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Tenedos 03-04-2015 10:57

Best way to integrate NMEA into iAIS
Ahoy sailors,

I have recently bought a Digital Yacht iAIS to play with and learn some more on marine electronics (AIS, NMEA, integrating a chart plotting software, etc).

iAIS has a means of getting NMEA data in and multiplexing it and sharing over WiFi for iNavX running iPad/iPhone etc.

I am trying to figure out the best place to get the NMEA data from. Before I start pulling apart my boat, I wanted to ask to more experienced sailors.

I have a few hopefully basic questions to start with:
  • Should I expect to find an NMEA bus somewhere that integrates different components or will individual components be directly linked? (I have a sounder, autopilot and wind speed/direction unit. All Raymarine and the displays are on the vavigation console by the helm)
  • What is the best place to make the link? Obviously, I prefer not to run extra cables if I don't have to. Not sure if this is possible or feasible.
  • Anything else I should watch out for?
My boat is a Catalina 320 from 1999.

Thanks in advance for pointers.

barnakiel 03-04-2015 11:09

Re: Best way to integrate NMEA into iAIS
It all depends on your hardware.

If your multiplexing device is the iAIS, then check if it is NMEA 183 or NMEA 2000 (N2K) input. If it is 183 then you can only multiplex one talker per each physical line (read this as one set of data, e.g. GPS data). A N2K input will allow multiple talkers, by its own design.

Then access the data at the point that is convenient (mostly: NMEA OUT of any device) wire it into your iAIS and then you get multiplexed data (AIS data and e.g. GPS data) on this device's (iAIS) NMEA OUT.

There is a zillion of ways to approach this cat and it is all hardware dependent.

As a side dish I will say that if you do like playing with interfaces / NMEAs and data streams then given the way the gadgets seem to be headed, I would suggest wiring all your data into a wireless NMEA/N2K multiplexer. I say this because I see more and more devices getting rid of cables and I believe this is where the future is.


jstevens 03-04-2015 11:28

Re: Best way to integrate NMEA into iAIS
+1 on Barnakiel post.

Since you say all your instruments are Raymarine, and assuming they are of the ST60/ST6000 vintage, then you likely do not have an existing NMEA 183 or N2k network. It is likely everything is connected via SeaTalk. If your Raymarine stuff is fairly recent it could be SeaTalkng, which is the Raymarine version of N2k. I think it still requires an adapter to work with generic N2k.
Once you have an inventory of the Raymarine models then contact your AIS rep to find out the best way to interface it. Best to contact the Raymarine forum for input as well.


hellosailor 03-04-2015 12:35

Re: Best way to integrate NMEA into iAIS
Raymarine (Raytheon, whatever) are good stuff but well known for requiring their own Raytalk (Seatalk) protocol, probably no NMEA to be found on your boat.

You'd need to check that on the instrument menus (for an NMEA option) or by looking up or calling about the specific models.

There ARE "Raytheon to NMEA" converter boxes on the market, but you may not like the price. Might be simplest to buy a GPS, or a GPS plotter, with the right options to plug into your AIS, and leave the Ray-stuff in happy isolation. And pretty much no big loss to do it that way.

Mycroft 03-04-2015 13:13

Re: Best way to integrate NMEA into iAIS
Forget NMEA 2000 - the iAIS is a NMEA 0183 box. So minimally, you need to connect an 0183 GPS device to it. Best would be to connect to a chartplotter both ways with 0183. Then you should get all the data the chartplotter has onto your iPad etc.

Do not use an ordinary splitter with your VHF antenna. You could fry the iAIS the first time you press the mic button. You need a separate AIS antenna or a special splitter that cuts the AIS out when the mic is pressed. See Vesper Marine's splitter.

barnakiel 03-04-2015 16:13

Re: Best way to integrate NMEA into iAIS
If you are Ray dependent then there is a SeaTalk / NMEA combo box that will OUT all data on SeaTalk (and NMEA) OUTs.

There is also a neat SeaTalkng / N2K adapter.

And you are set.

But in such a case I would actually stay on the Ray bus and add the AIS signal to it.

PS You do want N2K or STng if you have plenty of data, I think 183 will not provide enough band / speed for too many instruments talking to each other. That's why N2K substituted NMEA 0183 (I believe).

So my now incarnation of the earlier advice is to stay with Ray, add AIS to it.


muttnik 06-04-2015 02:02

Re: Best way to integrate NMEA into iAIS
NMEA-0183 which is what the auxiliary input to the DY iAIS takes isn't a bus protocol: it's simply point to point so no, there won't be a bus you can trivially connect it to. You don't say what model instruments you have but if they haven't been upgraded since 1999 they will most likely be connected via Raymarine's proprietary seatalk (aka "seatalk 1") protocol which *was* bus-oriented. To take a feed off that you need something which converts between seatalk-1 and NMEA-0183. Some of Raymarine's instruments do that. If you have an ST60 multi display, I believe that has an NMEA-0183 out (owners please correct me if I'm wrong). You don't mention a chart plotter (I assume you don't have one) but most Raymarine chartplotters which take seatalk in would convert to seatalk out (my old navcenter ST50 did, my newer C90W does). Raymarine also used to make a converter box, the E85001, no longer in production but which is still available on ebay etc. Take the wires from whatever you use to convert to the iAIS.

"Seatalk NG" or "STng" is Raymarine's newer bus-oriented protocol (repeat use of "seatalk" for different protocols can be confusing :-) which is a slightly different animal but if the instruments are from 1999, they likely won't use that.

Take a read of the stuff on networking on Raymarine's site and try and work out what you have.

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