How much water is in my fresh water tank?

[Orion33]

My Acadia 25 pocket trawler has a 20 gallon poly-tank that is fiberglassed to the hull, under the deck, and is inaccessible. Through a deck hatch I might be able to get to the tank outlet fitting, but the tank itself encased in fiberglass.


The water tank feeds a pressurized water system whose components are readily accessible.



I'd like to be able to monitor either the water volume in the tank or the water consumed. Any ideas?

[Bowdrie]

Where the outlet is you insert a Tee fitting, then from the branch of the Tee fitting you run a length of clear hose up to the tanks vent fitting.
Use another Tee at the vent end.
Now you will see the level of the tank water.

[Orion33]

I don't think I can get to the vent hose because it is embedded in the under deck hull structure. I understand your idea, and I like its simplicity but the location of the tank will probably prevent this solution from working. Thank you for the idea.

[Don C L]

I would suggest not using a pressurized system for 20 gallons of water on a 25 foot boat. It is easy to waste water with a pressurized system and with 20 gallons you don't have much to waste. I'd recommend going to a foot or hand pump. Whether you stick with pressurized or not, I think you'll need to keep track of every use if you are concerned about water level. I have a similar situation in my boat and mine holds 25 gallons in the keel (supposedly though I have never checked it to be sure.) Since the tank is not symmetrical I don't know how much help a clear tube would be even if there were access. You could try a dip stick that you mark yourself as you fill with each gallon.

In my own case I use the tank in the keel very sparingly since I like it to stay there for ballast, and I use mostly bottled water that is stored in hatches below the waterline in the bow for cooking and drinking. For bathing and rinsing I have 2 six gallon jugs that stow on the sole under the v-berth. That will last me about 2 weeks with two kids if we are very careful with it, including a couple shower/hair rinses. If I had pressure water I'd be using more electricity and more water. On a small boat there's not much room for waste.

[flightlead404]

Stick on external tank sensor?

[JPA Cate]

Interesting problem. If you can't figure out a way to access it with a dipstick (which is what we use for fuel tanks); or make an effective sight tube; what to do?

Maybe easiest and cheapest is a ~ 5 gallon jug, stowed under a berth for spare. Then don't worry about it, (because you won't run out), and you can make 5 gallons last a loooong time when you know it's your only supply.

Now, I'm thinking you don't usually go out for more than an overnighter. If this assumption is wrong, maybe you'd need two jugs.

As so monitoring, it would be a pita, but you could measure and tally up your usage for a whole tank, and determine your average daily usage. Which - if you don't mind doing it - would give you a rough idea. Divide by the number of POB each day, so you gain that knowledge. (If you train yourself to be very water conservative, you can get by for a long time on 1/2 gal/per day per person. But that is not including water for personal hygiene. One either uses sea water, or carries a sun shower, and when it's empty, it's all over, but you can monitor it visually through the clear polyethylene side.)

I agree with Don C L that using hand or foot pumps will help you to conserve water. And, it helps guests to "get it", if they have to carry the water jugs to the boat to put in the tank, too. People who go backpacking tend to have good water conservation skills.

Ann

[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.

[Kelkara]

I use a garden hose water meter on the hose to my foot-pump. It's not 100% accurate, but gives a good estimate of how much water I've used ... remember to reset it when the tank is filled.


Something like this:
https://www.amazon.ca/Orbit-56854-Ho.../dp/B0187BOFD6

[Senojev]

A simple water meter in the water line.

https://www.amazon.com/dp/B0BL37TN96/ref=syn_sd_onsite_mobileweb_0?ie=UTF8&psc=1&pd_rd_ plhdr=t

[Orion33]

Thanks Don, I like the dip stick idea. But my tank is fully encased in the hull structure with no fitting access for the stick. I've used foot pumps before and they are a good way to conserve water. I do carry a 6 gal. jerry can for enroute refill. It would be nice to know how my water consumption is progressing and how close I am to running out. More research is needed.

[Orion33]

Hi flightlead404, wish I had access to at least one side of the water tank. Your suggestion of stick-on water sensor is a great solution. I've used this before for a black water tank and it worked well. But this water tank is completely inaccessible. I think a water flow meter in the pump output line may be the answer.

[Orion33]

Hi Ann, thank you for your thoughtful consideration of my issue. My wife and I do mostly overnight trips, but are looking forward to some longer excursions between marinas. Knowing how much water remains in the tank and at what point we are in the trip would help us increase conservation or enjoy a little luxury, depending on conditions. Carrying an extra 6 gal jug does help keep the anxiety level low, but still would be nice to know the condition of onboard stores.

[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?

[JBP]

The "Tank Tender" only requires you fit a thin tube somewhere such that the tube terminates at the bottom of your tank. It uses water pressure to determine tank level. The official Tank Tender is hideously expensive, but you can get an RV version for much less.

https://tanktender.com/

https://horstmiraclegauge.com/

[Jammer]

Originally Posted by Orion33

I don't think I can get to the vent hose because it is embedded in the under deck hull structure. I understand your idea, and I like its simplicity but the location of the tank will probably prevent this solution from working. Thank you for the idea.

You can use a sintered vent instead, inexpensive and available from many sources.


Make the translucent sight line come up as high as possible in the cabin before connecting it to the sintered vent so that the vent stays dry. Depending on the water quality, you may have to replace the sight line periodically (every few years) has it becomes harder to read.