How much water is in my fresh water tank?

[Jammer]

Originally Posted by Orion33

Hi Kelkara and Senojev, thank you for the suggestions of the water flow meters. Those sound like plausible solutions for my situation. My water pump is located on the forward bulkhead of the engine compartment. There is an easy access panel to this compartment making it relatively convenient to monitor the flow meter display on a use-significant basis. Consumer gadgets have come a long way in the last several years.

I would like to find a similar solution that could interface to my NMEA2000 data network thus allowing the data to be displayed on my helm multi-function display.

Anyone know of a water flow sensor that has NMEA2000 output?

If you're willing to go to all that trouble, just put a voltage sensor across the pump motor and monitor the accumulated runtime. When it gets to 10 minutes or whatever (you can run experiments by deliberately running all the water you have left down the sink once you get to the dock) you'll know you're out.

[JeffBurright]

Originally Posted by GILow

If you are reasonably handy with things like the Arduino range of controllers you can make all manner of tank gauges or even put a flow meter on the output and record the use that way.

Look at inductance, Time of Flight sensors etc for ways to apply a DIY microcontroller to the problem.

This is an interesting idea to use a time of flight sensor on an Arduino/ESP32. I see ebay has ToF sensors for dirt cheap, and an ESP32 is only ~$6. I wonder if you could drill a small hole through the top of your water tank and stick one of these sensors to the outside, beaming the laser through the hole, and wire the sensor via a USB cable to an ESP32 tied into the ship's 12v system through a 12v>5v buck converter. You could program a really simple arduino code to report tank capacity to a cheap LCD screen or even an HTML interface via the onboard wifi.

If you have multiple tanks, I suppose you could connect multiple sensors to the single I2C bus and devise a physical switch system that powers each sensor individually. You might also be able to assign multiple I2C inputs within the ESP32 code to gather all tanks at once, but I'm not sure.

Has anyone on here made one of these before who could report on whether it would actually work?

[GILow]

Originally Posted by JeffBurright

….
Has anyone on here made one of these before who could report on whether it would actually work?

Yep, I have. Why do you think I suggested it?

TOFL sensors are great, but combine it with a simple hinged float arm because most TOFL sensors are not good at spotting the water level.

[JeffBurright]

Originally Posted by GILow

TOFL sensors are great, but combine it with a simple hinged float arm because most TOFL sensors are not good at spotting the water level.

Ahh, yes I was wondering if it would be effective reflecting off a water surface. This fellow seems to have been able to make it work, but I had my doubts. I was considering some kind of floating mat like a pool cover, but I'm curious to see what kind of float arm you devised and where/how you attached it. I'd also be curious to know what kind of enclosures you devised for the sensor and microcontroller.

Since you've built one already, do you happen to have the Arduino code available to share? I think I've found my fall armchair project. Thanks!

[GILow]

Originally Posted by JeffBurright

Ahh, yes I was wondering if it would be effective reflecting off a water surface. This fellow seems to have been able to make it work, but I had my doubts. I was considering some kind of floating mat like a pool cover, but I'm curious to see what kind of float arm you devised and where/how you attached it. I'd also be curious to know what kind of enclosures you devised for the sensor and microcontroller.

Since you've built one already, do you happen to have the Arduino code available to share? I think I've found my fall armchair project. Thanks!

Sorry, I’ve moved on from the TOFL approach and I am playing with a new method that I’d actually like to commercialise. I probably won’t get rich with my idea but I live in hope.

Anyway, that link you found is as good code as any approach I’ve written.

For the float, just a length of stainless steel welding wire with a right angle at the hinge end and a fishing float at the other is all you need. Aim the TOFL sensor at the float and trap the right angled wire in a small nylon block. Basically the wire is there to keep the float cleanly in front of the TOFL sensor. Calibrate in much the same way as the link you found.

FWIW, the NodeMCU version of the Arduino has great built in Bluetooth and wifi which make broadcasting your tank level to some other device a real breeze. The NodeMCU devices have their own inter device communication standard so one can be at the tank and can broadcast the level to another in a convenient location for an LCD display. But that is, I admit, probably more complexity than is really needed.

I find Arduino projects are a bit of a rabbit hole really.

Edit: I do recommend you read up on how to clean up noisey sensor data. The TOFLs I tried all produced a rather jittery set of readings, but they smoothed out nicely enough using any of the common signal averaging approaches.

[Fintry]

Originally Posted by Orion33

Hi Kelkara and Senojev, thank you for the suggestions of the water flow meters. Those sound like plausible solutions for my situation. My water pump is located on the forward bulkhead of the engine compartment. There is an easy access panel to this compartment making it relatively convenient to monitor the flow meter display on a use-significant basis. Consumer gadgets have come a long way in the last several years.



I would like to find a similar solution that could interface to my NMEA2000 data network thus allowing the data to be displayed on my helm multi-function display.


Anyone know of a water flow sensor that has NMEA2000 output?

The Maretron FPM100 measures pressure, not flow, but you could install it in the line at the bottom of the tank and it will put the water pressure on the N2K bus. The Maretron DSM410 and others will translate that into inches of water or into % full if the tank is not tapered. I used them both for blackwater and for diesel on Fintry where the top of the tank was inaccessible. Not cheap, of course, but you asked for an N2K solution.


Jim

[Don C L]

Ummm, we are just talking about the water in an irregularly shaped container, 20 gallons of it, in a 25 foot boat, right?

[Greektherapy]

Buy a Topargee in line counter

[JPA Cate]

Originally Posted by Don C L

Ummm, we are just talking about the water in an irregularly shaped container, 20 gallons of it, in a 25 foot boat, right?

Where is it written that internet responses "should be" taking into account the size of the boat or the water tank? or that they should be fiscally reasonable? Have any of the respondents had a float-guage that was unreliable?

As I posted a long ways back, I think carrying an extra 5 gallons drinking water in a transparent container is the way to go. Cheap, easy to do; refills can be done at home, and two people can manage on 5 gal for two days, anyway, time in which to pick somewhere to water up and do it all again. It's a trailer sailer! They'll probably be stopping for more supplies, too.

Ann

[Harryg]

The following may not be a solution to the OP's question but may be of interest to those with flexible water/fuel tanks. My flexible water tanks are installed beneath the brigedeck settees. It's not too difficult to lift the settee lids to check the water level but I find it easier to monitor the levels on my cell phone, particularly when filling through a deck fitting. My reasonably straight-forward solution for those technically inclined was to build an ultrasonic measuring device using cheap readily available components - based on an ESP8266 D1 Mini. The ESP8266 connects to my onboard 4G modem/router. I can then connect to the ESP8266 from anywhere via a Telegram bot. I measure the distance between the tank surface and the ultrasonic transducers mounted underneath the settee lid, then convert the distance to a percentage. Minimum distance (100%) ie. full.

[Don C L]

Rube Goldberg would love this thread!