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NMEA-2000: Building a System
|Author||Topic: NMEA-2000: Building a System|
posted 11-16-2006 01:15 AM ET (US)
Let's build a typical NMEA-2000 vessel instrumentation system. The first place to start is with the engine. Here our choices are limited because I believe that Bombardier is still the only engine manufacturer with a NMEA-2000 certified engine. Their 150-HP and higher engines support NMEA-2000 connections. We'll built up a typical small boat system and see what devices we need and how much they cost.
ENGINE HARNESS--To connect to the engine's Engine Management Module (EMM) data port we need a harness. This is simply a pre-made cable with the proper connectors and wiring. The wiring is done with TEW 105°C conductors and is sheathed in a high-temperature nylon mesh. On the engine end is an appropriate connector for the EMM and on the outboard end there is a 6-pin Deutsch connector. Also on the engine end is a connector to plug into the ignition harness so the ignition key switched battery voltage can be sensed. The presence of this voltage is used as a signal to "wake up" the NMEA-2000 network powering. In this way the network is only powered when the engine ignition key is ON. We run this over to the POWER HUB and plug into one of the network connectors marked "E1" (for Engine-1). (The E-1 and E-2 connectors are distinct because they're involved in the power monitoring process. The other connectors are marked N-1 and N2.) Bombardier seems very proud of this 10-foot cable; the MSRP is $72.67 (Ouch!)
ASIDE: I hate to jump off track already, but there does seem to be some debate about what the "standard" connector is supposed to be in an NMEA-2000 system. You'd think for all the time and money that has been spent by those involved that the details of the connector would have been worked out and cast in stone. However, there are already at least four different connectors used in NMEA-2000 systems. Bombardier has chosen a 6-pin Deutsch connector as their system connector, and in their wiring that is the normal connector being used.
POWER HUB--The Engine Harness runs from the engine to a power hub which is typically located in the stern. The hub consists of six connectors, as follows:
--(4) NETWORK connectors (6-pin Deutsch) for connection of other devices on the network;
--(1) POWER connector (3-pin Deutsch) for connecting to a 12-volt battery;
--(1) TERMINATOR connector (2-pin Deutsch) for connecting the network terminating resistors. We'll plug in one terminator ($4.81) to terminate this end of the network.
The HUB also has a red LED indicator which is illuminated whenever the network is powered. This assembly is mounted on a tray with flanges for fastening to a bulkhead. The POWER HUB should be mounted above the waterline and somewhere not likely to be exposed to spray or water accumulation. The MSRP is $99.50.
In a typical installation we will plug our EMM HARNESS from the engine into this POWER HUB and one TERMINATOR. We will also connect the POWER SUPPLY HARNESS to this hub.
POWER SUPPLY HARNESS--This is a cable and connector harness. There are individual leads and terminals for connection to a 12-volt DC battery. This will supply power to other devices connected on the network. One end connects to the battery, the other end connects to the POWER HUB. This is reasonably priced at MSRP $22.67 for a 5-foot version.
The back of the boat now has the engine, a terminator, and the battery connected to the POWER HUB. We have three open NETWORK connectors. Typically these can be used to connect other devices to the network. What other devices? Some possible choices are:
--another engine in twin engine installations;
We have to reserve one of those NETWORK connectors for a cable to run the network forward to the helm.
DATA HARNESS--this is just a two-pair cable that carries the NMEA-2000 network wiring and is terminated with the appropriate 6-pin Deutsch connectors (i.e., Male or Female) to connect to the POWER HUB or CONSOLIDATOR. The MSRP of this piece of wire is $42.06 for a 15-foot cable. Longer cables cost about $2/foot more. We plug one end into the POWER HUB in the stern, and run the cable forward to the helm console.
CONSOLIDATOR--this is a device similar to the POWER HUB except it lacks the power connector. You connect devices to the NETWORK connectors and add a TERMINATOR. The MSRP is $79.70.
OK, now we have the NMEA-2000 network run to the console and ready to connect some devices. What to connect? Let's add a tachometer and speedometer.
INSTRUMENTS--We select the I-Command Classic 3-inch Speedometer, 3-inch tachometer, and harness kit. This gives us the gauges and the harness to connect them. These combination analogue dial pointer and LCD screen readout gauges are expensive. MSRP is $575.99. We plug them into the CONSOLIDATOR and add another TERMINATOR ($4.81)
What have we built so far? A NMEA Instrumentation network with expansion capacity in both stern and at console. We can add two more devices in the stern and three more at the console. We have our engine connected to the network and also two displays. Between the two displays we get dedicated dial pointer displays for engine crankcase speed (RPM) and boat speed (MPH), and two LCD digital displays which can be configured to display about 20 more engine data readings.
Where will the speed data come from? Good question! We will need to connect a device to the network to supply speed data. This can be either a paddlewheel type sensor or a GPS receiver that has a NMEA-2000 interface. Those devices will plug into one of the open NETWORK connections available.
In our example, let's assume we also have a fancy new GPS and Chart Plotter on the boat, so we'll just run a cable over from it and plug it into a NETWORK port on the CONSOLIDATOR at the console.
How much have we spent so far? Let's add it up:
EMM HARNESS = $72.67
(I did not charge for the terminators as I expect they are included with some of the devices such as the POWER HUB or CONSOLIDATOR.)
NMEA-2000 is not exactly cheap, however we have now installed the infrastructure for the network. New additions to the network will now be simple and (we hope) easy. Also, I would anticipate you could probably get some discount from MRSP. Let's take a ten-percent mark down, and estimate our cost at $803.36.
posted 11-16-2006 09:04 AM ET (US)
The tachometer instrument is the prime element in any I-Command system. The speedometer is the only matching 3-inch instrument available. Exactly what can be displayed on the Tachometer/Speedometer gauges? Of course each gauge has a dial pointer for display of its main function. There is also an LCD display that can be switched to several different displays. Here is the list:
TACHOMETER LCD DISPLAY
Also, with the addition of extra sensors, the tachometer instrument can display
--engine water pressure
SPEEDOMETER LCD DISPLAY
Also, with the addition of extra sensors, the speedometer instrument can display
posted 11-16-2006 09:26 AM ET (US)
Let's investigate some of the extra sensors need. The one function I'd consider most important to add is WATER PRESSURE. This requires adding a transducer to the engine to monitor water pressure and convert it into a digital signal. This sensor does not connect to the NMEA-2000 network, but instead connects directly to the EMM of the engine. The EMM puts the data onto the NMEA-2000 network:
WATER PRESSURE TRANSDUCER KIT--MSRP $177.95
While we're at it, lets add a dedicated 2-inch gauge to monitor engine water pressure. This will give us a dedicated display for it, instead of just having it available on the tachometer LCD readout:
WATER PRESSURE 2-INCH INSTRUMENT KIT. This also includes a gauge harness to connect to the tachometer/speedometer harness. THis daisy-chains off the other instruments, and it does not use up a port on our CONSOLIDATOR. We still have two open ports there for more devices to connect--MSRP $89.90
TOTAL EXTRA $267.85 (Ouch)
Going digital on the water pressure is a bit expensive. An old fashioned water pressure gauge with a hose connection from the engine to the helm would be under $100 for the gauge, the hose, and the fitting.
I am surprised that the EMM doesn't already monitor the engine water pressure. In old fashioned engines, the engine controller didn't monitor the water pressure either. Typically just the water temperature was sensed and usually by just a thermostatic switch or several thermostatic switches with different temperature sensitivity. Thus in a conventional system, the engine would not be self-aware of the water pressure.
A corollary question: if you add the digital water pressure sensor, does the EMM use that data in its monitor routine? Will it alert you with an alarm if there is an out-of-tolerance value detected? I'll see if I can find out.
posted 11-16-2006 01:41 PM ET (US)
I believe that you can build an NMEA system for less, by using a full "digital" setup vs. analog.
By using the iCommand digital gauges (or the identical Lowrance gauges), you alleviate the need for several of the hubs (consolidator hub, power hub), and each Gauge is infinitely more flexible (you can display almost anything on a 3" digital iCommand gauge, including a either digital or analog style quad display), as well as literally costing less. For example, with the digital system, you don't need a separate "water pressure" gauge, as you can display it in either analog or digital "mode" on the digital gauge.
The real beauty of the digital package is the simplicity of installation. Here's what you need for a typical single engine setup with water pressure and fuel sensor kits, and the associated Evinrude part numbers:
763517 EMM Cable - 12"
You will also need the appropriate Engine Harness Kit, which will vary depending upon your engine setup. For my 150HP ETEC it was:
763544 Harness Kit, 20FT
To connect, you connect the EMM cable to the engine, install a "T" connector (included in kit) inside the cowling, which runs to the Water Pressure sender on one side, the the 15' Extension cable (or longer as need be) which runs to the next network device. In my setup, all my other network devices were in the console (including the fuel sensor which comes with a cable long enough for almost any Classic Whaler). The connnections are simple plug and play. Plug in the "terminator" at the end of the network and you are done!
I hope to take some pictures soon, along with a reference article (as soon as my 9 month stops crying).
posted 11-18-2006 09:56 AM ET (US)
Matt (mfrymier)--Thanks for the information on your LCD screen style NMEA-2000 instrumentation. I look forward to seeing and hearing more about it. Please take plenty of pictures and notes.
posted 11-17-2006 12:02 AM ET (US)
I want to continue to build my engine instrumentation using NMEA-2000 components from Bombardier. Let's add more 2-inch dedicated gauges so we can have individual gauges for BATTERY VOLTAGE and TRIM ANGLE. This is easy; we just buy the individual gauge kits. They include a harness to daisy-chain these gauges onto the instrument leg of the network. Here are the prices:
BATTERY VOLTAGE 2-INCH INSTRUMENT KIT: MSRP $89.90
Now my console instrument panel has five gauges: the multi-function speedometer and tachometer gauges, and three dedicated gauges for volts, water pressure, and trim. The cost is now up to:
TOTAL = $1,340.27
Figuring a 10-percent discount, this brings the instrumentation project up to about $1,206.24
posted 11-17-2006 12:28 AM ET (US)
It would be very nice to be able to monitor some tank levels, particularly the external engine oil reservoir tank. For this function we'll need to add a sensor. The readout is available as part of the Tachometer display.
OIL TANK SENDING UNIT KIT: This gets a bit complicated. There are different sensors for the 1.8-gallon tank and for the 3-gallon tank. Pick the one you need. Also, there are different sensors corresponding to the number of engines in the system, one, two or three. In my case I'll pick the 1.8-gallon tank size and the single engine system. This is P/N 763578, and it includes sending unit P/N 763407 for the 6.5-inch height tank. Confused? Yes, it is a bit complex. Check with the dealer before ordering.
This will be located at the stern and plug into one of the open network connections on the POWER HUB. Perhaps a picture will help. Here is what it looks like:
The MSRP is $139.89
posted 11-17-2006 12:50 AM ET (US)
I don't think you need separate guages for battery voltage,
water pressure, and trim.
For battery voltage you need a small readout somewhere of the
For water pressure, ditto, except that it really only cares
The trim gauge should appear when you change the trim, and
One of the fundamental rules in automation is that if your
posted 11-17-2006 11:45 PM ET (US)
With NMEA-2000 you can build all kinds of networks. The one I am describing here is more of a "classic" instrument panel with gauges that look much like traditional gauges.
Bombardier and Lowrance have some very nice instrumentation available with small LCD screens that can display digital values or more conventional dial faces with pointers. Using gauges of that style you can build a different sort of instrument panel than the one I am describing here.
One interesting thing to note about Lowrance and Bombardier gauges is that you can inter-mix them on a network. This is the beauty of NMEA-2000--you can combine all sorts of different brands and devices, as long as they are all NMEA-2000. At a trade show a NMEA-2000 network was assembled with over 40 devices from 17 different manufacturers. ( http://www.connectfest.org/ ).
You can build a network with Evinrude engines and Lowrance gauges. They'll monitor the engine speed and other parameters. One difference between them, however, is the ability of the Evinrude gauges to display more data about engine diagnostic codes. The Lowrance gauges will alert you to check the engine diagnostic codes, while the Evinrude gauges will give you the particular diagnostic code that has been set.
The "digital" gauges, that is the gauges with LCD screens as opposed to the more traditional analogue pointer gauges, have some of the features that the traditional style gauges to not. For example, the LCD displays have POP-UP functions. You can select particular data to be monitored, and, if the data changes, the instrument will automatically switch the display to show the changed value. Two possible choices for this POP-UP function include:
--ENGINE TRIM ANGLE
You can also select the tolerance for the amount of changed needed to cause a POP-UP. For example, in the engine trim, you can set the POP-UP to occur if the ENGINE TRIM ANGLE changes by more than 3-percent. You can also select a higher tolerance before triggering a POP-UP.
The ENGINE RPM can be set in a similar manner. You can select a tolerance of, say, 200-RPM. As soon as the engine speed changes more than that, the gauge display will switch or POP-UP to show engine speed.
To get back to the network I am describing, I located the price of the OIL TANK SENDING UNIT KIT. The MSRP is $139.89. I think that is a good value. The kit includes a very nice steel float sensor, a converter that adapts the sensor to NMEA-2000 (which appears to be a Lowrance EP-15 unit) and an adapter plug to convert the connector from the Lowrance-style plug to the Evinrude Deutsch (6-pin) connector.
You can also mix the traditional style gauges with the LCD gauges. A nice combination might be to use the traditional style analogue-pointer gauges for the tachometer and speedometer functions, then add a third large-size gauge with full LCD display. You can program this third gauge to show all sorts of data. In fact, the LCD display style gauges have a very extensive set of configuation menus. You can customize them to do exactly what you want. For computer nerds, these LCD gauges are a great way to take your electronic gadgetry with you when you go boating!
posted 11-18-2006 03:17 AM ET (US)
"You can also mix the traditional style gauges with the LCD gauges." --Jimh
Jim--if you're speaking about combining the I-Command Classic with the new I-Command Digital you cannot. You can have I-Command Digital analog-style readout combined with the I-Command Digital digital readout.
posted 11-18-2006 09:50 AM ET (US)
I just saw a NMEA-2000 network which contained a mix of the I-Command CLASSIC analogue pointer gauges and LCD screen digital gauges, and they appeared to be coexisting without problems. Perhaps the LCD gauges were LOWRANCE brand--that may affect this situation. I will double check on the configuration and verify which brand of LCD gauge was used.
A feature of NMEA-2000 networks is their ability to contain many different devices.
posted 11-18-2006 10:00 AM ET (US)
For more information on NMEA-2000 instrumentation, refer to this article which indexes much of the prior discussion in SMALL BOAT ELECTRICAL on these topics:
Index to NMEA-2000 and I-Command Information
posted 11-18-2006 02:29 PM ET (US)
Using NMEA-2000 as a vessel network is not really a case of automation. But Chuck's comments are interesting, and I'll respond.
Building a NMEA-2000 engine instrumentation system which just mimics a traditional installation is perhaps not the best use of the vessel network approach, nor, as we have seen, is it the cheapest, either. The instrumentation system I described above has five separate gauges. Several serve a single dedicated function, while two of them have multiple uses. And the primary unit, the tachometer instrument, offers many optional data displays and functions. In order to get the same results with conventional, dedicated displays and non-networked connections, you would need many more gauges and much more wiring.
Even if the system I described offered only five functions for display, there would be significant gain in a reduction of the wiring complexity. And all of these gauges just plug into the network and configure themselves. This simplicity may appeal to some installers.
The cost looks rather high, but there are some considerations which may offset it. Remember that once you have installed a NMEA-2000 network in your vessel, you can add additional devices at relatively low cost and without much difficulty.
posted 11-20-2006 11:17 PM ET (US)
I had a chance to see some of the cable assemblies supplied by Bombardier for their NMEA-2000 system. These cables are quite heavy-duty. The conductor size is substantial, probably larger than needed by the electrical requirements, and very like made larger to have better durability in a boat installation.
I also noticed that the cable assemblies were marked "Made in Canada." Apparently they are being fabricated at one of Bombardier's facilities in Canada, not in Wisconsin.
posted 11-21-2006 12:34 PM ET (US)
jimh, nice article, and per my experience quite accurate. Here are a few thoughts on this topic from someone who has built and used one of these systems. In fact, I used a schematic diagram published here about a year ago as the basis of the I-Command system I put together http://continuouswave.com/whaler/reference/NMEA2000/ iCommandSingle729x337.png
Water Pressure Guage/Sending Unit - Initially, I choked at the price of this, but having run the boat with it for a while, I'm really glad I made the investment. When I'm running the boat, It's virtually impossible for me to see the confidence stream, not to mention the danger of looking backward while piloting the boat. I often fish in areas with a lot of kelp, and it's easy to plug the water intake and overheat a motor. A quick glance down at the pressure gauge lets me know the engine is getting plenty of cooling water, and that my water pump is in good operating condition. Installation was a snap, and the EMM is ready to send the signal automatically. Although the LCD display on the Tach can show the pressure reading, I find the round pointer gauge much easier to see while running at speed. I never liked the idea of a long tube of water running into my console and terminating right next to all the exposed terminals of my electrical panels, so the old style gauge was never an option for me.
Trim Gauge - I went with an analog gauge for this function because I hate looking over my shoulder while driving the boat. By using the gauge, I can instantly know the position of the motor without looking, and easily adjust to the "known" sweet spots for the given conditions. This is the first time I've ever had a functioning trim gauge on a boat, and it's a nice luxury. Yeah, I can trim the boat the old fashioned way, but this makes it much nicer. Resolution of the gauge is excellent.
Oil Tank Sending Unit - I considered one of these, but decided it was not terribly useful. First of all, these motors really don't burn much oil at all, certainly nothing like a typical carburated 2-stroke. Because of this, you'd have to run through an awful lot of gas before the tank even gets low. The stock BRP oil tanks are already outfited with a low oil level warning sensor, which alarms well before the oil pump loses suction. I suspect these sending units are designed for applications where the tank is mounted remotely in some hold or bilge area where it can not be easily inspected.
Battery Voltage - I use the LCD display in the tach to get this reading for my start battery, and the display on my sonar to get this reading from my house battery.
GPS connectivity - I have to wait for my old non-NMEA 2000 instruments to fail before I can justify the upgrade to something that will tie into my network, but I plan to do it eventually.
Harness Robustness - jimh is right on the money here, these are heavy duty wiring harnesses, that are nicely fabricated. The connectors are double O-ring gasketed, and pop together with an audible snap.
Plug and Play - I put my system together one time, and it all worked the first time. No trouble shooting, no fussing with tiny ring terminals and nuts under the console, and a rather neat bundle of wires when it's all done. How much would you pay for that?
Aesthetics - The tan faced gauges with chrome bezels look sharp on a classic Whaler instrument panel. The tan is a great match to the desert tan gelcoat. Also, the gauges are illuminated with red backlighting, which is easy on the eyes and looks really sharp.
Here's a photo of my installation:
posted 11-21-2006 07:54 PM ET (US)
That may not be necessary, there are gateway devices out that let you interface your NMEA 0183 devices with the newer NMEA 2000
I have not tried it yet,but hope to include it when I get the engine and do the rigging this winter.
posted 11-23-2006 10:30 PM ET (US)
The LOWRANCE LGC-2000 GPS module contains a 12-parallel channel GPS receiver which connects to a NMEA-2000 network. It retails for about $180. You could add this to your system. It probably costs less than the convertor device mentioned above.
posted 11-24-2006 01:26 AM ET (US)
jimh, that actually sounds quite reasonable, considering what I was willing to pay for the water pressure sending unit and gauge. That said, all I'd really get from having that device is the ability to automatically calculate my fuel economy. Some time down the road, I'd like to have my radar and GPS chartplotter on the same large color display. That would be pretty neat, so I'm saving my pennies for now.
posted 11-24-2006 09:41 AM ET (US)
Andy--Those Evinrude I-Command Classic gauges with the tan dial faces look absolutely spectacular on the Desert Tan console of your classic Boston Whaler boat. What a great choice!
You can see the underlying nature of the gauge pointers in that picture. They are really little servos motors running the dial pointers in response to digital data from the motor via the NMEA-2000 vessel network. When they are off the dial pointers seem to end up in random positions. When the gauges are powered on, the dial pointers swing up and down across the gauge face as the servo system initializes. They let you know that they're not your old-fashioned D’Arsonval or Weston meter movement type indicator.
posted 11-24-2006 02:15 PM ET (US)
jimh--That's exactly right. When starting the boat, I turn the key to the on position for a moment, and the alarm test tones sound while the gauges "zero" themselves. It takes a second or less. Then it's a quick click to the right and the E-TEC is humming, although barely audible.
I am very pleased with the aesthetics of these gauges, and find the color match to be quite good with the Whaler desert tan console.
Although these gauges have an analog pointing device, there actuation is really digital. This begs the question: are these analog or digital gauges?
posted 11-25-2006 02:04 PM ET (US)
Re mixing of I-Command Classic and I-Command Digital gauges in the same network. There is a note that you cannot mix the two types shown in
On page five of that document there is a footnote:
"IMPORTANT--Classic and Digital systems cannot be combined"
This may be due to the way the instruments identify themselves on the network.
posted 11-26-2006 07:36 PM ET (US)
[Moved article seeking to re-new comparison between NMEA-200 and SmartCraft systems to a prior discussion which was precisely on that topic.]
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