Failing Aft Water Tank H46

[burtpreston]

It was the tank under the starboard settee. I don't  recall the location.
Burt Preston

[etuman]

Brilliant Burt!  Which tank and approximately where were the leaks found?

Eric
88 44 Charleston Harbor

[burtpreston]

We had a leak in one water tank and after pulling the tank and having it welded we ended up having two leaks!
To solve the problem, I plugged all holes in the tank (vent, inlet, etc.) connected a dingy air pump, and slightly pressurized the tank. With soapy water I checked the tank for leaks and marked them. Then, after cleaning the area around the leaks, I pulled a vacuum on the tank with the air pump while I applied epoxy to the leak areas. The vacuum pulled the epoxy into the tiny holes. I also applied heat to the area to thin the epoxy and later help set it. When the epoxy was pulled into the hole, more was applied I kept doing this until the hole was plugged with epoxy. Twelve years later and no leaks.
Burt Preston
H44 -83
Exuberant

[Moonlight]

Our aft water tank had a slow leak in the corner.  I was able to reach the corner through the access port so I cleaned the corner as best as I could with fine grit sand paper and put a coating of JB weld on it.  That was several years ago and it's still holding. 

Jack
H49#31
Moonlight

[Ambition]

After a discussion with the super helpful folks at Hylas / Queen Long, I have opted to cut 3 additional access holes in the top of the tank and reseal all welds with an appropriate epoxy (yet to be sourced). Will need to make  SS covers and backing plates for the 3 new holes in the tank.
Plan B will be to lift the tank out of its current position and then from the outside, TIG weld SS patches over all seams. This will avoid ant excessive heat build up against the supporting wood.

Thanks all for the input suggestions!

Merrill
S/V Ambition H46#40

[jt11791]

Leakey welds are common and catastrophic failure is rate.  Many leaks go unnoticed or ignored for years.  Can you access the leak from inside the tank via the inspection port?  Plugging it from the outside maybe possible, though the fix maybe temporary.   I would try a lot of different repairs before I gave up on the original tank.

[Knoxan]

Merrill I was fortunate having a specialist tank manufacturer nearby and was not contrained by time having a whole winter to fix it.

The interior has several baffles welded to the side walls and in my case the top. See photo. I suspect the top with baffles attached was then welded to the sides and the bottom added last. If that is the case with yours removal of the top in one piece may prove difficult. I removed mine piecemeal.
Inspection through the port may shed light on that.

Best of luck.

Regards
Andy

[Ambition]

Andy, thank you for the very detailed response. I have just 2 months before launch and the boat is in the Caribbean. Since you have been deeply involved in that tank, I have one question to ask you. Step 1. cut the top of the tank off to gain access to the full interior. 2. Weld new angle bent SS sheet (5 or 10 cm each side the 90 degree bends) to the interior to cover all existing welded areas as a patch. 3. weld the tank top back on.

Thanks again
Merrill

[Knoxan]

Further to my last post, drawing attached showing the complex shape of the two replacement tanks which sit side by side and were a tight fit.  I appreciate each boat may vary slightly so the dimensions should be checked to ensure accuracy if replacement is considered. The existing steel tank base with a short upstanding side was left to give a flat base and lateral stability. If sides had been removed completely there would have been a bit of leeway in fitting.
Andy

[Knoxan]

I had the same problem a few years ago and posted as follows:

"I suspect that Hylas welded the tanks with inferior welding rods. A common failure when welding SS is concerned. My water tank under the master cabin berth weeped so badly that I had to replace it a couple of winters ago with two custom tanks fabriated from Food Grade HDPE by TekTanks in the UK.
The first problem was that the original tank was too big to remove in one piece. Spent several days cutting it up in situ. I did leave the base and the side walls cut down to form a frame for the new tanks. The new tanks were sized to fill the frame and were a tight sliding fit through the aft skylight. Capacity is slightly less but not significant. Outlets from the tanks are valved and manifolded under cabin floor access hatch. They are both filled from the original single deck filler although only one is connected to the watermaker.  I thought this would be good in case the watermaker failed and tainted all the water. The Tank Tender is installed in the one I use last.
The remaining water tank forward starboard side is 40USG I think weeps slightly, always damp around there. I might try the JP Weld fix."

Andy
H46#32 True Brew

[Ambition]

I was just notified by the technician that our aft water tank is leaking. Unfortunately, the welds have started to corrode and leak and there is a concern that it will not hold up under usage and with water sloshing in a seaway. The original thought / plan was to get the external and internal areas to be able to patch them. That has turned out not to be feasible as accessing the areas behind the baffles is impossible. One suggestion from the yard is to cut the tank to get it our and then build a new tank in fibreglass - less costly than trying to build a new tank in SS and then welding it in place. 
I am curious to know if any other 46 owners have come across this issue and what they found as a viable solution.

Thanks in advance for you input,
Merrill
S/V Ambition  H46 #40