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ContinuousWave: Small Boat Electrical
Displaying Jack Plate Height on NMEA-2000 Gauges
|Author||Topic: Displaying Jack Plate Height on NMEA-2000 Gauges|
posted 04-21-2010 12:02 PM ET (US)
I have a Bob's hydraulic jackplate. My Bob's LED gauge just went bad, and of course, is out of warranty. Does anyone know if an I-Command gauge can be set up to read the sensor? Maybe using my unused Trim Tab setting or some other way? I'd rather buy a small I-command to replace the Bob's gauge than a new discrete jackplate gauge.
posted 04-21-2010 03:36 PM ET (US)
I-Command Gauges are NMEA-2000 network devices. What NMEA-2000 parameter group number (PGN) corresponds to jack plate height? You'd need a sensor that generated that PGN. Then check with Evinrude to see if the I-Command gauge can display that PGN.
posted 04-21-2010 05:45 PM ET (US)
Thanks Jimh, yeah, I installed my gauges and NMEA network myself, so I under the technology. I guess what I was asking if there are any sensor that will replace, or anyway to hack the sensor I already ahve to be read by I- command/NMEA... any info you can provide would be appreciated.
posted 04-21-2010 09:17 PM ET (US)
OK, let me try again: what NMEA-2000 PGN is used for jack plate height?
posted 04-22-2010 09:29 AM ET (US)
I also have a little bit of understanding of the technology of NMEA-2000, so in assessing this problem the following immediately occurs to me:
On the notion that you could make an NMEA-2000 sensor to work with the jack plate, the first thing that occurs to me is how far out of the question this really is. Development of your own NEMA-2000 device is clearly much too large a project. An entirely new device would have to be invented, and the PGN registered with NMEA, and so on. All of that would require an enormous amount of work and expense, probably fifty times more than the cost of buying another gauge from the jack plate maker, not to mention a huge amount of electrical engineering and computer code development, This approach is pointless.
Next, we consider the possibility of adapting some existing NMEA-2000 sensor to connect to the jack plate sensor. This avoids having to invent our own new NMEA-2000 device. At the moment we know nothing at all about the electrical nature of the sensor the manufacturer has provided on the jack plate. It is a mystery. However, we assume somehow we could interface the existing jack plate sensor to be electrically compatible with some existing NMEA-2000 sensor. On this assumption we can proceed further.
We have to figure out what existing NMEA-2000 sensor might be useful. A reasonable choice might be trim tab position sensor. We know that the trim tab sensor in an E-TEC is sending a voltage to the EMM that varies over a certain range. Perhaps we could modify the jack plate sensor to work with mimic this voltage. Since we know nothing about the jack plate, no advice can be offered on adapting it to somehow become compatible with the variable voltage of a certain range needed to feed the EMM. Again, we assume that some type of electrical adaptation could be made between the existing sensor on the jack plate and the required electrical input for the trim sensor. However, I must caution here that the trim sensor is wired into the electrical harness of the E-TEC. The existing trim sensor would have to be disconnected, and the jack plate sensor then would be connected to the trim circuit wiring in the engine.
Now we could display the jack plate level on an NMEA-2000 device, however the data would be sent with the PGN for a the trim position. The device might be configurable to show this data. Perhaps if the device is very configurable you could change the legend of the display from "TRIM" to "JACK PLATE POSITION." This would depend on the capabilities of the display device to be reconfigured. In the I-Command gauges I do not recall any device which could be reconfigured like that. I don't think you can change the LEGEND on the display.
I see a few problems with this approach. First, you have to make some changes to the wiring in the engine which connects directly to the EMM. The EMM is a very expensive component, so be sure you know that you're doing before hooking up anything new to the EMM. Second, you'd lose the trim position indicator. For me the trim position is more important than the jack plate position. I suspect the engine trim is adjusted more often than jack plate position, so losing the engine trim to get the jack plate position does not seem like a good trade. Third, the wiring to the jack plate would of course be external to the engine, and you'd have to route this from the jack plate back to the EMM.
posted 04-22-2010 10:12 AM ET (US)
Sorry, I did not see your question about the PGN.It sounds like too big a project for me to try myself, but one would think that with all the wonderful things that an I-Command gauge can do, and something as common as a jackplate, they would have a sensor available thst would work on the gauges.
Guess I'll have to spend the $160 buck on a Bob's replacement.
Thanks Jimh for all your info....
posted 04-23-2010 12:29 AM ET (US)
You need to findout how Bob's hydraulic jackplate solid-state transducer works.
If it's simple resitance then a tank or rudder analog to Nmea2000 sender could be used.
Your I-Command gauge would read it as a tank or a rudder and you would need to understand the calibration of the display not disimilar to trim gauge.
The tank/rudder sender is likely to cost the same as Bob's replacement and I assume you would have a redundent hole in your console if you remove Bob's LED guage.
It's probably not worth the effort
posted 04-23-2010 12:43 AM ET (US)
Most of the NMEA-2000 tank level network interfaces are compatible with existing tank senders which have a variable resistor that sinks current. The resistor or rheostat varies from around 35-ohms to around 240-ohms, which seems to be more or less a universal tank level sender standard.
If you could adapt one of these tank level senders to the jack plate, you could connect an NMEA-2000 tank level sender to the jack plate, then connect the NMEA sender to the network.
The NMEA sender would send the PGN for tank level. Usually there is some sort of set-up needed to configure the network so it can tell what sender is associated with what tank. Perhaps this configuration process would allow you to give the "tank" a new name, something like "JK PLATE" or similar.
A tank level NMEA-2000 interface costs about $75. They usually have their own drop cable as an integral part, and usually come with a network T. So for $75 you have a possible solution. The only engineering is to made an adaptation between the 35 to 240 ohm resistance needed for the NMEA sensor and whatever you have currently on the jack plate.
One problem I see with the jack plate level sensor is the very close proximity to the water and the very likely chance of the sensor getting immersed in water. You would have to do some engineering and design to get a waterproof sensor working. You would also have to make some sort of mechanical interface, too.
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