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Fresh Water Tank Leak

Discussion in 'Technical Discussion' started by JWY, Jan 28, 2021.

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  1. JWY

    JWY Senior Member

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    Situation: Yacht has a stainless steel fresh water tank. There is corrosion on one corner and it "weeps." Since the water drains/drips into the bilge and there is a smaller secondary isolated water tank, the owner isn't particularly interested in tearing out the whole tank for replacement. There is no inspection plate.

    Solutions: Should he cut open an area so the interior can be inspected and perhaps spot welded? Is epoxy coating a possible solution? Bladder insertion? Or does he need to go for the big fix of total tank tear-out and replacement?

    I would appreciate any expertise, experience, or advice on how to approach what isn't really a problem today, but might become one down the road. Or maybe not? So far, three years and no worsening.

    Thanks!

    Judy
  2. Pascal

    Pascal Senior Member

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    Bladder won’t work because the tank most likely has baffles inside... if the hole is small one try to clean any corrosion, rough up the stainless and use thickened epoxy to patch it. If the hole is too big they may need to use some glass. I wouldn’t do that with a fuel tank but with water they don’t have anything to loose.
  3. bayoubud

    bayoubud Senior Member

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    J-B weld WaterWeld an epoxy putty for that type repair. Used some today to patch a bronze pipe raw water manifold.
  4. Capt Ralph

    Capt Ralph Senior Member

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    The better repair would be to find, access and weld repair the leak.
    A patch from the inside with food grade sealant would be the next idea.
    Where is the boat?
  5. Pascal

    Pascal Senior Member

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    If the leak is a the top... sure. But if it s at the bottom can you safely weld against a fiberglass floor?
  6. NYCAP123

    NYCAP123 Senior Member

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    Before speculating on what and how to repair why not take off the hose and send a camera in. You may find nothing but a pinhole that can be closed up with a little JB Weld or you may find the entire interior corroded, but then you'll know if it's an easy fix, a complicated fix or a total replacement. Depending on size, placement, damage and local welding and labor rates replacement could be cheaper than repair.
    Last edited: Jan 29, 2021
  7. NYCAP123

    NYCAP123 Senior Member

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    No you can't.
  8. JWY

    JWY Senior Member

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    Thanks for the responses and suggestions!

    Answers to questions so far: Of course the leak is at the bottom. Does the buttered side of the bread ever fall face up? The boat is in Ft. Lauderdale.
  9. mapism

    mapism Senior Member

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    It takes a fair degree of luck to reach the exact leaking spot with an endoscope, inside a baffled tank.
    Still, depending also on how reachable the hose is, it might be worth a shot.

    Anyway, I wouldn't feel very optimistic on the overall conditions of the tank.
    Sounds like it wasn't built with the best stainless steel available, to say the least...
    That said, if it really didn't get any worse in three years, I'd be tempted to leave it as it is and keep it monitored.
    Judy, any chances that corrosion actually started from the outside, for some reason?
  10. Capt J

    Capt J Senior Member

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    In these situations replacing the tank is the only real fix.

    but epoxying another small sheet of stainless or fiberglass over the leak, usually works better than just epoxy by itself.
  11. bayoubud

    bayoubud Senior Member

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    Good idea to apply stainless metal sheet with the epoxy putty over the leak, would work well on an exterior patch too. You could shape the metal sheet hold a larger bead of epoxy over the leak, like a bottom corner.
  12. JWY

    JWY Senior Member

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    Epoxying another stainless sheet on the exterior assumes you can get underneath the tank, but I don't think it is accessible.

    Please keep the suggestions coming...
  13. Capt Ralph

    Capt Ralph Senior Member

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    Welding against a hull member or insulation of course would not be a good idea. A good examination of the area would be required here.
    A plan could involve even a partial de-install of the tank just for better and safer access.
    A shipwright and metal fab tech would be able to investigate this course after inspection better than we can from our keyboards.
    An after factory weld needs to be considered a patch also. The tank will always be concern in the future.
    Last edited: Jan 29, 2021
  14. Capt Ralph

    Capt Ralph Senior Member

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    I was thinking a patch from the inside, cloth or a metal scab over it could help. Then the water weight would always be pressing a tighter seal.
    From the outside, I would use rivets holding a metal scab and sealant in place.
    Last edited: Jan 29, 2021
  15. Capt Ralph

    Capt Ralph Senior Member

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    I agree.
    On some boats, the boat is built around the tanks. Probably why Judy opened this thread.
    As we have offered before, cut it out and install a few smaller replacement tanks tied together.
    Last edited: Jan 29, 2021
  16. Capt Ralph

    Capt Ralph Senior Member

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    There may be a reason for the failure other than the tank; Poor install on its bed or frame.
    In my boats, I have replaced a few bad tanks. Poor installs were half of the failures.
  17. Pascal

    Pascal Senior Member

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    So the weep is under the tank? Then it has to come out... but it’s all speculation without knowing where the tank is.

    I ve seen stainless steel water tanks under beds where it may just be a matter of cutting the bed to get the tank out. Usually the problem will be to get the the tank out of the room and boat if you want replace. In that case if the tank can be inspected and repaired it maybe the best option. Otherwise cut it up to get it out and replace by two smaller tanks that will fit in.

    it all depends on the boat.
  18. bayoubud

    bayoubud Senior Member

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    No mention of where tank is or if accessible on top. If the top is accessible to cut an inspection/access hole you could repair inside with J-B weld or 5200 even if damp before replacing tank. Seems there would be top access for replacing hose or gauge sensor.
  19. bayoubud

    bayoubud Senior Member

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    Judy, you could still repair with sheet metal plate on the inside if the top is accessible, it would actually better.
  20. Capt Fred

    Capt Fred Senior Member

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    A friend of mine has a leaking stainless steel water tank in his boat and he lives with it. No problems in the 20 years that I have known him. I would either live with it or try potable water grade epoxy.