NMEA networking between chartplotter and radio

[C-Wolfe]

Are both terminator necessary or can one end be use to connect a device or power cable instead?

[jkidd]

There are many devices out there that get there power from the Nmea 2000 network so that you don't have to run more power wires to every device. Makes for a cleaner network. Lowrance is on there third generation of connectors the first two required adapters or making your on cables to make it work. I think Ray Marine is the only hold out now. If your going to use all Ray Marine products then it doesn't really matter.

[jkidd]

[zuunami]

We were thinking of having the primary backbone underneath the helm box (this is a 16' cruiser), and initially just connecting the chartplotter and a VHF. Then we could use an extension cable to add Ts to the stern of the boat for other sensors. My only remaining question is whether the backbone power supply can just be from the starting battery (through the switch), as that's the only battery we use - we don't have the need for a lot of power on the boat, so don't have the other battery hooked up, just onboard as a backup. Am I misreading the following, or are we fine just hooking up to the starting battery?

From a furuno backbone installation guide: The NMEA 2000 network is designed to be electrically isolated from other circuits to prevent radio interference, so a dedicated network power source is required. The range should be 9 -16V. The network power source should be either single-point connection of a battery or one or more isolated power supplies distributed along the network, but it should not be a combination of battery and power supply connections, and each power line should have
its own fuse.

[ssobol]

[Hunkydory]

For my choice of a raymarine axiom chart plotter & EU150 auto pilot, I used raymarine nmea 2000 Seatalk for the backbone, then for the standard horizon gx2400 vhf radio & the twin Honda motors used adapters to their nmea 2000. No problems with the interfaces other than going into the radio & chart plotter settings to get right choice of gps input to make AIS show up. This I did on the water during the first day of this years Alaska cruise, when the AIS signals wouldn’t show on the axiom chart plotter. It was somewhat of a struggle figuring which GPS signal from either the chart plotter or radio needed to be used & settings to be made. While working on this , I was also trying to get the sonar working while going down the Lynn Canal. Somewhat due to this, when I got the AIS to show on the chart, I failed to write down, what I did, so if needed done again, I will have to go through the same process again or possibly now go through the settings to see how it’s presently set. The AIS signals on the radio screen to me are pretty much worthless, but show up great on the chart plotter.

Robert, I got power for the backbone from one of the connectors going out of a fuse block with multiple fused connections used for other electric items needing a power source. It is directly wired to the house/start batteries & I have had no interference problems.

Jay

[zuunami]

Great, Jay, thanks!

My other question now that I am looking at actual systems/parts is whether there is any benefit of starting with a T block under the helm box instead of multiple Ts? It seems they are usually a block of 4, and I assume one could be used for power - if you only use three of the four T "ports" initially, would you need to somehow cap the unused T off? - Karen

[jkidd]

Yes you can start with one of the 4 port connectors and they do make caps for the unused ports.

[Hunkydory]

And I used multiple sets of 3 port sea talk, each connected by short back bone line instead of many many single ports connected directly together.

Also Jody was my best source of help during my set up of the NMEA network along with considerable personal research. He also helped me solve the AIS not showing on the chart plotter from the VHF radio source during our cruise down the Lynn Canal.

[zuunami]

From what I see, if you start with a 4 port unit (they come with the terminators), you don't need any backbone cable, just the drop cables and battery cable. Sounds like a good way to go, takes up less space. Maybe a little more expensive initially than the "starter" units. But the starter units are only for one device, so you'd have to buy another drop cable and T for a second device. Haven't costed it out. Think I'll go with Garmin gear since the chartplotter is Garmin.

Then we could later add an extension cable going back to the stern. - Karen

[jkidd]

[LesR]

I installed one of these for my very simple setup (connecting an AIS transponder to two MFDs):

https://actisense.com/products/a2k-sbn-1/

Given that my power connection and components/sensors were all within a few feet of the helm, this provided a compact installation. Cost is approximately the same as a "starter kit" and four-way T connector.

Disadvantages are that it's not as flexible or extendable if you want to run the length of the boat.

[jkidd]

Simple Explanation

https://www.youtube.com/watch?v=11z81yPG_Mk

[zuunami]

jkidd, thanks, yes I've seen that video and others, the whole process is much simpler than I expected YAY I've looked at the parts you listed too, plus many others

The reason I may go piece by piece is that I can get 1' drop cables for the helm, and a 13' drop cable to go to the stern, by going directly through the Garmin site. The starter kit there, and on Amazon, has a 6' drop cable and 18' backbone cable. While I would be left with some Ts, I think I would just put in another multi port when we get to the stern. The price for all the cabling from Garmin would be about $200, while the Starter Kit, 4 multi port, and extra drop cable individually would be about $170. I have to do some measurements, but the shorter cables would be much cleaner and might be worth it. Thanks!

[ssobol]

I use the 4-port blocks. The power lead goes into one end and the other end is terminated giving you the full port availability (and only requires one terminator). If you expand you can get another 4 port block and a drop cable to connect the blocks. The terminator on the first block gets replaced with the drop cable and then the terminator is moved to the end of the second block. If you have all your NMEA 2K stuff near each other, the 4-port blocks take up less space and have fewer failure points.