Aft water running out

[Jonathon Truwit]

I found that my aft tank empties very quickly without using water on boat.  I have also found that after closing the manifold valve (pic one) the tank level is stable give or take a few percentage points.  I have looked at my connections in bathroom, inlcuding behind thru hulls accessed through door under toilet paper holder.  I have removed the forward split mattress from aft quarters and removed wooden tops so I could look at connections.  I reached up and felt aft tank and it was dry.  Only moisture is in the port side section in the little space (pic 2).  I did not feel water dripping, was running hose concurrently in aft water intake.  Would appreciate any thoughts.  

thanks

Jonathon 

Spiritus, sv 129

[Jonathon Truwit]

looks like Mac had not caught up with iphone for second picture

arrow is where section was moist.  seems to be between engine and shower

[Kenneth Oates]

I’ll take a stab at this one.  I think the aft tank is a little higher up than the midship tank and Archimedes was correct.  Your aft tank (the smallest one) is emptying into the midship tank if you have all the valves open at the same time.  By closing off the valve to the aft tank you stop this process. So you aren’t really leaking at all.  If you close off the valve and you still lose water, then you have a leak.

Ken Oates

oat...@gmail.com

Kshanti, #151

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[Jonathon Truwit]

Thanks, but I am losing 1/4 tank in 20 minutes max and not using water.  But I agree aft would be first.  I will do again tomorrow but be sure to stay on boat to confirm bilge going off.  The alert light in panel next to breakers sounded off, so I am thinking that was the bilge, but I did not hear it in aft quarter. 

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[Jonathon Truwit]

Oh, I needed to reread.  Maybe it is going to midship tank.  I can check to see if the percent fill is going up, if so you are correct.   I recognize the monitor is only but so accurate, but still if changing then I agree, then I need to figure out why alert when off while filling aft tank.

On Aug 9, 2025, at 4:30 PM, Kenneth Oates <oat...@gmail.com> wrote:

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[Jonathon Truwit]

Ken and Archemedes are correct!  Filled the aft to 95% and it fell to 63% as the forward tank filled to 100%,  Guess I never filled aft tank when forward tank was low.  Starboard tank is at 0 and did not change.  

Ken thank you for the education.  

Jonathon 

[Kenneth Oates]

Glad to help.  You know what they say, even a broken clock is right twice a day.

Ken Oates

oat...@gmail.com

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[Mark Hensley]

Blaise Pascal would be upset that Archimedes Principle is being attributed to this flow of water issue.  Archimedes Principle deals with displacement of a liquid, as when he immersed himself in a bathtub. Pascal was dealing with pressure which causes a liquid to seek its own level. The difference in liquid levels in the tanks connected through piping flows due to head pressure resulting in the flow from the higher level to the lower level.

I too have experienced the same issue on my boat because the piping valves were open.

Mark Hensley

Amphitrite #119

[Kenneth Oates]

Thanks, Mark.  I stand corrected, and I also now blame Pascal for having to close off my head sink and toilet stopcocks while on a starboard tack.

Ken Oates

oat...@gmail.com

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