[Bit of a Rant] Is the NMEA Corrupt or Incompetent?

[BrightSEALAB]

I'm leaning towards corrupt considering the financial traffic through the organization, but I'm willing to be convinced that they are simply the worst at what they do.

Here's my case for corrupt...

1- In 1985, the NMEA released it's first standard aimed at unifying communications between multiple brands of marine appliances. At that time a robust and well tested system of networking computers and peripherals together was already in existence in the form of 10Base2/5 Ethernet.

Cabling an Ethernet system was remarkably easy. Using inexpensive flooded coax wiring anyone could lay wire at custom lengths and adding nodes/peripherals along the backbone was as simple as cutting a wire and compressing a couple of CATV fittings. It looks like this...

The connector and cable types are readily available and cheap, as well as easy to work with and reliable. And it's capable of transmitting data between any station at 10,000,000 bps.

NMEA took one look at that and said, "Heck no. They're gonna get this..."

And then ... even when a device claims to be NMEA 0183 compliant, peripheral manufacturers still limit what data can be used from outside their brand and make connections complicated and expensive by not adhering to a standard single connector type. I still cannot replace my Raymarine Chart Plotter with a better brand without also having to buy a new Radome and buying a Tri-Nav NMEA 0183 GPS antennae provides my RM plotter basic functionality but loses some of the advanced functionality transmitted by the Raymarine brand unit (satellite visibility for example).

In a system touted as a communications standard the NMEA allows so much deviation that venders are just as able to make connecting devices from competing brands difficult to impossible and always more expensive.

Oh and NMEA 0183 send data at roughly 4,800 bits per second and there is no way for most peripherals to send data to each other without going through a 'Listener' device first.

2- By 1995 Ethernet had evolved into an even faster, more robust, easier and cheaper network physical layer. 10BaseTX could transmit 100,000,000 bits per second between anything connected to a switch or router. New devices just needed a home run to the hub. Weatherproof cabling was common and waterproof connectors were available and inexpensive. Cabling a small business with dozens of devices had a cabling cost of $100 or so.

So what does NMEA do, but take the worst aspect of 10Base2 and make it the central 'feature' of NMEA 2000. And pile on top of that, NMEA decides to go with a backbone and drop topology using multi conductor wires that cannot be built to size on the site by the owner installer. One must assemble their network infrastructure from expensive premade 'certified' little bundles of wire and connectors... $18 for a 20" drop wire. $20 for a t-fitting. And even then, most of the device makers have put their own special connector on their stuff and likely aren't letting 100% of other manufacturer's data translate.

3- Now the NMEA rolls out NMEA OneNet, and surprise!, It's based on the ethernet standard that's been available for 38 YEARS! And instead of promoting this, finally, as a system that can standardize and unify consumer marine installations, NMEA says that new equipment will still use all their old NMEA 2000 connections but be able to use the ADDITIONAL ethernet cabling to carry high bandwidth data like video and radar. Never bothering to say that it can also handle 100% of all data coming in and out of every piece of electronics on the boat through cheap industry standard connections and wire.

At every stage of this market development the NMEA has pimped consumer marine customers out to the manufacturers that pay their bills. And more like a Jon who's fallen in love with his hooker we continue to walk into a marine supply and ask, "Well is it NMEA [whatever] compliant?, I haven't caught Hep-C yet and have been meaning to try it."

Ok... that's enough for now...

[Pete7]

Yes, but what about the dividends for the shareholders of Raymarine, Garmin B&G et al, someone has to support them. They have taken a bit of hit lately. Selling drop cables at $20 each is highly profitable.

[ttex]

Solid rant. 9/10

[belizesailor]

True, it is a bit absurd the route the marine industry has taken and certainly appears manipulative. But remember it is an industry asociation so its not so surprising.

[BrightSEALAB]

Like... I was the tech nerd in school. Took a break from that, but then I see this 'newest' OneNet and it's ETHERNET!

I always thought of myself as pretty sharp with regards to technology, but I go to West Marine to buy a new chart plotter and they guy's like, there's no way your 10 year old Raymarine radome will interface with a new MFD unless maybe, MAYBE, if you get a new Raymarine chartplotter.

Then he barfs out strings of trademarked jargon.
Like, "So SeaTalk ng is the same as NMEA 2000?"
"Well it's compatible with N2K."
"Same connectors?"
"No body else will give you Raymarine SeaTalk connectors."
"It will talk to all my other N2K stuff?"
"They will share all NMEA2000 standard messaging."
"So it will use the data from my B&G Gauges?"
"As long as that data is standard N2K messages"
"Why wouldn't it be? Isn't that the purpose of having a Standard?"
...

[dfelsent]

What frustrates me is the paywall around getting a copy of the standards.
Really really expensive.

[Dave Lochner]

NMEA didn't develop the standards, they basically borrowed and modified the standards from the auto industry. NMEA is based on the CAN bus.

The Marine electronics industry then changed the names to protect the innocent buyer by calling the various networks SeaTalk, Simnet, and who knows what else.

https://en.wikipedia.org/wiki/NMEA_2000

[Hermia II]

Do compare apples with apples. Question for you, whar’s the price of a IP67 class RJ45?

[Hartleyg]

First, let me address some of the statements made here:


1. BNC connectors are NOT waterproof (N connectors are, but not BNC).
2. "Flooded coaxial cable" (which would be potentially waterproof) is extremely uncommon and quite difficult to work with. Non-flooded cable is easy, but flooded is NOT.
3. When NMEA-0183 was developed (not released), 10Base2 did not exist!. 0183 is based on RS-232, with some adaption, but it is not really a "data buss". Yes, it's a PITA
4. I am not a NMEA insider by any means, but I suspect that one reason they did not examine a coaxial cable based standard is the hazard of water intrusion, which is extremely difficult to detect and localize. They instead use wire-based standards which are likely only to experience problems at terminations.
5. If you think "flooded coaxial cable" is a good solution, why is it totally non-available on the RF side for antenna lead-ins? It's because it requires seriously PITA work to put on connectors (of any kind).

6. Dave Lochner is correct - the NMEA 2K standard is indeed based on the automotive electronic CAN buss - a highly robust design intended for the rather hostile environment of an automobile! If there is any "magic" in the NMEA version, it is the data Sentences contained within it, which differ dramatically from those used in cars.



The issue of expensive Standards documents exists in EVERY industry that constructs its own. They have to pay for the effort and expense of creating them somehow. I suppose we could ask the .gov to take over, but would you rather have bureaucrats designing Standards or people within the industry?
As an example, the absolute Standard for ANY electrical installation is the National Electrical Code - a Standard developed by industry (and often endorsed by government) - they aren't free, though their cost is lower than Marine Standards mostly because they sell tens of thousands of copies every year. How many copies of the NMEA or ABYC Standards do you think would be purchased every year?

The folks who do the actual work of building standards are generally volunteers, btw - they may get reimbursed for expenses, travel, etc., but they don't get paid - at least by the NMEA. The paid employees do the document formatting, editing, etc.



What the manufacturers do after the Standard is issued is NOT the problem of the NMEA.


Hartley
S/V Atsa

[EarlWer]

Originally Posted by Dave Lochner

NMEA didn't develop the standards, they basically borrowed and modified the standards from the auto industry. NMEA is based on the CAN bus.

The great thing about Standards... There are so many to pick from...

[EarlWer]

Originally Posted by Hermia II

Do compare apples with apples. Question for you, whar’s the price of a IP67 class RJ45?

https://www.l-com.com/ip67-waterproo...c-wp67-rj45-dc

About $13 for each end... I'm sure there are cheaper ones out there...

I think people would not mind too much if they standardized on the IP67 ends and allowed people to make their own RJ45 cables.

I make RJ45 cables all the time. Adding a IP67 connector to each end would be acceptable, even at $13 each.

[Jammer]

Originally Posted by EarlWer

The great thing about Standards... There are so many to pick from...

You're (mis)quoting Andrew S. Tanenbaum.

[Narfi]

We have upped our standards, so up yours.

nothing useful for me to add other than my tangle looks cleaner than that tangle and I don't know what I am doing.... I think in any situation you can find a bad picture but it probably wont represent the reality......

[moseriw]

As far as I reckoned NMEA is nothing but a protocol so if you want you can send your bits and bytes over ethernet or any-net. OK they standardized the sensors to feed their signals with special voltages, ohms, amps so the sensor are not compatible to the given net.

So it could be up to you to make an interface with POE to translate all rubbish protocols to the electrics of ethernet. A protocol transation itself is not really required.

[goboatingnow]

Personally after decades in the CAN bus industry , I’m glad that NMEA 2000 is can and not Ethernet

Ethernet has its place but running cables up the mast to a wind wane isn’t one of them.

Secondly you have to remember that nmea 2000 is “technically “ designed to be self installed , that’s means by people that definitely can’t crimp on RJ45 connectors. That explains the pre made cables

The fact is if you want to roll your own can backbone it’s easy if you know what you are doing.

The issue of the openness of the protocol is moot after all NMEA is just that , a collection of manufacturers.

As for inter connectivity , see Windows /Linux/mac os for incompatibilities.