NMEA Backbone location

[linedoctor]

I have no network connection with most of the peripherals except for radar and sonar on my new-to-me 2020 R29 CB. (Autopilot, upper helm X8612 not showing on the main x8612, no peripherals showing on the command bridge x8612 at all)

The Garmin online troubleshooter suggests starting with disconnecting the power cable to the NMEA backbone. The backbone doesn’t appear to be behind the mirror in the head (behind the helm) Where is it?

Any other suggestions would be helpful. The boat came with this issue as identified at the survey. The previous owners rarely used the boat so had not identified there was ever an issue. Thanks!

 

[pwensinger]

I can't see where the backbone on our boat is either.

 

[S. Todd]

On our 2021 R29S LE the NMEA backbone is accessed from the mid-cabin under the dinette. If you remove the upper panel along the starboard side (there is a light for the mid-cabin in that panel on our boat) the backbone can be found.

 

[Rocky]

I agree with S. Todd about the NMEA backbone on our 2018 R29s.

That being said, a simple turning "off" of the battery switches for a couple minutes will remove any power from the NMEA system completely and perform the same function as unplugging it at the backbone itself.

I hope that helps.

Rocky

 

[Scuba Too]

I have a 2017 R29 CB and the main backbone located as described. That being said it's difficult to get to as it's in a narrow spot under where the throttle is located. More on this below.

The NMEA backbone is typically powered by the Fusion radio and has been for quite some time, though this may have changed since my boat was built at the end of 2016. I learned this when my Fusion 750 radio failed, fortunately under warranty, I replaced it with a slightly newer model 755. However after swapping the radio I was having issues with the autopilot not powering up. When I spoke with tech support I learned that the power option from the radio is really intended for the Fusion remote and not for powering the backbone - and apparently the newer 755 really couldn't provide enough juice. I first looked at adding a power cable to the main NMEA backbone and realized it would be quite difficult to work with because of the tight location. Fortunately with the CB model there's a second backbone up under the CB helm with really easy access and a convenient breaker box to add another fuse. This isn't an option of course of the sedan model but I suspect the backbone is not quite as stressed as there's only the one autopilot controller. Interestingly the Garmin displays have separate power and the autopilots get their power from the backbone (yes I learned quite a bit during this lol). In any event I highly recommend adding the power cable if this hasn't been done on later models (be sure to turn off the power option from the Fusion radio if you go this route).

As Rocky noted turning off the battery switches works well for resetting the system. With the old radio I had to do this fairly regularly (without understanding why of course). With the power cable installed I haven't had to reset in quite some time (except when changing out my batteries but that's a whole other story).

Eric