• 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.

Tank Level Monitoring

mpearson

Mark Pearson
Staff member
Howdy Morganeers. I hope everyone has stayed healthy & happy during these strange COVID times? We feel very lucky to be both, and to be getting good use out of Zia.

I've been considering putting in some tank sensors for both water tanks, fuel tank, and possibly holding tank. Has anyone done something like this? I know there are threads here on Holding tank monitoring. I think the latest is this:


I'm thinking of a Blue Sea tank monitor like this:
1612543156383.png

And putting this display and the sending unit's power all on one 'Tank Monitoring' breaker. So when it's turned off there is not the very small power draw of the senders & display. Blue Sea also makes sonic senders for diesel, water & waste.

I know this would not be accurate when underway & in waves, but I don't really care about that. Just rough levels when we are settled down would make me happy. I'm a little tried of needing to move things and pulling up cushions, opening caps to see levels. It could be that I'm lazy too. I think we will be getting a watermaker too, and it will make it easier to monitor the water tanks as they fill.

Any insight/feedback would be appreciated.
Cheers,
-Mark
 
Last edited:

jimcleary

James M. Cleary
Mark

When we installed the new holding tank in the V-Bunk we also installed a sensor from Electosense. There has been no issues with the sensor and I am sorry to hear that they are no longer in business. The Blue Sea unit you show looks promising. Nice to have multiple tanks on one monitor. Let us know how your install goes. With the Electrosense unit I had to give them the tank dimensions, Depth and Volume, so the probe could be set properly.

Jim
 

Warren Holybee

Active Member
I have the older Blue Seas vsm-422, which I use for battery and power monitoring, and would love to use for tank monitoring. Do research on the sensors. The Blue seas sensors require the tank bottom not be sloped, so they will not work with our water tanks, even the fuel tank might have a slight slope. So, I currently don't have monitoring of my water tanks, but would if I could find a sensor that would work with the blue seas monitor.

Scad internal sensors are the best I can currently find but they will not work with the blue seas monitor. I had some initial calibration issues with my holding tank, but it _seems_ to be ok now. They also custom built me a sensor with longer leads, so that I wouldn't have a connection under water, always a plus when a company will provide that service.

TM™ Tank Monitors | Technologies LLC (scadtech.com)
and here is the internal sensor
SCAD Internal Tank Sensor - e Marine Systems (emarineinc.com)
 

mpearson

Mark Pearson
Staff member
Oh geez - thanks Warren! I totally missed that the sensors didn't work with sloped bottoms. That would have been embarrassing. Kind of makes sense since it's sonic. Probably doesn't get the echo back & reports it as being full.

I'll check out those SCAD sensors & others.
 

mpearson

Mark Pearson
Staff member
Looks like Maretron makes some sonic sensors that can be mounted in a 'Focus Tube' to reduce the amount of sloshing and get around the need for a flat bottom. They cost about twice what the other sensors cost, but are NMEA 2k, so we can display on our chartplotter & other displays. And thus save the cost of the display unit. That seems nice. And they are powered by the N2k backbone so I wouldn't need to worry about it slowly draining the battery when we are anchored someplace for a while. And you can calibrate them for oddly shaped tanks (like our fuel tanks!).

Has anyone used this? below is diagram of the focus tube.

1612559125209.png
 
Last edited:

terry_thatcher

Terence Thatcher
Mark: I installed a tank tender for my main fuel tank. Requires you drill and tap a small hole in the steel tank top. I am very pleased with it. Might be hard to do the install in the bilge/keel holding tank. For my water tanks, I just unscrew the inspection plate and look in. Low tech, but it never fails.
 

jimcleary

James M. Cleary
For the water tanks, Dana has both port and stbd, years ago I filled each tank with a five gallon container. After each fill a 3/8" dowel was marked at the level. Now each morning when we are cruising we sound the tanks via the inspection plates with the dowels. Quite accurate and easy.

Jim
 

jimcleary

James M. Cleary
When you put the dowel through the inspection plate opening, just let it slide down to the lower inboard corner of the tank. That way it is always reading from the same place and is always accurate.

Jim
 

jimcleary

James M. Cleary
I am rather anal when it comes to the systems on the boat. From my time as a machinist mate on WWII vintage destroyers we were schooled to take hourly readings on the engine room status. Each morning when we are out cruising I take 12 morning readings so I know where we stand. The 12 stats are: Amps down on the house bank, Fuel level, Cabin temperature, Stbd water tank level, Port Water tank level, Total water level, Fuel (diesel) in the Espar heater tank, Frigaboat (fridge) temp, Holding tank level, Barometer reading, Visual inspection of the bilge, Visual inspection of the engine. This whole routine takes about 5-8 minutes. The numbers get noted in the log book. Then we're ready for the day.

I am a firm believer in the teachings of Capt John Bond, who was the commander of the Naval Academy Sailing program. His motto was " You get what you inspect, not what you expect".

Jim
 

mpearson

Mark Pearson
Staff member
Those focus tubes I was considering require 2" of clearance above the tank. We don't have anywhere near that space for the water tanks. So it looks like we will continue visual readings - I guess it's not that onerous. I think it's what they call a "First World Problem". ;)

We have an inspection checklist like yours Jim, that we also log. Part of being a proper boat owner/operator, we think.

So, Terry, when you run your watermaker, you probably open the inspection ports of the water tanks to watch the levels?
 

mpearson

Mark Pearson
Staff member
Warren - those look like they would work well. Simple, and if they get gummed up, easy enough to clean. I might give that a shot. Which Blue Sea Monitor do you have? The one that does State-of-Charge for your batteries too? Amps? Thats the one I'm considering now.


The above one (Blue Sea 1850) is NMEA 2000, which has me a little concerned about needing to power up the backbone if I only specifically want the amp/state-of-charge functions at a particular time. Seems that could be a waste of power if I want to only monitor the amps/state-of-charge while out anchored away from shore power. So a possible more energy efficient alternative would be to get their separate Tank (Blue Sea 1839) and DC Multimeter w/State of Charge (Blue Sea 1830). I could put those (and their senders) on a separate breaker and just turn them on when I wanted to monitor the tanks or battery state/amperage.

Or maybe I'm being too concerned about the NMEA backbone power draw. I think I'll go measure what kind of amperage it draws when powered up.

Has anyone been inside the Holding Tank enough to know if the bottom of the tank is sloped? Or mostly horizontal?
 
Last edited:

Warren Holybee

Active Member
Warren - those look like they would work well. Simple, and if they get gummed up, easy enough to clean. I might give that a shot. Which Blue Sea Monitor do you have? The one that does State-of-Charge for your batteries too? Amps? Thats the one I'm considering now.


The above one (Blue Sea 1850) is NEMA 2000, which has me a little concerned about needing to power up the backbone if I only specifically want the amp/state-of-charge functions at a particular time. Seems that could be a waste of power if I want to only monitor the amps/state-of-charge while out anchored away from shore power. So a possible more energy efficient alternative would be to get their separate Tank (Blue Sea 1839) and DC Multimeter w/State of Charge (Blue Sea 1830). I could put those (and their senders) on a separate breaker and just turn them on when I wanted to monitor the tanks or battery state/amperage.

Or maybe I'm being too concerned about the NMEA backbone power draw. I think I'll go measure what kind of amperage it draws when powered up.
I have the discontinued VSM-422 Vessel Systems Monitor VSM 422 - Boxed - Blue Sea Systems

The M2 Replaced it. I think the NMEA connection is optional, and allows the sharing of all the sensor and SOC data to a chartplotter. Otherwise, I think it is very similar to mine, with some graphical changes. I note that the new one still doesn't support lithium SOC profiles. I am upgrading to Lithium this year, so depending on how poorly the Blueseas performs, may need to replace it with something else, or 2 something else's since none of the good SOC monitors seem to do tank monitoring.
 

mpearson

Mark Pearson
Staff member
Warren - you're right. Digging thru the manual, it says the M2 is powered by the DC connection, and not powered thru the NMEA connection. However, I noticed the M2 only does 2 tanks (their Tank Monitor handles 4). Ideally I'd like to monitor 4 tanks (diesel, 2 water, holding tank) if I can find a good sender for the holding tank. So I still might go for 2 separate meters. I'm wondering if Blue Sea's sonic tank sender might work for the holding tank. I've never seen the bottom of our holding tanks to know if it is somewhat flat. On the rough design drawings it looks like it's curved. Also don't know if the Blue Sea sonic tank sender's top would be okay if it was submerged in bilge water. I sort of doubt that.

I'm surprised the M2 doesn't have lithium profiles yet. The M2 is quite new and lithium is no longer "super new". The good thing is that you can update the firmware with a micro USB, so I'd guess when they add lithium it'll just take a firmware update.
 
Last edited:

Warren Holybee

Active Member
My VSM422 does three tanks, with the option of having the 3rd tank be a bilge pump counter-which I really like as when I arrive at the boat I know if the pump has been operating. Since I have Fuel and Waste monitors elsewhere, that works ok for me.

I sent an email to support asking about Lithium. It seems it would be very easy to add, there really should be a way to manually enter the peukert value, but there is not. Both temp compensation and charge efficiency can be manually entered, so it seems strange to not allow a user peukert value. I never was able to make it accurate even with my lead acid because I couldn't tweak that. My VSM422 also has a way to update the firmware, but no updates were ever offered, so I hope that they don't discontinue development on the M2.

Bummer, as there isn't anything else on the market that is so complete. Victron and Balmar both make great SOC meters, but I would need to supplement with a tank monitor and bilge monitor, or leave the VSM in place but not monitoring SOC. Frankly, I don't have enough panel space for any more meters.

Submerging a tank sensor under water is a big issue. I think few are really designed for it. It killed the wiring on my electrosense sensor, and I don't have great confidence with the scad sensor wiring. They were willing to build a custom sensor with longer leads, but not willing to upgrade from 18AWG to 14AWG.
 

Warren Holybee

Active Member
From Blue Sea support:

Warren,

Thank you for the question. None of our current meters have Lithium profiles the 1850 has one in the development stage but that version will be over a year away.
Please ask if you have any additional questions.
Best Regards,

Blue Sea Systems Tech Support


I'm not able to wait that long, so I will be adding a Victron BMV-712 to my panel. My Blue Seas VSM will remain for AC power and Tank monitoring.
 

mpearson

Mark Pearson
Staff member
Interesting. Thanks for sharing that, Warren.

Have you ever posted on here what your drivers are for moving to Lithium? Last year when I was replacing our lead acid batteries I thought about Lithium, but I couldn't cost justify it. They have some awesome traits, though.

If you ever have the time, can you post a separate thread about Lithium Batteries? Unless you have already and I missed it. ;)

Cheers!
 

terry_thatcher

Terence Thatcher
Mark, in response to you water maker question: I have two tanks. I can join them together if I want. Given that the water maker only produces 6-7 gallons an hour, I have never been too concerned with over filling the tanks. But, yes, I occasionally check water levels during H2O production if I am bringing the tanks up to near full.
 

mpearson

Mark Pearson
Staff member
After doing some more research, I purchased the senders that Warren had mentioned, with the intention of using them for diesel tank & the 2 water tanks. They arrived yesterday and they seem well built. I think they’ll work well (at least for a while!). Reasonably priced, too. Those will be so accesible they will be easy to clean, troubleshoot, etc.


I’m still debating what to use for the Holding Tank. Holding Tank senders are (obviously) tricky because of their propensity to get fouled up dealing with their foul contents. Ours are even more tricky because the top of the senders can be sitting in bilge water. So the top needs to be thoroughly waterproofed.

We’ve survived without a HT sensor for the last 9 years, so maybe we will just continue guessing & occasionally being wrong. ;)

I’m wondering if I got a normal sender and thoroughly sealed the top of it with some kind of epoxy-like material so that it was waterproof & had good waterproof electric connections. Back when we had our Perkins we always had some oil in the bilge & would have worried about that degrading the electric wires/connections, but with the shiny, clean new Yanmar, we don’t need to worry about that.

Whatever is used, I’m sure it would need to be removed and cleaned up on some kind of regular basis.

Any thoughts/advice welcome ...
 
Last edited:

rickdowe2

Richard Dowe
Morning Mark, somewhere I have stashed a simple diagram for a tank level indicator but is similar to the snapshot. Some you can make with just resistors, this one is with transistors. The probes of various lengths can be mounted in a removable 1 1/4'' plug. Stainless or copper Nickel welding wire comes to mind. A face plate can be made to your liking with different color LEDs and a momentary push button to see the level.
 

Attachments

  • IMG_1779.PNG
    IMG_1779.PNG
    2.5 MB · Views: 23

mpearson

Mark Pearson
Staff member
Resurrecting this thread, I installed the Blue Sea 1839 M2 Tank Monitor and the senders that Warren mentioned above. Everything seems to be working pretty well. It was a very easy install and the only real/hard work was getting the wiring run between the tanks (especially the forward tank!) and the M2 display. I ran the wiring to the forward tank the same time I was replacing the polybutylene water pipe to the tank. It would have been very difficult if I hadn't used the polybutylene to pull some wire through that run.

Below is a photo of the levels for the Starboard Tank, Bow Tank and Fuel Tank.

1659545255793.png

Our Holding Tank is not a concern now because we tore out the piping and replaced the head with a Composting Toilet. We really like the composting toilet, BTW. Super simple and zero odors.

I used a water meter to calibrate the depth/storage on the Tank Monitor, so it should be quite accurate. I haven't calibrated the fuel tank yet, so it still shows in percentages in the photo above. Optionally, you can have the monitor display in percentages or gallons/liters.

Note: At first, I bought the cheapest water meter on Amazon to calibrate the tank volumes. After I got strange volume readings I tested it against buckets of known volumes and it was highly inaccurate. I returned it and got a more expensive ($40) meter that was highly accurate according to my bucket tests. My forward tank has a volume of 30 gallons, and starboard tank volume is 51 gallons, for a total of 81 gallons.

In case anyone is considering this, the sender lengths I got were - Bow/Forward: 15", Starboard: 11", Fuel/Diesel: 9". These are supposed to be about an inch less than the tank depth at the location where you plan to mount them. In the case of the Starboard tank, I mounted the sender in the screwing access cap, because that was directly over the deepest part of the tank. I just added a wiring plug there so it could be unplugged before unscrewing the access cap. In the forward tank, I cut a new hole just aft of the access hole. For the fuel tank the sender fit perfectly into the SAE holes that are around the access hole on the tank.

This is hardly considered a 'critical/important' upgrade and I guess it is proof that I'm running out of important projects to do?!

It is very nice/convenient to tap a button and see the levels. Push button convenience! Very satisfying!

I was hoping that I could get a similar sending unit for pressure on my propane tank, then I could see everything in one spot. No such luck. I couldn't find one for pressure on a propane tank. There is probably a reason that I'm ignorant of ... like it will blow you up or something.
 
Last edited:
Mark, nice job. Ican see where this would make life a bit easier. Our tanks are marked 55 gal Starboard, and 35 or 40 gal forepeak. Can't remember but supposedly 9o gal total. That's a far cry from what you have found! Now Iwill have to start measuring and calculating, damn! 42 gal is hardly enough to get anywhere.
I'll get back to you.
Mitchell
 

mpearson

Mark Pearson
Staff member
Hi Mitchell - yeah, it was a cheap little meter I got on Amazon, but supposedly +/- 5% accuracy. I'm going to do a test fill of a 5 gallon bucket to see if the meter is in the ballpark or not. Yeah, the specs I see for other M38s on Yachtworld.com show 90 gallon water storage too.
 

mpearson

Mark Pearson
Staff member
News flash: the brand new cheap meter from Amazon is faulty. I just filled a 3 gallon bucket and the meter said it was 1.95 gallons. I'll post the correct gallons after I get a better meter. :( Or since good meters cost so much, I'll probably fill the tank using a 5 gallon bucket and tally the fills.
 
Well Mark, that's a little reassuring actually. LOL
AMAZON, Walmart to the world. I almost bought a meter there too, just put it off.
Thanks
Mitchell
 

Warren Holybee

Active Member
Awesome. I have yet to buy and install the sending units, but hopefully will in the next couple months. Too many other projects.
 

mpearson

Mark Pearson
Staff member
I got a more expensive ($40) water meter that was very accurate according to my tests on 3 and 5 gallon buckets. Now I'm fairly confident my forward tank has a volume of 30 gallons, and starboard tank volume is 51 gallons, for a total of 81 gallons.

Here is a photo of my contraption. Garden hose on left, and the right end goes into the tank. Note: many meters need to be horizontal like this to read correctly. The valve and angles weren't required, but made it easier and I already had them from previous plumbing jobs.

Zia Water Meter.jpg

I took a total of 30 readings on both tanks (combined) to get the calibration points I needed for the Blue Sea meter. It allows you to put in actual percentage full versus percentage depths on the sender units at 40, 60, 80, and 100 percentages. That way, it can display an accurate gallon remaining number based on the depth at the gauge. I graphed out my data in a spreadsheet and got the volumes for 40, 60, 80, 100 percent depths.

In case anyone else does this in the future, here are the results I used in the Blue Sea tank level meter:
1660402542926.png
 
Last edited:

Warren Holybee

Active Member
I got a more expensive ($40) water meter that was very accurate according to my tests on 3 and 5 gallon buckets. Now I'm fairly confident my forward tank has a volume of 30 gallons, and starboard tank volume is 51 gallons, for a total of 81 gallons.

Here is a photo of my contraption. Garden hose on left, and the right end goes into the tank. Note: many meters need to be horizontal like this to read correctly. The valve and angles weren't required, but made it easier and I already had them from previous plumbing jobs.

View attachment 8941

I took a total of 30 readings on both tanks (combined) to get the calibration points I needed for the Blue Sea meter. It allows you to put in actual percentage full versus percentage depths on the sender units at 40, 60, 80, and 100 percentages. That way, it can display an accurate gallon remaining number based on the depth at the gauge. I graphed out my data in a spreadsheet and got the volumes for 40, 60, 80, 100 percent depths.

In case anyone else does this in the future, here are the results I used in the Blue Sea tank level meter:
View attachment 8942
Nice.
 

terry_thatcher

Terence Thatcher
I am confident that our main fuel tank is TRUE 40 gallons. I have a Tank Tender and am having a hard time carefully calibrating it. It measures inches and the tank does not have 90 degree sides. At least, it flairs out in the upper portion. So each inch is not the same. ( I used to assume that was the case, but now I know otherwise. ) I may someday go to a fuel dock that is not busy with a low tank and take time to calibrate each 2.5 gallons. Right now I am stuck in Desolation Sound waiting for a new fresh water pump for my old Perkins. Not a bad place to be stuck, but I am tired of sitting at a dock rather than sailing. The Perkins always starts and runs well, but I am tired of bits and pieces breaking down.
 

Cliff Porter

New Member
When you put the dowel through the inspection plate opening, just let it slide down to the lower inboard corner of the tank. That way it is always reading from the same place and is always accurate.

Jim
I use a wooden yardstick. On my tank the stick is flush with the filler hole when it stops the bottom inboard wall in the tank. I emptied the tank. Mopped it out and poured in fresh diesel one gallon at a time and noted the inches on the stick on a laminated card stuck inside the nav table.
I would like to find a sensor for the water tank under the V-berth to close the circuit to an alarm so I know when it's full. I would put a toggle switch in series so it could be disabled while underway. I'm thinking a magnet on a float glued to the inside wall of the tank and a reed switch on the outside so there's no breach in the tank from a wire. Sort of how the low level sensor on a Kurig coffee maker works. When the magnet floats up the tube and comes close to the switch it pulls the strips together inside the switch to close the circuit and BEEEEP! I have a 180 db piezo that can be heard half way around the world. Now if I can just find the switch assembly. If I find one I'll get two and put a quieter low level alarm up by the sink. Once the tank runs dry it can be a bear trying to prime it, even with a new high capacity pump I installed this year. And YES the screen filter is clean.
I got a more expensive ($40) water meter that was very accurate according to my tests on 3 and 5 gallon buckets. Now I'm fairly confident my forward tank has a volume of 30 gallons, and starboard tank volume is 51 gallons, for a total of 81 gallons.

Here is a photo of my contraption. Garden hose on left, and the right end goes into the tank. Note: many meters need to be horizontal like this to read correctly. The valve and angles weren't required, but made it easier and I already had them from previous plumbing jobs.

View attachment 8941

I took a total of 30 readings on both tanks (combined) to get the calibration points I needed for the Blue Sea meter. It allows you to put in actual percentage full versus percentage depths on the sender units at 40, 60, 80, and 100 percentages. That way, it can display an accurate gallon remaining number based on the depth at the gauge. I graphed out my data in a spreadsheet and got the volumes for 40, 60, 80, 100 percent depths.

In case anyone else does this in the future, here are the results I used in the Blue Sea tank level meter:
View attachment 8942
Where did you get this meter? That's a nice "no batteries needed" solution.
 

terry_thatcher

Terence Thatcher
Cliff, would you share your fuel tank calibration. I could use it for my Tank Tender, which gives me measurements in inches and half inches. Thanks. On my water tanks, I just open the clean out ports and look in. I guess a gauge would be nice, however.
Mark, do you have to drill a hole to install the sending unit of the Blue Seas system or does it sit on top of the tank? Their web site doesn't explain very well. Could this bne used for the below bilge holding tank?
 

mpearson

Mark Pearson
Staff member
Cliff - do you mean the water meter? I got it at some internet store called 'Amazon'. If you search for "DAE AS200U-75" you'll see it. Or if you mean the Blue Sea tank level meter, I got it from Defender.com.

Terry - yes, I drilled a hole in the tank on the bow tank, and drilled a hole in the lid of my starboard tank. I used these holes to install the sender. Yes, I think maybe these would work for the below bilge holding tank, but I would encapsulate the portion that is outside of the tank with epoxy, I think, to make it more water proof. And use water tight heat shrink butt splices to connect. I think this would work for X years, until enough water seeped in to short it out. :) That's one of the reasons we got our Composting toilet: no more holding tank! no more odors! no more pump out stations covered in human and bird poop!

I was trying to figure out why I couldn't get a sender like these to measure propane pressure. From what I've been told, the pressure isn't really an indication of how much propane you have left. And in order to know the real remaining amount, you need to measure the weight of the cylinder. So I guess I'll continue my existing practice of picking up the cylinder, shaking it and feeling how heavy it is with my hands. How's that for Old School?
 
Last edited:
Top