So I may be on semi vacation, and having a time, but I’m still looking forward to getting back to the lab where the network of NMEA instruments recently grew to include Furuno’s and Simrad’s latest. Check out the big picture here . I’ll be writing a comparative overview on these five brands soon after I get back, and I’m trying to sort out factors to check out. So far I’ve got:
While the extreme N2K cable mixing and daisy chaining shown yesterday did seem to work OK in lab conditions, here’s a smarter approach for a serious boat system (bigger here). The main change is that every cable section possible is NMEA “approved,” which means it’s built to the ODVA DeviceNet standard (that NMEA borrowed). While every N2K cable and connector seems vastly superior to the fine-gauge 0183 wires, crimp connectors, terminal blocks etc. they replace, DeviceNet seems the best of the lot—particularly in terms of interference protection—and I don’t see that it’s significantly more expensive or harder to work with (especially given the growing number of install doodads, even breakout boxes).
The Panbo lab is a good place to push things in ways a smart installer never would; in other words, do not try this—bigger picture—on your boat! What I did here was to purposely break about every NMEA 2000 “recommendation” I could.
Thanks to a loan by the good John Gass of his test SeaTalk wind sensor, I’ve now got a Raymarine ST70 Wind Pod plugged into the lab’s ever expanding NMEA 2000 experiment. The Pod can supposedly gateway “any standard Raymarine wind transducer” onto SeaTalkNG and it was pleasing to see that it does indeed put out a standard NMEA 2000 Wind Data message (PGN 13036). All the displays read it fine. And, as suggested above, the ST70 has splendid graphic calibration and diagnostic facilities that work with the pod and sensor. You can correct the vane offset and apply a speed correction factor, either via an underway guided routine or manually. The ST70 can also query the components for model and serial numbers, software and hardware editions, even node voltage.
So I hope yesterday’s goofy contest made a point about Raymarine’s STng cabling system. I do think the design has merit, particularly for production boat building, and there’s more of interest, like heavier gauge power wires, that I’ll get into eventually. But today I’m going back to the larger point that NMEA 2000 cabling is not that big a deal. As noted earlier in these ST70/STng experiments, the data flows easier than one might think given the different connectors and network names. What really counts is that the desired data is sent and received. I learned that vividly when the first Garmins could hardly understand any N2K PGNs (messages), despite having a standard NMEA 2000 connector, and now I’ve stumbled on an ironic reminder.
I’m on deadline today, and may find no more time for posting, but here’s a puzzle to ponder. Those two male female connectors above are unique to Raymarine’s SeaTalkNG (or STng) version of NMEA 2000 cabling. The white version is on both ends of every “spur” cable that’s used to connect devices to the backbone—or to daisy chain one device to another—and the blue version is on both ends of every backbone segment. So why in tarnation does one have six pins and the other five?
Another sign that 2008 is the year of NMEA 2000? Airmar tells me that orders for its various N2K Smart Sensors—depth/speed/temp info online now, high performance PB200 Weather Station plus GPS/compass and plain compass coming “soon”—are way ahead of projections. Plus the company is now offering “a full-line of affordable, NMEA 2000 certified cables and accessories.” I’ve got some samples in the lab, bigger picture here, and the cable is a wee bit thinner than the gray Micro size I’m familiar with—a little less individual wire insulation, I think—but otherwise seems very similar. The cabling source is LTW, and Airmar says it’s “been rigorously tested to comply with the NMEA 2000 standard.”
Ah, yet another doodad useful for installing a NMEA 2000 network, an economical one too. If used to the max, Actisense’s brand new QNB-1 “Quick Network Block” takes the place of 6 regular N2K tee connectors, 8 cable connectors, and a separate power supply (like most of this). Plus all the N2K cable ends run into it can be run through smaller holes and tighter spaces than even those skinny SimNet connectors, and they can be cut to fit perfectly. And I don’t see why it can’t be used with proprietary flavors of N2K cable too (the possible exception being SimNet because it lacks a distinct “shield” wire). The QNB-1 even includes 4 amp blade fuses for each side of the backbone, and LEDs that indicate power on/off/reversed and data activity, and it will retail for about about $146 (available in the U.S. from Gemeco).
Chris Witzgall from Apex, NC, recently wrote {slightly edited}:
Your site has been invaluable as I get back into boating after a long hiatus, and work out the electronics for our new-to-us Westerly Fulmar sailboat. I have settled on NMEA 2000. Our needs are relatively simple; here is what I have**, or will have*.
Ben E | Permalink | Comments (25)
I thank Dan for yesterday’s NMEA 2000 homily (more guest blog entries welcome!), but I do want to play devil’s advocate. I’ve had my head in the Simrad Yachting 2008 catalog today (unfortunately not online yet), and I’m ever more impressed with how thoroughly the company has adopted its SimNet version of N2K. All those yellow lines in the diagram above, bigger here, represent SimNet data bearing cables (power too in many cases). I hadn’t fully realized that Simrad has N2K GPS, depth, and wind sensors as well as the rudder angle and compass that were mentioned with the new autopilots. Of course the AI50 Class B AIS would also plug and play nicely with this typical sail system, and give it a backup GPS, as long as it was powered up. And the SimNet cabling has a lot going for it, like a tiny plug that’s the same on both ends, and the ability to daisy chain, even the backbone in some cases like that RS86 VHF.
