• Welcome to this website/forum for people interested in the Morgan 38 Sailboat. Many of our members are 'owners' of Morgan 38s, but you don't need to be an owner to Register/Join.

Holding tank monitor

Warren Holybee

Active Member
I had the electrosense monitor, but it failed. The Cat5 wire was not outdoor type, and in the bilge it cracked and shorted out. I otherwise really like the monitor, it worked well and was trouble free until that happened. Electrosense is now out of business.

I bought a scad monitor and the internal tank sensor. Nice idea, with a pipe that is inserted into that tank, with foil strips inside, instead of having foil strips on the side of the tank like many monitors use.


Trouble is, I am struggling to get it to calibrate. After cutting the sensor to the correct length, I tested it in a bucket and it seemed fine. But in the actual tank I am getting a calibration error. At this point I don't have confidence that it will be trouble free, and since there is no way to know how full the tank is to properly calibrate it, I've spit water out the vent, and still can't get it to work.

Anyway, other than the no longer available electrosense, what are others using? There seem to be very few options, short of cutting a bigger hole in the top of the tank for a standard 5 hole SAE mounted type.
 

Brian_Burk

New Member
My wife and I are new owners of a 1978 Morgan 382 (SV Samba) and are also looking for drop in option for the holding tank sensor. Electrosense seemed to the be consensus until late. I too am interested in hearing what folks have found to work a without modifying the original plug.

@Warren Holybee - Is the SCAD sensor you linked a drop in replacement to the original plug?
 

Warren Holybee

Active Member
My wife and I are new owners of a 1978 Morgan 382 (SV Samba) and are also looking for drop in option for the holding tank sensor. Electrosense seemed to the be consensus until late. I too am interested in hearing what folks have found to work a without modifying the original plug.

@Warren Holybee - Is the SCAD sensor you linked a drop in replacement to the original plug?
Very close. The SCAD is 1" NPT, so only a 1" to 1.25" NPT adapter is needed. The sensor can be cut to length.

I think I have it working at least "good enough" but need to fill and empty the tank a few times to be more comfortable. Calibrating it in a bucket doesn't work. It works fine in the bucket, but in the tank gives a calibration error. What I did (which wasn't fun) was remove the sensor and leave the tank open. Empty the tank. Put the sensor in and do the empty calibration, then remove it and fill the tank, looking in the hole to not over fill it. Then put the sensor in and do the full calibration.

Now, it seems there is about 1/4 to 1/3 tank before the gauge reads any more than empty, but it did seem to read full at the correct time. As long as I know I am getting close to full, and when it is completely full I consider that "good enough" It is possible I cut the sensor a bit short.

But given how difficult it was I need to test it some more before I am comfortable with it. I will try and do that this next weekend. If it proves to work, I would have to recommend this as the best option for our difficult tank situation.
 

Brian_Burk

New Member
Thanks, Warren.

Out of curiosity, how did you wire the new sensor? Did you split power off an existing circuit in the head? I am thinking how best to do it and tying into the existing shower pump circuit doesn't seem too hard. I might be able to get power out of the existing holding tank sensor which is currently dead. But I am not sure where it is dead, a multi meter would be able to solve that quickly.
 

Warren Holybee

Active Member
I mounted the meter near my electrical panel. It is powered directly off that panel through an inline fuse. Then 3 wires go from the meter to the sensor. If I mounted it in the head, I would do it the same way, and run new wire from the panel to the head. It's not a hard run. There is conduit from the locker under the chart table through the settee to the locker across from the head. From there there is a passage to the mast bucket, and then up into the head cabinet. You would need to pull 5 wires, 2 for power, and 3 for the sensor, which instead of going to the panel would exit the conduit and go down into the bilge.
 

terry_thatcher

Terence Thatcher
I have been afraid to take the old sensor out for fear I would break something never get the hole covered up. Plus with a 6' draft, my bilge floor is waaayyy down there.
 

Warren Holybee

Active Member
I have been afraid to take the old sensor out for fear I would break something never get the hole covered up. Plus with a 6' draft, my bilge floor is waaayyy down there.
For sure, buy a 1.25 npt plug and have it in your other hand. Get the plug in ASAP to hold the smell where it belongs. It came out pretty easy with a set of channel locks, and seals well only being screwed in hand tight. You could probably fabricate a very long "socket" with a piece of pipe.

If you use the holding tank with any regularity, you really need more than a light that turns on only after it's so full you can no longer use it.
 

Warren Holybee

Active Member
Well, the SCAD monitor is a failure, I hope no one else here bought one. :(
It is a great system, but doesn't work with the sensor submerged in the bilge. The more water on top of it, the lower the reading it gives. Enough that with 6" of water (just about the point my bilge pump turns on) it will always read empty. I had been fighting trying to get it to calibrate before I had the "ah ha" moment and turned on the bilge pump and watched the meter go from empty to full. (with a full tank)

Anyway, I am building my own. I am working on a building a new sensor like the electrosense came with, but I am using waterproof direct burial cable instead of cat 5. Because I was stupid and tossed the electrosense panel when I disposed of the broken sensor, I ordered this from Amazon which I think will work: Amazon.com: KIB 12 Volt RV Monitor Panel 2 Tank White | M20VW: Automotive. If it doesn't work, I'll have to build my own.
 

Warren Holybee

Active Member
It works, and I am happy with it! I might like to build my own panel later at some point, but the cheap panel from Amazon works fine.
Construction was as follows:

I bought five 1/8" stainless rods, a few feet of sprinkler wire, and a PVC 1-1/4" NPT to pipe adapter. I also bought some special stainless flux and a solder pot to aid soldering to the stainless rod. I have never soldered stainless before, and this made it quite easy.

Melt solder in the pot. Dip the rod in the flux, then dip in the melted solder, to tin about 1/2" of the end of the rods. Solder the wires to each of the rods. Punch 5 holes in a circle in a cardboard box, sized to fit in the PVC fitting. insert the rods. To both seal the bottom from leaking, and to provide release from the epoxy, I used coax seal (butyl rubber) around the rods on the cardboard box. Then I positioned the pvc fitting over the rods and pressed it into the coax seal. I adjusted everything to my liking. I filled the fitting with 2 pours of epoxy. I used west systems with 206 slow. I used slow because the large mass of epoxy could get too hot and go off too quickly with 205. Each pour was hard in about 1.5 hours.

The result is as professional as the electrosense that failed, but with waterproof sprinkler wire is much more durable. I really wish I had done this when the electrosense broke, as that would have been the perfect solution.

The cheap meter from Amazon has measurements in 3rds. Empty, 1/3, 2/3. full. I wish it were quarters, but it will do. I cut the rods to work as quarters, so my meter will really be Empty, 1/2, 3/4, Full. As I mentioned, I will probably make my own panel at some point. The amazon meter uses a wiring harness adapter, which seems to just be a few resistors of different values (from 0 to about 200k) for the different tank levels. All paralleled together, the result is that only 2 wires to the panel are needed, with a varying resistance depending on level.

I expect that this will be the last holding tank sensor I will need. :)

IMG_20210807_225651064.jpgIMG_20210814_105317973.jpgIMG_20210814_105334526.jpgIMG_20210814_105342895.jpgIMG_20210814_105407041.jpg
 

datswite

Ken Ferrari
It works, and I am happy with it! I might like to build my own panel later at some point, but the cheap panel from Amazon works fine.
Construction was as follows:

I bought five 1/8" stainless rods, a few feet of sprinkler wire, and a PVC 1-1/4" NPT to pipe adapter. I also bought some special stainless flux and a solder pot to aid soldering to the stainless rod. I have never soldered stainless before, and this made it quite easy.

Melt solder in the pot. Dip the rod in the flux, then dip in the melted solder, to tin about 1/2" of the end of the rods. Solder the wires to each of the rods. Punch 5 holes in a circle in a cardboard box, sized to fit in the PVC fitting. insert the rods. To both seal the bottom from leaking, and to provide release from the epoxy, I used coax seal (butyl rubber) around the rods on the cardboard box. Then I positioned the pvc fitting over the rods and pressed it into the coax seal. I adjusted everything to my liking. I filled the fitting with 2 pours of epoxy. I used west systems with 206 slow. I used slow because the large mass of epoxy could get too hot and go off too quickly with 205. Each pour was hard in about 1.5 hours.

The result is as professional as the electrosense that failed, but with waterproof sprinkler wire is much more durable. I really wish I had done this when the electrosense broke, as that would have been the perfect solution.

The cheap meter from Amazon has measurements in 3rds. Empty, 1/3, 2/3. full. I wish it were quarters, but it will do. I cut the rods to work as quarters, so my meter will really be Empty, 1/2, 3/4, Full. As I mentioned, I will probably make my own panel at some point. The amazon meter uses a wiring harness adapter, which seems to just be a few resistors of different values (from 0 to about 200k) for the different tank levels. All paralleled together, the result is that only 2 wires to the panel are needed, with a varying resistance depending on level.

I expect that this will be the last holding tank sensor I will need. :)

View attachment 8604View attachment 8605View attachment 8606View attachment 8607View attachment 8608

That's awesome, dude! I'll definitely keep this in mind if my Electrosense ever fails. Do you think the original Electrosense panel would work with your design?
 

Warren Holybee

Active Member
Yes, it would work. The only real between mine and the electrosense is that I used waterproof direct burial wire (sprinkler wire) instead of cat5. The insulation of the cat5 dried out and became brittle, and broke off the top of the sensor. But otherwise it is the same basic construction.
 

Brian_Burk

New Member
@Warren Holybee Do you have the lengths of the rods you used? I too recently installed a SCAD sensor which seems to be working to some degree. I never get more than an inch or so of water in the bilge and am hoping the top of the sensor is high enough to not be affected. Readings have been suspicisouly low though so time will tell.
 

Warren Holybee

Active Member
I cut the rods to 16", 12", 8", 5" and 2" - measured from the bottom of the fitting after it was all assembled.
16" being the bottom of the tank, and the others being 1/4 tank, 1/2, 3/4, and full.

If you keep the sensor top dry, the scad should work fine. My auto bilge pump comes on at about 6", and turns off at 1". It seems ok at 1". I actually think it may be the wires that are a problem. The tiny thin wires having a capacitance to the water when submerged. Or even passing current because they are not submersible wires.

You can test the scad sensor, or if you know some basic electronics interface it to some other meter. Apply 12V to the red and black wires, and the blue wire will be a voltage corresponding to the level. Roughly 0-5V, but not really depending on how short you cut it. Anyway, I hooked it up to test, and watched the voltage drop as the water got deeper. If the sensor had been made with better wires, it probably would have worked. You can also wrap foil around it to test. I really like the scad, its the crappy (pun intended) location that is the problem.
 

Brian_Burk

New Member
Sounds like the key to the SCAD sensor is keeping the wires, that are not designed to be submersed, dry. I'll have to brainstorm some ideas but since I usually only need to avoid an inch or two at most, I might be able to concoct something to extend the top of the sensor a couple inch upward. Maybe a short piece of PVC pipe placed on top of the sensor filled with epoxy? Heat shrink tubing with liquid electrical tape to seal the ends? Keeping a sponge nearby to remove the last inch of water when taking a tank reading?
 

Warren Holybee

Active Member
I special ordered a sensor with longer wires to get the connection out of the bilge, but they couldn't make one with heavier wires. I tired a number of possible fixes, but they all failed after a short time. Now that I think about it, maybe I had it wrong. Maybe instead of longer wires, cut them is close to the top of the sensor as you can, splice to something more appropriate, and encase the top of the sensor at the splice in epoxy.

Or, just keep the bilge dry. My pump doesn't turn on until about 6", and the A/C adds about 6" per day. So that wasn't going to happen in my case.
 
Top