Water tank monitor for Al tank

[Epicurean]

In an Al boat I have integral (metal) water tanks below the floor with no openings except the outlet and the fill, which is on deck. Is there some sort of monitoring system I can install without drilling a hole? The only times I know the amount of water is when it's empty or full.

[Joh.Ghurt]

No, as fas as I know there isn't a way without drilling. The best option is to install an SAE-5 stud mounting plate on top and get some ultrasonic gauge like this.

[Epicurean]

Thanks. You may well be right. I did see something that mounted on the outside of non-metal tanks.

[noelex 77]

The Tank Tender system only needs a very small hole (around 3mm from memory).

[tkeithlu]

Is the side of your tank visible? If so, a sight gauge is the simplist - no moving parts and no electricity.

https://www.mcmaster.com/liquid-leve...el-indicators/

[Joh.Ghurt]

Originally Posted by tkeithlu

Is the side of your tank visible?

That's a nice idea, but with the original poster stating it's an integral tank, there's a good chance the visible side of the tank is the outside of the hull.

On the other hand, it would have some charm to keel-haul your darling to check the water tank level after than 30 minutes shower she took.

[Uncle G]

If you fit a water meter in the outlet pipe from the tank and log the reading when you fill up you'll be able to tell how much water you've used since then - and so be able to work out how much is left (once you've gone from full to empty to see exactly what the capacity of the tank is)

[mickand]

Google Gobius - they make external monitors that pulse an ultrasonic signal into the tank at any time interval that you choose. I have one on my plastic waste tank and it's simple, just stick it to the outside of the tank. wire it to 12v and bluetooth it to your phone.
Gobius claim that it will work on tanks of any construct.

[CarinaPDX]

Originally Posted by noelex 77

The Tank Tender system only needs a very small hole (around 3mm from memory).

IIRC it is a #6 thread. I drilled and tapped the top of the aluminum fuel tank and screwed in the sensor - no need to get at the inside for a nut if done this way. The Tank Tender is one of the few systems aboard Carina that has been there and worked flawlessly for 40 years with zero maintenance or problems. It is not cheap but it is worth every penny. The basic system is (or at least was) available for either up to 4 or up to 10 tanks, just by adding on the plumbing, and is fine for mixing water, fuel, and holding tanks. I highly recommend it.

Greg

[s/v Jedi]

You can install a pressure sender at the low point (using a Tee fitting at the tank connection where the freshwater pump picks up). This can be connected to a Maretron 6-channel pressure monitor, which can translate it to tank levels.

This is a modern version of the tank tender, using the same principle.

[Epicurean]

Jedi, I'll look at their sensors and see if anything fits. I looked up Gobius and that's what I was hoping for. Does it work well on an integral tank in a metal boat below the waterline? I have to investigate. Thanks.

[Epicurean]

Originally Posted by mickand

Google Gobius - they make external monitors that pulse an ultrasonic signal into the tank at any time interval that you choose. I have one on my plastic waste tank and it's simple, just stick it to the outside of the tank. wire it to 12v and bluetooth it to your phone.
Gobius claim that it will work on tanks of any construct.

That's what I was hoping for I'm not sure how well it will work on my integral metal tanks below the waterline. Thanks!

[noelex 77]

Originally Posted by CarinaPDX

The Tank Tender is one of the few systems aboard Carina that has been there and worked flawlessly for 40 years with zero maintenance or problems. It is not cheap but it is worth every penny. The basic system is (or at least was) available for either up to 4 or up to 10 tanks, just by adding on the plumbing, and is fine for mixing water, fuel, and holding tanks. I highly recommend it.

Another strong recommendation. I have had this system on two yachts over 14 years and it has been both super accurate and reliable. It requires no electrical connection. This has advantages especially for metal tanks.

[Epicurean]

Thanks. I'll look into that, too. But my preference is to not drill holes in my boat!