Leaking stainless steel tank

[Gjoa14]

Hi cruisers community

I am looking for helpful and/or creative ideas to fix my stainless steel water tank">fresh water tank. An overview:
1. I did not experience or test by myself that the tank is actually leaking - only know it from the previous owner. But because it is not the most reliable person, I would even be interested to test if the tank actually leaks. But that is difficult too, because...
2. The tank is in a very difficult accessible location in the bow and can not be taken out. (Except if I cut it out)

I was thinking about a food-safe epoxy to seal it from the inside. Here I also read that the food-safe one is not the best for sealing, so an idea could also be to use first a good sealing epoxy and then a food-safe one.
I don't dare to weld it by myself and also doubt if that's possible at all, even if an expert is doing it. But maybe someone here knows more about it.

I already heard a lot of recommendations for just buying a new tank, and sure that would be a solution, but I wish to first check if there is a way to repair the existing one

Maybe to explain the picture: the tank is a tetrahedron, so like a cone triangle and with the top down. The pre owner cut the top out, the cut out part is present.

Thank you all a lot of recommendations!

[model 10]

Do you know where the leak is? What was the plan for putting the top back on?
Seal the leak, glue and screw a plastic top on the tank?

[skipmac]

Had a similar problem with a previous boat, leaking water tank that was built into the boat.


I cut a large access hole in the top and cajoled a welder (with promises of a big tip and a case of beer) to hang down into the tank and weld the split seam from the inside, then weld the top back on. Still good when I sold the boat a few years later.

[S/V Adeline]

Make sure you find a welder who is an actual stainless steel welder. I would suggest a tig welder. Stainless is a different beast.
Fumes are toxic, of course he/she should already know that.

[Tetepare]

Don’t mess with it till you know it leaks. Put blue food dye in it, trace where it might come out and look for color.

[dennisjseidel]

I had a similar problem with my monel water tank. I removed it, scoured it really well, and patched the leaking seam from the outside with epoxy fiberglass. That was 10 years ago and it is still holding water today.

[Cheechako]

With the top cut out already, I would consider just getting a plastic tank or two that will fit in there. Or a bladder tank. Especially if this is a daysailor and not a live aboard situation.
I have to say though, I can't tell if that is a tank or what. The interior does not look like a tank, looks like the hull interior...? There appears to be a plywood(?) floor down there and the bow reinforcement etc...?
If it is a liveaboard situation, I suggest you find a better place for a tank than the bow if you can and just abandon that one. Under the cockpit? under the aft berth? under the setees?

[jharding]

There is a company called Muggy weld, check them out on youtube, they make different rods and pastes to weld(solder) stainless and aluminum with a propane torch. I fixed a stainless hot water tank that had pinhole leak, very easy and worked great. I also butt welded two pieces of aluminum together and could not break them apart, I can now fix a lot of things on my boat with a propane torch instead of hauling my tig welder.

[a64pilot]

I’d grind all the seams to get some “bite” and then epoxy.
I’d then cut a ring that is two inches larger and smaller than the opening, and slide it inside of the tank and either drill and bolt it to the tank top with sealer, or rivet. That way the original cut out will lay into the cut out flush. I’d attach it with blind nuts riveted to the ring I fabricated so that it can easily be removed in the future, with a non hardening sealer.
Just do not use nutserts or rivnuts, almost guaranteed they will spin when you go to remove the bolts or screws.

[rmlarson1098]

Originally Posted by Gjoa14

Hi cruisers community

I am looking for helpful and/or creative ideas to fix my stainless steel fresh water tank. An overview:
1. I did not experience or test by myself that the tank is actually leaking - only know it from the previous owner. But because it is not the most reliable person, I would even be interested to test if the tank actually leaks. But that is difficult too, because...
2. The tank is in a very difficult accessible location in the bow and can not be taken out. (Except if I cut it out)

I was thinking about a food-safe epoxy to seal it from the inside. Here I also read that the food-safe one is not the best for sealing, so an idea could also be to use first a good sealing epoxy and then a food-safe one.
I don't dare to weld it by myself and also doubt if that's possible at all, even if an expert is doing it. But maybe someone here knows more about it.

I already heard a lot of recommendations for just buying a new tank, and sure that would be a solution, but I wish to first check if there is a way to repair the existing one

Maybe to explain the picture: the tank is a tetrahedron, so like a cone triangle and with the top down. The pre owner cut the top out, the cut out part is present.

Thank you all a lot of recommendations!

With a big enough hole in the top you could weld it - providing the exterior of the tank in the weld area can be isolated from contact with anything flammable. TIG/Heli-arc welding is lovely, if everything is perfectly clean & dry. But keep in mind the fact that you'd need to get both hands/arms in the tank; the filler rod has to be fed manually with one hand while the TIG torch is in the other. There are stainless steel wire-feed products out there, which a good welder could use one-handed in such a space. Maybe. But if it were my tank and I absolutely had to weld it, I'd look for the fancy stick rod from Nassau (or a similar company) that works well in wet locations. No matter what weld process you use, burning your boat up is a real concern if the tank is that tough to get too. S.S. has very low thermal conductivity, so the heat would stay pretty close to the weld area. But it does get VERY hot in that small area, for the same reason. Best of luck. As a life-long welder, I vote for the bladder.

[sailcrazy]

jharding...please tell us more about these products. My 30-yr old boat has 4 s/s water tanks....all under the sole and built-in furniture, and between stringers. Via the single 12" dia inspection port in each one I can see some rust spots on the inside, but (so far) no leaks. But I'm expecting it to happen sooner or later.

[S/V Adeline]

Originally Posted by jharding

There is a company called Muggy weld, check them out on youtube, they make different rods and pastes to weld(solder) stainless and aluminum with a propane torch. I fixed a stainless hot water tank that had pinhole leak, very easy and worked great. I also butt welded two pieces of aluminum together and could not break them apart, I can now fix a lot of things on my boat with a propane torch instead of hauling my tig welder.

I appreciate the input here, I believe you might have provided a solution for my leaking diesel tank!!

[rmlarson1098]

Originally Posted by sailcrazy

jharding...please tell us more about these products. My 30-yr old boat has 4 s/s water tanks....all under the sole and built-in furniture, and between stringers. Via the single 12" dia inspection port in each one I can see some rust spots on the inside, but (so far) no leaks. But I'm expecting it to happen sooner or later.

Welding electrodes ('stick rod') are made by weld supply companies such as Nassau, ESAB, and others for very special applications. One such electrode made by Nassau (and maybe others) works very well in wet locations, even in water. I know, I know, all the welders out there are saying "Bullsh*t! But I've welded small holes (3/16" dia.) overhead, in the bottom of high pressure piping systems with such rod, and it works. Water was pouring out under a lot of static pressure, and when I struck up the water just sort of danced away and in a few seconds the hole was filled. A little pad welding, a little grinding, good as new.
So. That was mild steel. Shouldn't make a LOT of difference as I see it.
Get the weld area as clean and dry as you can; a little pre-heat can't hurt so it's warm to the hand. A barbecue lighter should work.
If you can get a power brush in the tank, all the better to clean the weld area.
Angle grinder, Dremel tool, whatever. But Remember this: if it's a stainless steel tank you MUST use a stainless wire brush. Even if it's a hand brush, it must be s.s. You won't find these specialty weld rods at the local Farm Supply store. Have to go to a weld supply store. They are pretty pricey, too.

[rmlarson1098]

Originally Posted by sailcrazy

jharding...please tell us more about these products. My 30-yr old boat has 4 s/s water tanks....all under the sole and built-in furniture, and between stringers. Via the single 12" dia inspection port in each one I can see some rust spots on the inside, but (so far) no leaks. But I'm expecting it to happen sooner or later.

One other thought: if you can get a good part of the top off of the tanks, welding up the insides shouldn't be that big a deal. I'd use an angle grinder and cut-off wheel myself (hate reciprocating saws) to open the tops up but one would have to watch the sparks when cutting. Sheet metal shield or even a wool blanket from the surplus store would control grinding sparks. The inside could be welded with stick or wire feed, as the sparks created - there will be sparks - wouldn't be a problem inside. The place for heli-arc (same as TIG) would be welding the tops back on - no sparks! Or at least there shouldn't be...
The same welding machine should run stick and TIG but you'd have to get a small bottle of argon for the TIG welding, plus a TIG 'rig' or torch. DC positive for the stick welding, DC negative for the TIG. Just switch the cables (welding & ground cables) at the machine to change polarities from positive to negative.
Probably too much information! Sorry. I love to weld.

[S/V Adeline]

Originally Posted by rmlarson1098

(hate reciprocating saws)

Come on, you haven't had a good day unless a reciprocating saw pins you against a bulkhead and beats the living crap right out of you. (Fun times)

The primary reason I suggested TIG was to prevent spatter/slag inside water tank.

I realize this is the best time for thorough cleaning, just thinking of S.S. and how bad it spatters.