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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
 
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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
 
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
 
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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?
 
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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.
 
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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.
 
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 ...
 
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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.
 

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