?

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[Ralf H]

hi Gzigmont,

CruisingElvinRay has it right. The issue may well be with your heading source setting. Do the following:

1) From the autopilot screen, select Menu > Autopilot Setup > Preferred Sources
2) Select a source

You should have a choice for your Garmin GPS chart plotter. That would be the required source. Select that and try running the system again to see if you get the same issue. Hope this helps.

Cheers,

Ralf

 

[CruisingElvinRay]

I would disagree that the plotter needs to be the source. It should be the CCU compass, per the manual. The plotter may work, but why not use the CCU compass built in to the autopilot?


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[Wee Venture]

Our autopilot is set to the internal compass for the heading source as mentioned by CruisingElvinRay. It uses this for “Heading Hold.” When following a route it uses “gps steering.” This has worked well and I believe is the preferred method.

John

 

[it4llc]

Reading this I'm wondering if those differences account for the odd steering I get sometimes on autopilot. The heading hold usually stays fairly straight, but when using the follow route option with the GPS steering, it sometimes wanders from port to starboard, sometimes swinging as much as 30-40 degrees according to my compass.

 

[palle]

I had the exact same problem as the original poster. My Heading source is configured as CCU. The plotter gets the heading from the CCU via the NMEA 2000 backbone. In my case the cable from the CCU to the backbone was loose. I tightened it and all has worked fine since. So suggestion is to check connection to the backbone for the plotter and CCU both. Hope this helps your problem also.

 

[CruisingElvinRay]

Reading this I'm wondering if those differences account for the odd steering I get sometimes on autopilot. The heading hold usually stays fairly straight, but when using the follow route option with the GPS steering, it sometimes wanders from port to starboard, sometimes swinging as much as 30-40 degrees according to my compass.

I’ve had some of that (not to that extreme) fighting a crosswind in a narrow canal (the alligator/pungo canal, if memory serves). AP wants the boat to stay on the route, so it fights to stay there. Blown off the route, it makes a noticeable correction. Then straightens out, then blown off the route, then corrects again…


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[GZigmont]

Thank you, all. I will check into all of your suggestions. I do think that the problem is probably not the source. The system worked fine all last year after I set it up, including using those particular routes. I've made no changes and all the other routes work fine. I will check the NMEA trunk and autopilot connections.