Wet Bladder Repair - magic sticky stuff?

[MangoCats]

O.K. - I know this isn't a super serious situation, I can always just install a new bladder without too much trouble, but...

I have 100 liter bladders installed under the port and starboard settees, not super easy to access, but easy enough. The port side bladder vinyl looks to be in good shape, but its seam stitching is weeping. When full, maybe 10 liters a day drains to the bilge, as the bladders get emptier the leak slows to a crawl when maybe 20 liters remains. Previous owner (or maybe the bladder mfgr) put a thin bead of some kind of goo on the seam, but it clearly didn't hold well.

I was thinking I might apply a bigger patch along the seam, maybe 4" wide along the length of it, but the problem is: I can't (easily) get the outside of the bladder dry because even with the system drained as far as the house pumps will take it, there's still a non-trivial amount of water coming out of the seam when I wrestle it up where I can work on it. The first patch material I tried to apply just didn't adhere at all when wet.

Does anyone know of a (at least semi) reliable, wet apply-able flexible vinyl patching system?

[JPA Cate]

In our previous boat, we replaced the leaking bladders with s/s tanks that were specially fabricated to fit under the settees, where the bladders had been. For us, it was a good deal, and when we sold the boat some 13 yrs. later, the tanks were still in use, and trouble free.

Our misfortune with the plastic "tedlar" bladders was that, guaranteed for 5 years, one failed in 2.5 weeks, and the other, in 3 weeks. WM made it good with refunds, which we applied to the tanks. Those bladders with the guarantees were replacement for the original hypalon Vetus bladders, which had glued seams. The replacement bladders did have seam leaks, but I don't remember whether they were welded or glued. I am surprised at your mention of "stitching". There was no thread involved in any of our bladders' seams.

I hope you find something that will work for you.

Ann

[MangoCats]

This looks very much like the bladder that's giving me the trouble. It was weeping very slowly when I bought the boat (just over a year ago now), but, since I've poked and prodded and peeled back the leaking patch bead it's leaking a bit faster now. It seems that they used some kind of fiber based stitching to hold the panels together with heavy "thread" about 1/8" in diameter, and, of course, that's where the water seeps out.

Unfortunately, the compartments the bladders are in only have access panels, they don't fully open, so if not using flexible bladders the structural fiberglass under the settee cushion would need to be cut - and of course the bottom of the compartment is curved so it would be a bit of a challenge to fit a custom hard sided tank.

[GordMay]

You might search divers' ’dry suit repair’.

Nauta tanks use an extremely rugged 840-denier nylon fabric, coated on both sides with a neoprene/nitrile compound. Heavily lapped seams are inside-reinforced with a “doubler” to provide extra strength.
All Nauta tanks are vulcanized to assure leak-proof panels and seams for years of trouble-free service.
Nauta flexible water tanks use an exclusive Tedlar* inside lining to maintain a taste-free system.
➥ https://www.imtra.com/other-products-nauta-tanks.htm

* DuPont™ Tedlar® is a PolyVinylFluoride (PVF) protective film.

[JPA Cate]

We really do have to find you some glue, or you have to buy a new bladder. It will be difficult to install one properly, without access to under the settee. You need something to tie it to, and some indoor/outdoor carpeting for it to lie against so you don't get hull chafe on the new tank (or the repaired one, IF it can be repaired.)

A very long time ago, we used 3M 5200 to bond hypalon to pvc ("Herculite"). It had to be done dry, and it had to sit for about a week in a dry environment. The bond lasted for years, though. It was a repair to a soft dinghy bottom, and spent plenty of time in the water.

In the OP's shoes I'd be looking for a glue that can be used under water, and also stay flexible. Maybe that's why Gord suggested the dry suit repair strategy.

Ann

[MangoCats]

Originally Posted by GordMay

You might search divers' ’dry suit repair’.

Nauta tanks use an extremely rugged 840-denier nylon fabric, coated on both sides with a neoprene/nitrile compound.

Thanks, what

I've found so far

on dry suit repair also emphasizes surface prep, doesn't seem like it would be wet surface friendly either. Small consolation, the outer surface of the bladder is a smooth material, not a nylon that needs to be soaked through like in the linked video.

I suspect if I get it dry, adhering with 5200 or a vinyl cement should be successful at stopping or at the very least drastically slowing the leak. The bladder is bolted in at the top corners, the bottom ones are free but usually quite stable due to the weight of the water in the bladder - the leaking seam (that I know about) is along that bottom edge.

The problem is the time required to drain the bladder completely, then let it dry, then apply the patch and let it dry - while we really just want to use the boat and don't need more than 40 liters of water onboard anyway (just daysailing...) Sealing the leaking port light frame, with nice quick butyl tape, seems like a more attractive project at the moment.

Edit: Update...

O.K. - Here we go, some people at least claim that this will stick to rubber when wet, and the dimensions are perfect - going to give this one a quick try.

[JPA Cate]

Looks like it's worth a try, looks like neat stuff if it works as advertised.

Ann