By Ben Ellison
Plug Prayers Answered
|NMEA 2000 really works, and it’s going to make boating better.|
Oh, it’s a strange-looking rig—and, yes, I do draw some looks around the harbor—but I don’t care; the NMEA 2000 test system above just tickles me pink! As odd as I may look with it c-clamped to my rail, I figure I’m looking at the bright future of nav stations aboard everything from my 14-footer Gizmo up into megayacht territory.
And I’m not talking about the vivid displays on the Raymarine E120 and Simrad CX34 plotters, though these machines deserve their due in future columns. I’m raving about how I just plugged them into the network of sensors in the background, and—no fiddling with setup menus, let alone wire strippers—everything just played nicely together. Simplicity, redundancy, multimanufacturer flexibility—my first hands-on experience with NMEA 2000 was, as we say up here in Maine, a corker!
Let me be more specific. First I unpacked a box of the standard Micro-size cables, tee fittings, sensors, and that grayscale display, all from Maretron. It came with a useful guide to various 2000 network configurations, but this relatively simple setup was pleasantly similar to working with Tinkertoys. You have a trunk line—in this case (see page 42) tee-to-tee short, but it could snake up to 325 feet from flying bridge to forward utility locker to engine room. Wherever you want a network device, you plan a tee drop. The wires are made up in various lengths with keyed male and female ends—virtually foolproof. (Raw-wire and straightforward field-attachable plugs are also available.)
Note the yellow cable; it’s a 12-volt power tap that feeds 4 amps to each side of the trunk (alternatively you can get a heavier Mini-size cable capable of 8 amps per side and longer runs). Thus the test system’s GPS, display, compass, depth/speed/water temperature transducer, and PC gateway are all powered off the network cable (with, it turns out, plenty of amperage to spare). So all I had to do was screw together the cables and wire the one power feed; everything came on, and the display recognized all sensors and was ready to show me screens of info.
Then, as noted, the plotters both found and used most of the Maretron data. (Neither recognized the available roll and pitch angles, but it’s there should a future version of either’s software want it.) The Simrad had its own GPS and naturally chose that over Maretron’s, but it recognized both and offered me a choice via a thorough interface menu. The Raymarine selected the Maretron, which I—simulating a failure—proceeded to unplug. The E120 beeped me that it had lost position and then moments later picked up the Simrad output! Either way, such easy redundancy would have previously meant limiting oneself to one brand, digging deep into incomprehensible submenus, or devising a complex, possibly unreliable, data switch.
Now is a good time to recall PMY editor-in-chief Richard Thiel’s struggle with noncompatible plugs, confusing nomenclature, and more, just to make one “simple” NMEA 0183 data connection (“Plug and Pray,” June 2005). And, if installing electronics isn’t your thing, remember that you pay for complexity and unreliability sooner or later. Good installers—often using gizmos like multiplexers—have made 0183 work, but its abilities are way short of today’s needs, and it never even had the plug standard, speed, error protection, prioritized messaging, and rigid certification process of NMEA 2000.
By contrast, the test network combined data from multiple sources seamlessly. For instance, both plotters were able to show me the set and drift of the current I was motoring in, a sophisticated calculation that I’ve never tested before because temporarily rigging all the needed sensors was too much hassle, even for one machine (let alone two plotters of different brands, plus a PC, plus the 40 other devices that this network could support). And note that full AIS, a terrific safety technology but an installation bear, wants the same data (see Q&A).
This article originally appeared in the August 2005 issue of Power & Motoryacht magazine.