NMEA networking between chartplotter and radio

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
 
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
 
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.
 
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
 
zuunami":3ik8ewcq said:
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
Click to expand...

I haven't seen any of the 4 port tees that come with the terminators. The starter kit is here.
https://www.amazon.com/Garmin-010-11442 ... 147&sr=8-4

and the 4 port tee is here.

https://www.amazon.com/4-Port-MultiPort ... pons&psc=1

You will have some parts left over to expand when you need to. If you buy the parts separate it will cost more.
 
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, 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!
 
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.
 
ssobol":1woat23z said:
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.
Click to expand...

I have to disagree with leaving one of the terminators off. The terminators measure 120 ohms and they are in parallel in the circuit. So when both terminators are in the circuit you will measure 60 ohms. Your network should measure 60 ohms when resistance tested. 120 ohms means there is only 1 terminator, and 40 or less means there are too many. Not having the right resistance could leave having intermittent problems crop up in the future. The Nmea 2000 spec calls for both terminators to be in place.
 
Everything I've read or seen says that both terminators are needed.

On another note, I knew when I started this research that the Garmin chartplotter and SH VHS with ais could be directly wired together. I thought that a backbone would be great to start with to then attach other sensors/devices along the way. I'm discovering that the Mercury motor unit is $600 (if our 2006 40 hp is even capable), and must be programmed by a dealer (3 hours away through the mountains). Well, how about a battery sensor to easily check the charge, not finding anything. An additional monitor just for the AIS receive would be nice, but we only have so much room on the helm dash. A wind sensor, no, it's windy here usually.

So, while it's been fun and informative, and I'm sorry but very grateful for everyone's time, now I'm not sure it's even practical for us! lol

Karen
 
Well, hooray, I finally found a couple of reasons to do a nmea 2000 backbone, (and I just wanted to anyway but couldn't find a reason to justify it:)

1. The wiring that would connect the garmin chartplotter to the SH GX2400 radio (to access the radio's AIS receive) are really too short to reach each other and would need splicing.

2. The SH radio uses a cable to transfer firmware and software updates (unlike the garmin chartplotter that uses a micro sd card). Since I'm the only person in the world that doesn't have a laptop, that means I need to transfer the data from my PC to the radio through a cable, requiring that I set up the radio next to my computer with a battery. Hmm, not sure what SH is thinking :) With nmea 2000, I can at least easily disconnect the radio and bring it inside to do any updates. Maybe I'm missing something with the SH, but tech support said the radio needs to be connected to power to do the updates, so I'm not aware of any other choices. Tech support has gotten back to me in 24 hours with two emails I sent, so I have to give them major kudos for that.

3. If we want to bring the units inside for the winter, we easily can.
 
Well, contrary to the advice of Steve-in-SEA who started this post, I decided to go with Ancor instead of Garmin nmea 2000 components because the Ancor cables were the length I needed to make a less messy wiring conglomeration in our small 16. So far, no luck, so I have to go back and check all my connections. I have a 4port block backbone, with Ancor's T power connector that goes on the end, then terminators on each end. Then drop cables to the chartplotter and to the VHF. For future expansion, we would add cabling to the other side of the power T.

One of the things I noticed in looking again at jkidd's diagram earlier in this post, and elsewhere, is that it doesn't show any separate power connection for the chartplotter or the VHF? Maybe that's my problem, I have them both going to power...

I'll recheck all my connections, maybe it'll magically work when I turn everything on again tomorrow. Or, there's always nmea 183 :)
 
It all works perfectly now that I found my stupid mistake, which is too embarrassing to share. Ok, I will - I was so intent on cleaning up the wiring and making it all neat and tidy that I missed connecting the Garmin drop cable to the backbone :)

I apologize for the post :(

I have to say that I love the Garmin, it's so easy to use, and a 9" screen is so worth it.
 
Having re-read the thread, I see that I was contemplating getting an AIS transponder (for the Chiton not the Limpet. That's been done.
Part of the reason was that I could get my radio (GX2400) to show AIS targets on the Garmin MFD using NMEA 0183, but not when I changed to my new NMEA 2000 backbone. It didn't really matter because my new transponder gave me AIS targets on the Garmin.

But it raises two questions (projects). Can NMEA 0183 and 2000 be used at the same time? I could simply reconnect the VHF via 0183 and, should the AIS transponder go down, I'd still have another source for AIS (receive only) via the VHF 0183.

Second, I thought that I had read somewhere that it was possible with a VHF/MFD connection to see an AIS vessel on the touch screen, touch it to get vessel info and MMSI (which I can do), but also have an option to call the vessel using the touch screen to hail the vessel via the VHF. Does this sound like something my system could do? Maybe it was just in a dream. It would save having to read the MMSI off the screen and enter it into the VHF, or get the vessel name from the screen and then find it in the list of AIS targets on the radio, both of which could be clunky and time consuming. Getting an instant vessel name and quick radio contact would be great just via the Garmin screen.
 
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