N2K Instrumentation - Part 2 of Electronics Upgrade

dtfeld

Water Contrails
GOLD Sponsor
Jun 5, 2016
5,519
Milton, GA
Boat Info
410 Sundancer
2001
12" Axiom and 9" Axiom+ MFD
Engines
Cat 3126 V-Drives
Now that I have the a128 installed and working pretty well, I am going to digitize all of my instruments. The impetus for this is that my Tach's are barely functional. They are split from about 50 RPM to over 300 RPM depending on the engine speed and are just tempermental.

Two new Aetna's are about $750, and I'm not a fan of the digital read out, doesn't fit with the other guages. After much research into the Noland Engineering RS11/RS33, the Albi-Combi, and Chetco Digital SeaGuage G2, I selected the Chetco Digital Sea Guage G2. All of these options are about $750 as well, but add the ability to digitize more than the tachs.

A lot of the information is based on the experience of Orlando "SKybolt" He's on here as well but here is his post over at THT

https://www.thehulltruth.com/marine-electronics-forum/881525-chetco-digital-sea-gauge-g2.html

In addition to upgrading the Tach's, this will allow me to add pressure and temp instruments to the transmissions, similar to Ttmott's upgrade.

http://clubsearay.com/index.php?threads/save-your-transmission-modifications.66004/

Another goal was to add remote monitoring of critical systems, most importantly the bilge pump alarms.

A couple of other things that could be monitored, but I'm not doing is the Generator can be monitored and Chetco has NEMA2k dual channel fuel flow meters that are about $500 each. Maybe in the future...

FF Sender.PNG
 
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I ordered a unit with 3 Pulse inputs, 12 analog inputs, 8 status indicator and 4 relays. I also upgraded to have on board Ethernet. Received the unit along with a couple schematics, 3 special cables for Ethernet connectivity, USB programming and the configuration software. This unit can be installed in parallel to the existing dash gauges, or directly to the sender units in the engine room. I'm paralleling the dash gauges.

So the first step is to wire the unit up. I used crimped ring terminals across the board. 12V DC was routed off my exiting Electronics dash switch.

The tachs have a sender and a ground lead for each tach. Port is Grey (+) and White/Grey (Gnd), Starboard is Purple (+) and White/Purple (Gnd). These are attached to their respective sender and ground on the back of the tachs.

The other gauges, P&S Oil Pressure, P&S Engine Temp, P&S Alternator Voltage and P&S Fuel Qty are all single wires attached with a ring terminal on each gauge's sender terminal.

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I had to purchase a SeaTalk NG to DeviceNet (NMEA2000) Adapter Cable, Female Raymarine Part# A06045 ($30 @ West Marine), a SeaTalk NG T connector ($10 used on Ebay) and a 1m Seatalk NG backbone cable. This was attached to my existing Seatalk to Seatalk NG converter added in a previous upgrade.

The ethernet cable (supplied by Checto) was run to my onboard router to allow viewing of data and on board configuration via the embedded web server.

The last connection was a programming cable (USB) to allow direct connection and programming.


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The Next Step was to make sure I had it wired correctly and data coming into the G2, and that was at least giving raw data. I then started to calibrate the tachs.

I used a hand held optical tach to measure my idle RPM's at 730. The tachs required a couple of minor changes on the Options page of the Prescale and Scale settings, and I was able to get the display within 10 RPM, displaying 720 very consistantly.

Updated Proceedure - I made some modifications after speaking to Chetco Digital. What this is exactly doing is "PFM". Not much detail on the inner workings. However, I'll detail what I've learned the se items mean.

On the vDash Preferences Page - Options Tab for the Pulse inputs (Pulse 0- Port tach). My settings are in Bold.

Input -> Disabled, Enabled 1X, 2X or 4X - This is you "sample period" I beleive the default sample rate is 1 second. If you choose 1x you count pulses for 1 x your sample rate or 1 second, 2x=2 seconds 4x=4 seconds. The longer you count pulses, the more accuracy, but the response time is much slower.

Mode - For tachometer, select Pulse X/1 where X= the pulse input (0-2) This option can also be used for fuel flow measurements on diesel fuel flow guages where fuel flow senders output pulses and calculate the diference between fuel input and return to determine fuel burn in a diesel engine.

Prescale - -> 0-255 (31)Adjust this number to match your tach output to your laser tach rading from the engine flywheel.

Scale -> -> 0-255 (15) Seems to determine the increments shown on the RPM scale. additionally, when modifying this value, you must also modify the S or P RPM value on the vDash Preferences Page - NEMA 2000 tab to be 4x this value (60) in my case. If I selected 10, this value would be 40.

Time -Not used in my application

Display Gain -> Not used in my application

Preferences.PNG


N2k.PNG


I then changed out the calibration files to match the low to high resistance type senders on the files page in vDash. This gave me generically linear data, but I still need to go back and calibrate all of these to my actual senders and respective data.

Files.PNG


Finally, I checked on my Raymarine data pages and I was getting data that was "in the ball park"!!

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Next Step I will need to update the calibration files to match my senders/data.
 

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Calibration

Tachometers - Using the setting listed in the modified procedure above, I measured the RPM values displayed on the MFD vs the actual reading I took using a handheld laser tach at the fly wheel. I'd like to see it a little tighter at higher RPM...I'll have to work on that.

tach measure.PNG


Engine Temperature - Calibrating the senders is a little more difficult due to little or no documentation. Thanks to Skybolt for walking me through the first one over the phone. Not sure I would have figured this out on my own. The basic approach once you get your G2 connected up is to use vDash to identify what the "raw" data is in vdash, then correlate that to an actual measured value. Has to be done in real time as once the temp starts moving, it goes pretty quick.

Raw Data can be seen on the various vDash Screens. I measure engine temp at the temp sender as at the coolant inlet to the HEX with a laser thermometer and recorded the data

Where to read vDash 'raw data"

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Port data

Port Temp.PNG


Starboard Data

Star Temp.PNG


The next step is to input the data into the calibration files, and let the software calculate a linear output from these value. In vDash Preferences, choose files, and select the Linear_LowToHigh_N2K.txt file, and open it.

Cal 1.PNG



Once open, you'll find your first vdash raw data point in the table, in this case 85, double click, and enter the actual measured temp (185) into the "New Value" field and click OK You will see that the Raw data point of 85 now has a "Measured" value of 185. Repeat for your other data points. 2 is a minimum but I used 4 the first time out. You can add a lot more for more accuracy.

Cal 2.PNG


After you have entered your data points, Select Interpolate (this linearizes the curve), give the file a unique name, and hit OK.

cal 3.PNG


After I performed this procedure for both engines, I had reasonable data being presented on my MFD. I think I can redo this and be a little more accurate, and add a few more data points.

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Next onto Oil Pressure and the transmissions.
 

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Now that I have the a128 installed and working pretty well, I an going to digitize all of my instruments. The impetus for this is that my Tach's are barely functional. They are split from about 50 RPM to over 300 RPM depending on the engine speed and are just tempermental.

Two new Aetna's are about $750, and I'm not a fan of the digital read out, doesn't fit with the other guages. After much research into the Noland Engineering RS11/RS33, the Albi-Combi, and Chetco Digital SeaGuage G2, I selected the Chetco Digital Sea Guage G2. All of these options are about $750 as well, but add the ability to digitize more than the tachs.

A lot of the information is based on the experience of Skybolt over at THT. I beleive he is on CSR as well. Here is the link.

https://www.thehulltruth.com/marine-electronics-forum/881525-chetco-digital-sea-gauge-g2.html

Did you consider doing something like this with the Aetna's?
IMG_2394.JPG
 
TNT8808, how did you do that?

My mechanic/technician helped, but basically when you remove the Teleflex gauge you'll notice there's basically a plastic "can" on the back. Cut the can in half, and remove the guts. The flat area where the needle is now just so happens to be the perfect size for the Aetna gauge and it drops right out still leaving angled edge around the perimeter. Put the Aetna in place with a little silicone to help hold it in, glue the can back together, and reinstall. If I were to do it all over again, I would have ordered the black bezels.

-Tom
 
Looks good, sounds easy enough, thank you TNT.

Anytime Woody. I ended up selling that boat, but with the sync on they were within 1-2 RPM of each other.

-Tom
 
Tom

Your Aetna's look great!

I did consider this option...but i had other additional goals. This does a lot more than the Aetna tachs for about the same $, so IMHO, a better bang for the buck or .8 boat bucks.


Long term, probably use displays instead of guages.

Goals

Digitize the tachs
Add transmission pressure/temp senders
Add remote monitoring of pumps/alarms
 
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Added tachometer and coolant calibration how to.
 
David - Curious
I can't seem to determine from what you have provided above if the Chetco converter calculates an algorithmic curve to the thermistors or linearizes as best as it can. I had to apply a best fit line over the voltage curve thermistors output to get the Noland product to work; I think I wrote that up.
Does it track temperature from cold to hot or is the cold inaccurate?
 
David - Curious
I can't seem to determine from what you have provided above if the Chetco converter calculates an algorithmic curve to the thermistors or linearizes as best as it can. I had to apply a best fit line over the voltage curve thermistors output to get the Noland product to work; I think I wrote that up.
Does it track temperature from cold to hot or is the cold inaccurate?

Tom

Unfortunately, due to lack of documentation, I'm not really sure what the math is. But once I measured the temps and correlated that to the G2's raw data point, one button push did the calculation. My "understanding" is this is a linearazation of the data a similar calculation to what you did (I've learned a lot from you on CSR so again thank you).

"Does it track temperature from cold to hot or is the cold inaccurate?" I think what you asking is does this lineralize the data? The answer to best of my limited knowledge is yes. If this is not what you were asking clarify and I'll get you an answer.

In talking with Skybolt, he made it more accurate with more datapoints (I think he measured every 10 deg). I also need to add the hottest point (running under load), but I need an assistant to run the boat while I measure the temps. However, because these sensors resistance curve is flatter at the hotter end, I would expect more accuracy at the hot end of the spectrum, even beyond where I measured.. My next job is to go back and validate what I have.

One thing I understand the Chetco can do and the reason I chose it over the Noland, is that the Chetco Digital unit can bias its sensors with a regulated voltage getting rid of a source of error and frustration. However, I am not setting this up that way at this time. Currently I have this connected to the existing gauges that use the variable voltage the boat produces. If I like the unit and it works well, I may move it to the engine room where I can connect directly to the senders in resistance mode (selectable on the inside of unit with a dip switch). That would give me the most accurate results, but I'm not ready to give up the gauges just yet.

So far, I like the unit but documentation leaves a lot to be desired.
 
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Great detail. Sure I'll have detailed questions when I start this.

MM

My understanding is this can be applied to a twin gas boat just as easily....easy being a relative term.
 
Tom

Unfortunately, due to lack of documentation, I'm not really sure what the math is. But once I measured the temps and correlated that to the G2's raw data point, one button push did the calculation. My "understanding" is this is a linearazation of the data a similar calculation to what you did (I've learned a lot from you on CSR so again thank you).

"Does it track temperature from cold to hot or is the cold inaccurate?" I think what you asking is does this lineralize the data? The answer to best of my limited knowledge is yes. If this is not what you were asking clarify and I'll get you an answer.

In talking with Skybolt, he made it more accurate with more datapoints (I think he measured every 10 deg). I also need to add the hottest point (running under load), but I need an assistant to run the boat while I measure the temps. However, because these sensors resistance curve is flatter at the hotter end, I would expect more accuracy at the hot end of the spectrum, even beyond where I measured.. My next job is to go back and validate what I have.

One thing I understand the Chetco can do and the reason I chose it over the Noland, is that the Chetco Digital unit can bias its sensors with a regulated voltage getting rid of a source of error and frustration. However, I am not setting this up that way at this time. Currently I have this connected to the existing gauges that use the variable voltage the boat produces. If I like the unit and it works well, I may move it to the engine room where I can connect directly to the senders in resistance mode (selectable on the inside of unit with a dip switch). That would give me the most accurate results, but I'm not ready to give up the gauges just yet.

So far, I like the unit but documentation leaves a lot to be desired.
So, appears it simply draws a line between points and interpolates a relationship between temp and voltage; the more points of data the more applicability to a thermistor curve and consequently the more accurate. If this is true I would recommend you remove from the engine the temperature sensor and put in a pot of water then measure resistance and water temperature concurently as you heat the water to boiling; that is what I did. Then you can calculate the voltage measurements to load into the Chetco.
 

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