Digital Gauges

[Photolomy]

I finally got around to installing an analog-to-digital solution for my engine gauges. I am not doing away with the analog versions, and I have been replacing the broken ones with Stewart Warner but it is a pain because you have to make sure you get dual station senders, etc. Anyways, the digital solution doesn't care about all that and it not only handles all of the gauges, but also the bilge pumps and my alarms (at the helm). I still have a couple inputs left that I might use for fuel levels, if I ever get fuel level senders for my tanks. I might instead use it for my rudder. I would love to know where it is pointing when I start out.

I was looking at several solutions, but a couple (Actisense and Alba-Combi) were foreign, so they were kind of at the bottom of the list. Two rose to the top of the list, Noland and Chetco, because of the number of inputs supported. And of course, there is Maretron, but their solutions require additional pieces and start running up the cost considerably. I should note that I really wanted to do my own Arduino solution but the NMEA-2000 piece would have taken too much time to research. The analog to digital part is pretty straightforward, but there just wasn't enough open source stuff available for the NMEA-2000 part, and it would have cost me considerably more in time than to just buy something already made.

So in the end it was between Noland and Chetco. I think Chetco is more advanced but it turns out in a bizarre coincidence, Noland's office is a couple blocks from my boat. I have been looking at these things for months and only recently noticed that the Noland address was in the same city, and when I googled it, it was within walking distance. Also, I already have a PC on board that I can access remotely and control the lights etc. And the Noland box interfaces with that PC easily.

I was originally going to get a pair of RS-11's, which is their more popular model, but changed to the MD33 model for the following reasons...

1. It has RPM and 5 inputs for each engine, while each RS-11 had RPM and 6 inputs, but the MD33 also has 5 on/off sensors for each engine as well, which covers all of my bilge pumps and engine alarms, plus a couple more for whatever.

2. The MD-33 has a serial interface built in that not only sends the sensor data it collects, plus also most of the common NMEA-2000 traffic and NMEA-0183 traffic. This saves me from having to add an additional NMEA-2000 interface.

The MD33 also comes with a PC app to display the gauges, but I am actually going to integrate the data into my existing applications, but it is handy to use the supplied app for testing and calibration.

I'll post pictures over the next couple of days of the installation. The nice thing about the MD33 (and I assume this is also true for the Chetco) is that it can operate with or without the analog gauges. This means that you can wire it directly into your helm where everything is close by. I mounted mine on the back of the front panel, right below the Newmar 12V converters. Creating a wire harness wasn't too bad, but it was a bit of challenge getting 26 wires into the small opening on the MD-33. After that, the only real challenge was working in the confines of the helm amongst the other cables. Nonetheless, if you are prepared, it can be done in a weekend.

[JD5652]

Sounds like a great project.... and I need to do the same.... very interested in how yours came out!

[Photolomy]

Here is a picture of the device itself ...

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Across the top are the analog and digital inputs for each side (PORT and STBD). The A5 analog input on each side has a range of 0 to 40 volts, which makes it perfect for the volt meter. The remaining analog inputs have a range of 0 to 30 volts which works for the rest of the gauges since they operate on 12 volts. On the bottom are the RPM inputs and the NMEA-0183 in and out if you have some older stuff. On the left is the NMEA-2000 connector and on the right is the USB (top) and access for all the wires to the gauges (bottom).

To build a wiring harness to attach the MD33 to the gauges etc, I chose some 20 gauge 8-wire color coded cable from West Marine. I didn't need a lot, or I would have sourced it somewhere else.

https://www.westmarine.com/buy/ancor--20-8-round-signal-cable-by-the-foot--541748?recordNum=7

This allowed me to have 3 bundles, one for each engine, and one for the alarms/bilge pumps.

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And finally, here it is with all of those wires inserted through that too-small hole and connected. I used the same colors for each side (PORT and STBD) to make it easier when connecting to the gauges. You definitely want to do all of this on a table first, before installing in the console. And make sure you mark which cable is which. You can also see the red/black power cables. There are a total of 26 wires running into the box. 10 analog, 10 on/off, 4 RPM and 2 power.

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[Photolomy]

Here are a couple pictures of the helm prior to the install. This first picture is of the lower section...

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The black boxes are the Newmar 32v to 12v converters. The two smaller (3 amp) converters are for the gauges, port and starboard. There are inline fuses above each converter that are a bear to open. If the gauges on a whole side (except the voltage gauge) are not working, then go to the fuse first. Keep in mind that the fly bridge is separate and has its own Newmar converters, just like the lower station. Just something to keep in mind when troubleshooting gauges.

Above the Newmars is a fuse block for the gauges and parallel switch. To the right of that is the alarm buzzer and to the right of that is the back side of the console alarm unit. I cleaned out a lot of wires from all the older electronics (Loran, Depth Sounder, etc.).

The MD33 will mount below the Newmars and it will be powered by the 12v generator battery which also powers my radios and chart plotters. The MD33 only draws 0.1 amp, so you could easily power it from one of the Newmars, but the Newmars are only live when the ignition key is on, which is how they last 40 years. But I want the MD33 on all of the time because it will also monitor bilge pump activity and the high water alarm. Thus is why I connected it to the generator battery. Before I did this, I used a multimeter to make sure that the ground of the generator battery was common to the gauge grounds (main batteries) and that appears to be the case. The MD33 has only one ground and in order to measure the gauges that ground has to be in common with them. In any event, it was.

This is the picture of the upper part showing the gauges...

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The MD33 will handle all of these. Keep in mind that only the A5 input will handle 40 volts, so those must be connected to the voltage gauges. A1 through A4 are connected to the other gauges. I only needed A1 through A3 for Temp, Oil and Drive Pressure. There are two additional connections for the tachometers. I actually only needed one wire for each tachometer. The inputs connect to where the senders connect to the gauges. You can see where that is because that will be the terminal with only one wire connected to the gauge. The other terminals have multiple wires connected because the ignition and ground wires are daisy chained from gauges to gauge. Make sure the key is off when working back here because the space is cramped and you will be blowing fuses left and right, or blowing gauges. All of the gauges operate on 12v, except the voltage gauge which is 32v.

Four on/off inputs connect to the bilge pump indicators at the right. For those I use resistors to bring the voltage down. Likewise, I will use four on/off inputs with the alarms, though I am still working out the method.

And of course, the NMEA-2000 will connect to the Garmin.

[davidwigler]

So it works? I have the MD33 I bought years ago and never could get it working. How much would you want for a working vacation in Knoxville? 😃

[Photolomy]

Here is a shot after the install. I still have some cable management to perform.

IMG_1133.jpg

I have been calibrating and so far that is going ok, but with a variety of old senders, I can see how this step can be troublesome. The tachs are pretty easy, as is the voltage gauges. I tested the unit with a spare temp sender and water heated to various temps and was able to dial it in pretty well. In fact, it was tracking a cooking thermometer within a degree or two. For the pressure gauges I am taking an educated guess from my working gauges. I'll have to install mechanical gauges to get more accurate readings to calibrate to. I'll post some screen shots of the app and the Garmin while the engine is running as soon as I dial it in more. I also have a bad drive pressure sender, or a loose wire.

Btw, what are common pressures for the oil and drive at idle? I am getting around 40 and 150 psi.

[davidwigler]

Oil pressure starts at 40 plus cold and warms to around 20 psi at idle.

My gear oil pressure reads around 100 to 120 psi, lower than most.

Mechanical gauges in the ER.

[Photolomy]

So it works? I have the MD33 I bought years ago and never could get it working. How much would you want for a working vacation in Knoxville? 

Yeah, it is working. The box and the firmware seem very solid. It has been on continuously for a couple of days, even while I have been connecting and reconnecting gauges. The app crashed a few times though, but I figured out what it doesn't like, such as cancelling a config window or trying to connect without the USB plug in. What has taken some time though is realizing that while you can configure the app gauges to be what you want them to be, you are limited on the NMEA messages that can be associated with the inputs. For example, you can use engine temp, but it has to be with A2, while oil pressure can be used with any input. Thus, the app was setup and working but the Garmin gauges were either doing nothing, or showing gibberish compared to the app gauges. I finally figured that out and now the app and the Garmin are saying the same thing. Now I am looking at the condition of a couple of my senders, which is one of the purposes for getting this. Once you do set it up the voltages it reads are pretty accurate, within 1% at least, and I can watch a remote screen in the ER while I fiddle with a sender.

I hope maybe what I post here might help you along. How far did you get when you tried to hook it up? There are some pitfalls like what I mentioned above. If you start off just wiring gauges in any order (like I did) you might not get the expected results on your multifunction displays. I had to change how I wired them a couple times before I straightened it out. Fortunately, I did this on the port side first, so I knew what I was doing when I did the starboard side.

[Photolomy]

Some shots of the Garmin with everything hooked up. In some shots the engines are running, some not. I didn't run the engines very long, so they didn't warm up. I have a monitor attached to the Garmin on the side, showing the same screen. The Garmin has an extensive number of layouts.

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Comments thus far...

The unit seems very reliable from an up-time perspective. It is wired directly to the fuse box so it has been on all the time for the last couple days. I will add a switch so that I can turn it off when I need to, or to reset it if that ever happens. Likewise, the serial port drivers have been reliable thus far, and I am pretty sure that it will function fine connected to my ship server, logging and reporting (via email) any bilge or alarm activity.

Regarding the engine monitoring, it depends on the condition of your senders...

RPM good (I checked with a laser tachometer). There is some jitter at low RPMs but that goes away at higher RPMs. Similar to the analog gauges I suppose.

Water temp seems fine, the senders have a decent range.

Oil pressure, one is "ok" but the other has a narrow range which affects accuracy and jitter.

Drive pressure, again, one is "ok" but the other has a narrow range.

Regardless of the sender issues, I was able to calibrate to the narrow ranges and get readings, however, the narrower the range the less the accuracy and the more jitter in the readings. The Garmin does a good job of smoothing the data, while the app that comes with the unit does not smooth at all I think. I generally use the app for calibrating though and the application I write will smooth.

Next step is to replace some senders and add mechanical gauges in the ER as a reference.

[Photolomy]

What is a good (and easy to install) sender for the fuel tanks? Are the ultrasonic senders any good?