NMEA 2000: what can I actually display?

[iNavX]

For more clarification on what iNavX specifically will display, here is the page from the manual showing the 0183 and NMEA 2000 sentences it will recognize and display.

So if your N2K to Wifi bridge can relay these, it will show them.

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[DanielI]

Originally Posted by a64pilot

You sail on a lake on a small boat, and don’t need a plotter.
You have no need of NMEA 2000 anything, except as a toy, it’s up to you to decide if it’s cool or toy value is worth it.
I’d tell you to put the money in a new sail, or a sail you don’t currently have.

Not meant to belittle you, I have all instruments networked, and don’t “need” them, I was replacing old ones anyway so why not?

Agreed. This is not about need.

Perhaps more context is helpful. Navajo Lake on the NM/CO border is about half the size of Lanier, and the boat is a 89 Catalina 30. As far as I can tell, all the instruments are original, and the SR Mariner Nav-10 isn’t working. The problem may be (in part) wiring issues in the mast.

The only thing I really *need* is depth; the water level varies around the sunken islands around here too. I’d like the four functions (depth/speed/wind speed & direction) from my current (broken) system, and I’m likely to need to replace at least the display, if not all the transducers. (My research on new transducers versus a analog-digital converter is still inconclusive; advice on that score is also welcome.) Paying the cost of the basic four is worth it to me.

As it happens, I’m also putting in solar, and the Victron controller, which seems like one of the best options out there, claims to have NMEA 2K support. Which is why I’m wondering would I actually be able to display the data, and if so, where? I agree that seeing it at the helm is not the most useful thing, but as I’m not putting in a chart plotter, the only other place would be to get it onto a tablet.

I’m not going to pay $Ks for the privilege, and I’m not going to spend a fortune upgrading all my engine meters, but if there is a solution that is not too expensive, I could have the flexibility to put other future upgrades on the system, if I set it up correctly now.

FloatHub looks cool, but investing in 0183 now does not seem like a good strategy for future proofing. The XB-8000 seems like overkill for me, although I would be tempted if I was sailing off coast.

Thanks for all the helpful input. Online reading varies between breathless brochures (“NMEA 2K makes everything work together and solves all your problems instantly,” I’ve worked with too many computers to believe that) or goes into highly technical details about how to connect this specific devices via this converter, with nothing in between.

[OS2Dude]

The original transducers from 1985 are still in place, at least until I get a chance to haul out for a bottom job. The original displays were burned by the sun and the cables (with three sections each connected by RCA jacks) were terribly corroded. I ripped the cables out and will do the same to the transducers when I can.

There are several analog to NMEA2K devices out there. Tank Levels, Rudder Angles, etc. So you don't have to spring for a total replacement of existing analog sensors.

To the trolls who say you don't N-E-E-D NMEA2K: Yeah, your right. I don't NEED a windex, telltales, compasses, VHF, charts, engine, electricity or most anything besides a hull, rudder, sail, mast, halyards and sheets. So what's your point?

[muttnik]

Originally Posted by iNavX

So if your N2K to Wifi bridge can relay these, it will show them.

Can you clarify how iNavX expects to receive "N2K" data? I'm guessing the chetco "seasmart" DIN sentences or the PGN sentences used by the miniplex but when I tried asking your support this I was told it was a programming secret that couldn't be shared.

[muttnik]

In the absence of a reply from the iNavX account, a lack of an informative response from their support people....does anyone know how iNavX expects to receive "N2K" data over wifi (e.g PGN sentences, raw binary, whatever?).

There doesn't seem much point in having a feature that you don't tell people how to use...

[OS2Dude]

Originally Posted by muttnik

In the absence of a reply from the iNavX account, a lack of an informative response from their support people....does anyone know how iNavX expects to receive "N2K" data over wifi (e.g PGN sentences, raw binary, whatever?).

The transmission method is unimportant in the end. Wi-Fi transports data in an IP protocol over radio, the same as if you had a hard wired ethernet. The data going through the ethernet is not changed at the end-point from what it was at the input point. (Ethernet would be useless if it changed the data that it carried.)

N2K is a binary protocol with predefined sentences. 0183 is a text protocol with predefined sentences.

Not sure why you really care. If both devices are licensed N2K, then they will talk to each other. (Assuming they have not added their own proprietary 'extensions'.)

[muttnik]

Originally Posted by OS2Dude

The transmission method is unimportant in the end.

N2K is a full stack protocol and it doesn't involve 802.11 which is why you won't get any "NMEA certified" N2K-over-wireless products. You're assuming they're ditching any datalink layer info and bundling selected application layer binary data into an IP packet (and one question is what layer 4 protocol would they choose with that?)

A little investigation however suggests that that isn't what they're doing:
From this:
http://inavx.com/wp-content/uploads/...the-Basics.pdf
we see they say:

NMEA 2000 support: Chetco Digital Instruments SeaSmart WiFi OR
Combine an Actisense NGW-1 ISO with one of the above multiplexers

Now the NGW-1 is a different kettle of fish from the NGT-1. The NGW-1 simply converts N2K to NMEA-0183. The Chetco thing though converts N2K to a special NMEA-0183-styley format (which they publish and isn't "secret"). That they're using this seems supported by this panbo article:
https://www.panbo.com/open-n2k-to-wi...t-instruments/

However, Shipmodul's miniplex3 multiplexers do a similar thing with what looks at first glance to be a different -0183-styley encoding.

Originally Posted by OS2Dude

Not sure why you really care.

Because if I can send "N2K" data to iNavX and have it displayed, that's a reason for me not to renew my Navionics subscription and buy iNavX instead. However I have no intention of spending €400 on a commercial wifi multiplexer when I already have an actisense NGT-1 and a raspberry pi and an hour's coding would allow not just me, but anyone I share my code with, to send data in any of the formats suggested.

The response from iNavX hasn't encouraged me to shell out the cash for a copy just to experiment.