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Old 07-07-2015, 16:12   #1
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Raymarine and NMEA for Dummies

So I bought a new boat. And now I have to learn. And learn. And learn...

I am ok at computer networks but know absolutely nothing about marine ones and I think my assumptions are getting in the way.

I have:
Raymarine E 80 chartplotter
Raymarine radar (no idea of the model)
Raymarine 60 depth meter, wind instrument and knot meter
Raymarine ST 7001 auto pilot with remote
Matrix AIS GX2150 vhf with RAM

Radar works great on chartplotter. AFAIK the auto pilot does not speak to the plotter and I know for a fact that the vhf is not hooked up to the GPS (stupid alarm).

Before I go tearing everything apart and tracing wires like a madman I wonder if anyone can explain the likely network topology. Is there an equivalent of a hub or switch? Is everything just daisy chained? I have already found the requisite dead wiring from old installations, which always adds to the joy.

I would like to hook the AIS from the radio to the chartplotter. It seem ridiculous that this wasn't already done, but maybe I am missing something. I am indifferent if I get the autopilot talking, but for completism I should at least look at it.I 've dug through the manuals, but they are making some assumptions about my knowledge that just leave me confused.

So, who wants to give me a quick lesson in NMEA and/or Seatalk?
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Old 07-07-2015, 21:35   #2
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Re: Raymarine and NMEA for Dummies

Seatalk is a very simple network electrically. There are 3 wires as follows:

+12V (red)
Data (yellow)
Ground (green or black usually)

All 3 wires are connected in parallel. Each Seatalk device knows how to cooperate to use the single data wire to communicate with all the other devices on the network.

NMEA is not a network like Seatalk. It is just a way to connect 2 devices together. There are 2 TXD wires and 2 RXD wires in an NMEA connection. The two TXD wires (+ & -) of one device connects to the RXD (+ & -) wires of the other device. If the devices need to talk back and forth then the same thing happens in the other direction. You generally don't connect more than 2 devices together with NMEA. There are some NMEA multiplexer/splitter devices you can buy that enable feeding NMEA data to/from more than one device but these are specialized and probably not needed in your situation.

Your VHF radio has GPS built in already if it has AIS. Check the manual if it needs a GPS antenna. Maybe the previous owner did not hook it up. AIS will not work without GPS. So get that working first.

Then check the manual if the E80 chartplotter accepts AIS. If it does find the NMEA output from the radio that is set for 38,400 baud. That is the standard AIS baud rate. Connect the +/- outputs of the radio to the appropriate NMEA +/- inputs of the E80 and AIS should magically appear on the screen.
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Old 07-07-2015, 22:50   #3
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Re: Raymarine and NMEA for Dummies

the chart plotter might not take nmea at 38,400 baud to hook the ais up. you'd have too look at the serial settings and see if you can change it from 4800.


either way you can feed gps to the radio (no they are not built in just because they have ais). as it'll take gps at 4800 or 38.400


I'm guessing the pilot is seatalk?.. and can probably just join into the system. the screen may have pilot control turned off in the menu. there is an option for that
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Old 07-07-2015, 23:01   #4
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Re: Raymarine and NMEA for Dummies

I found these two resources to be useful:

NMEA Revealed

Boat-Project.Com - Using NMEA 0183 With Modern Electronic Equipment

- Rusty
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Old 08-07-2015, 04:28   #5
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Re: Raymarine and NMEA for Dummies

Good summary from transmitterdan. The E80 classic does indeed accept AIS but you might want to ensure it has been upgraded to the last firmware they made for it.

Should probably be mentioned that there are at least 3 main flavours of "seatalk" (we won't mention seatalk-2), all of which the E80 accepts. "Seatalk" (aka seatalk-1" is as described by transmitterdan and what the ST60 instruments and that autopilot would normally be networked with. "SeatalkNG" is a proprietary spin on NMEA-2000. It has different connectors to NMEA-2000 but it's compatible with it (via an adapter). It also has an additional wire for carrying seatalk-1 data. The connection between the radar and the plotter will depend on whether it's digital radar or analogue: The E80 supported both. If digital, the bandwidth for imaging is too high for SeatalkNG (way too high for seatalk-1) so the connection will be "SeatalkHS". This is fast ethernet at layer 2 so yes, there may be a switch in there but most likely it'll just be a crossover cable.

NMEA-0183, as described, is a serial line protocol and what you're dealing with here. NMEA-2000 is the "modern" NMEA protocol: based on CAN, it's pretty much 1980s automobile networking. The E80 can also work with that but none of the items in your list use it. There is also an NMEA-2000-over-IPv6-over-ethernet standard called "OneNet" which should be ready umm....Real Soon Now (is there a tumbleweed icon I can insert here?) but there isn't even a standard yet, never mind products.

Coming from a computer networking background you may be surprised to find that the NMEA produce closed standards. Eric Raymond has done a lot to publicise the contents of NMEA-0183 (see rgesner's link above) to the extent that I don't believe the famously-litigious lawyers really pursue people using it without a licence any more. Partially as a consequence of that, the application layer of NMEA-0183, transmitted over IP, is used as the de facto (non-) standard data communication method for many marine applications, including OpenCPN.

All the Seatalk protocols are Raymarine proprietary, but much of seatalk-1 has been reverse engineered and documented by Thomas Knauf and others

Now as a computer networking person your next question will undoubtedly be about getting all those data into your laptop.....
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Old 08-07-2015, 09:26   #6
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Re: Raymarine and NMEA for Dummies

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Originally Posted by rgesner View Post
I found these two resources to be useful:

Boat-Project.Com - Using NMEA 0183 With Modern Electronic Equipment

- Rusty
Awesome link , thanks!

And thanks everyone else. This at least gives me something to go on as I start tracing wires. The rat's nest behind the electrical panel is intimidating to say the least. The whole mess cries for some standardization doesn't it. Reminds me of the back of a computer in early 90s: serial cables, 10baseT, coax ethernet and more specialized plugs than you could shake a stick at.

And I guess I go back to the manuals. At least with the explanations they will make a bit more sense..

One more quick question, is there an equivalent standard cable (like cat 5 or Cat 6e) for hooking up radio to plotter etc. or is it more a matter of longer run=larger gauge?
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Old 08-07-2015, 11:34   #7
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Raymarine and NMEA for Dummies

For NMEA 0183 connections cat-5 cable works ok. There is no standard connector. Screw terminal blocs are ok as are Euro style blocks with spring compression terminals. It is best to have a shield at only one end of an NMEA cable connected to 12V ground. Having a shield connected at only one end helps avoid ground loops.
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Old 08-07-2015, 11:52   #8
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Re: Raymarine and NMEA for Dummies

If you're new to NMEA, It's important to know that there are TWO totally different NMEA standards:

:: The original NMEA 0183 standard, which is what everyone has discussed in this thread and what your equipment is.

:: The new NMEA 2000 (sometimes called NMEA2K or N2K, also the same thing as SeaTalkNG (Raymarine's version) and SIMNET (Navico's version) except that they use different connectors.

It's important to know that NMEA 2000 is totally different than NMEA 0183 and SeaTalk is totally different than SeaTalkNG.

Just about all new equipment is NMEA 2000, so don't buy any of it thinking its going to be compatible with your existing gear because it says NMEA on it. There are various adapters from NMEA 0183 to NMEA 2000 (and SeaTalk to SeaTalkNG) that you'd need to use.

Good luck!
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Old 08-07-2015, 12:16   #9
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Re: Raymarine and NMEA for Dummies

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Originally Posted by Macblaze View Post
One more quick question, is there an equivalent standard cable (like cat 5 or Cat 6e) for hooking up radio to plotter etc. or is it more a matter of longer run=larger gauge?
For NMEA-0183 you theoretically want tinned, stranded, shielded AWG 22 twisted pair. In practice for the short-ish runs you get in the average sailing boat DIY-ers tend to use all kinds of stuff.

Seatalk-1 I don't know the exact specs. Officially you were supposed to buy ready made cables with the connectors on in fixed lengths. There are two types of connectors for seatalk-1, the older ST50-styley round ones (which I have) and the "newer" ST60 flat style ones which you doubtless have. The actual cable I've seen two types: 3-core and (more recent???) 2-core+shield. Don't know if the cable spec changed with the connectors (anyone else?). For many obtaining the connectors is a challenge. You can cadge some old ones and connect them up to longer cable. I discovered that the round types are actually available (not branded as "seatalk"): Amphenol BD series(???). Don't know about the flat type.
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Old 08-07-2015, 12:52   #10
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Re: Raymarine and NMEA for Dummies

Just an FYI. If you do hook the VHF to the Chartplotter be aware that your baud rate MAY need to be set at 38400. AIS is usually much data to send over the standard 4800 baud rate.

Based on your description above... I beleive you will only need to run 4 wires between your CP and VHF. 2 wires from NMEA out of the CP (goes to NMEA in on VHF) and vice versa. This should allow AIS to show up on the CP and the VHF to get GPS data over NMEA. It will also give you DSC functions on the CP.
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Old 08-07-2015, 13:24   #11
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Re: Raymarine and NMEA for Dummies

Couple of thoughts. First thing I would do is look in the back and see if you have any NMEA2000 T's in the system. If not, then you are NMEA0183.

ST60 instruments you have are SeaTalk1. That can be linked via NMEA0183 wires. You can use the flat ST1 connectors, or just wires with very small connectors on the end. You can also convert ST1 to STng - which is the same as N2K - with a Raymarine converter. That way your ST60 data can be converted to N2K data, if you have that network.

You're tackling it correctly. Start tracing lines/wires. Get some white tape and start labeling the lines. Make a diagram. Then it will probably become obvious how things are hooked up. Then if not working, it might be a baud rate issue or a wire not hooked up.
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Old 08-07-2015, 15:02   #12
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Re: Raymarine and NMEA for Dummies

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Originally Posted by travellerw View Post
Just an FYI. If you do hook the VHF to the Chartplotter be aware that your baud rate MAY need to be set at 38400. AIS is usually much data to send over the standard 4800 baud rate.

Based on your description above... I beleive you will only need to run 4 wires between your CP and VHF. 2 wires from NMEA out of the CP (goes to NMEA in on VHF) and vice versa. This should allow AIS to show up on the CP and the VHF to get GPS data over NMEA. It will also give you DSC functions on the CP.
I believe this is correct. I just went through this with my E80 and a new Standard Horizon VHF with AIS. The VHF has an internal GPS, but it will also accept GPS data from the E80. The E80 baud rate will need to be set to 38400 to accept AIS from the VHF. Mine was all NMEA 0183
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Old 08-07-2015, 19:36   #13
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Re: Raymarine and NMEA for Dummies

We have similar equipment on our boat E-80 chart plotter, depth sounder, etc.
The earlier comments are way above my pay grade, so I would follow their advice and see if you can get most things working without spending lots of money.
I also have Raymarine AIS, but it is very touchy, alarms go off all the time and there are at least 3-4 great iPAD apps - like Marine Traffic or Garmin Blue water that are dirt cheap and do a much better job of showing your position are really excellent charts, and Marine Traffic will show you all the boats with AIS, their speed and heading. Raymarine AIS is very sensitive to voltage (and it draws a lot of power) so I stopped using it because the iPAD apps are infinitely better.
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Old 08-07-2015, 21:02   #14
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Re: Raymarine and NMEA for Dummies

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I also have Raymarine AIS, but it is very touchy, alarms go off all the time and there are at least 3-4 great iPAD apps - like Marine Traffic or Garmin Blue water that are dirt cheap and do a much better job of showing your position are really excellent charts, and Marine Traffic will show you all the boats with AIS, their speed and heading. Raymarine AIS is very sensitive to voltage (and it draws a lot of power) so I stopped using it because the iPAD apps are infinitely better.

I would get your Ray AIS to work, so you can track ships real time. I would not trust Marine Traffic app that gets data from internet. Lots of discussion on this on another thread. One member showed significant difference in location of his boat on MT vs real-time AIS. I travel ICW a lot, and vessels can converge very fast. Why I have an AIS transponder.
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Old 09-07-2015, 02:39   #15
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Re: Raymarine and NMEA for Dummies

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I would get your Ray AIS to work, so you can track ships real time. I would not trust Marine Traffic app that gets data from internet. Lots of discussion on this on another thread.
+1. Active thread on the OpenCPN forum but there have been a few others. If using your AIS with an E80 make sure the firmware is updated to the last revision: That's basically just downloading a file onto a CF card to put into the plotter and following the firmware upgrade instructions: not as complicated as it sounds.

The CPA alarm distance can be reduced or alarms turned off altogether on the Raymarine plotter. My mooring used to be in Portsmouth harbour (UK) where there was constant heavy traffic so I'd have the alarms off. In fact I had the AIS off almost all the time: I only really find it useful crossing traffic which travels on a straight-ish course (such as the English Channel), certainly not in heavy traffic areas where the course of large vessels is determined by irregular geography (like the Solent).

If DougAnnapolis likes to use AIS but prefers iPad navigation to using the plotter, consider converting the AIS data from the Raymarine AIS to wifi and using a nav app like iNavX which can use wireless AIS data. Commercial serial-to-wireless boxes tend to be several hundred bucks but cheaper alternatives include using a laptop, a single board computer like a raspberry pi, or cheap ebay serial-to-wifi (or serial-to-ethernet if you already have a wireless access point).
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