I installed a RTM 44 liter sausage shaped water bladder under the longitudinal cockpit seat in my Clubman 8. Disabled the bow tank as I didn't like the weight distribution. I had to drill the deck behind the chain plate and then down through four layers of a shelving unit and multiple other cuts to facilitate the filling pipe plus fit some restraining timbers and an adjacent water pump...

Quite a lot of work has gone into the exercise but the damn thing leaked as I found out in the Whitsundays. I exchanged it and fitted another one last week I only to find out that it too leaks. Earlier this week I exchanged it for third unit which also leaks. After removing the protective plastic cover/sheath it appears that the leak is coming from a welded seam and in particular where the longitudinal seam meets the transverse seam at one end of the bladder.

It is a low profile bladder and I can't find anything else with appropriate dimensions or takeoffs at the ends rather than in the middle.

Obviously the product has inadequate welding and I am unlikely to get a good one.

Is anyone aware of some Silastic type product which is flexible enough for use with a bladder which must go from collapsed and empty to a fairly taught stretched state when full and which adheres to flexible plastic plus has some strength? I don't think my usual 291 go to is up to the job. The repair does not have to be aesthetic and I don't mind using bloody great dobs of the stuff as long as it hangs on. Need a quick fix so I can go to Moreton island early next week.

You'd also require the goop to be food safe, i.e. non toxic.
WW sells bladders up to 100 litres, which might mean that you have excess capacity in the bladder compared to the under-sole compartment.
Or you could seal the leaking areas with by heat sealing them: perhaps using an iron with some sort of teflon heat shielding tape?

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FabulousPhill said..
You'd also require the goop to be food safe, i.e. non toxic.
WW sells bladders up to 100 litres, which might mean that you have excess capacity in the bladder compared to the under-sole compartment.
Or you could seal the leaking areas with by heat sealing them: perhaps using an iron with some sort of teflon heat shielding tape?

Thanks Phil but I'm a bit reluctant to put an iron on it in case I make a hole somewhere else. 100 litre bladder would be too big and would just fill up the area with plastic I fear-it's quite shallow. I'm not too worried about food safe as the fix will be on the outside and only say a pinhole exposed to the inside plus I don't really plan to drink the water anyway as I normally take a few of those 10 l casks for drinking water.

You hear people say that certain products sticked like sh.t to a blanket and I guess I'm after something like that which is also flexible. Probably something that chemically bites into the plastic of the bladder although I'm not aware of exactly what the bladder is constructed from. Don't fancy sanding the bladder to improve the bite.

A hot melt glue gun?
www.bunnings.com.au/boyle-hot-melt-glue-gun-pack_p0322564

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FabulousPhill said..
A hot melt glue gun?
www.bunnings.com.au/boyle-hot-melt-glue-gun-pack_p0322564

Yes thanks that might work I don't have much experience with that stuff and I'm thinking perhaps something flexible might be better. The problem with a glue gun is I probably only get one shot at it.
In the end I'll probably try anything. I'm just a little disappointed in stuff like 291 which seems to stick like crazy before it goes off but then seems to be quite easy to peel off afterwards (except of course on the car upholstery where I unknowingly sat down with some of my bum) even if I give it a coat of acetone before starting.

Hi Jules,

Are you not better to buy a better brand? I recently bought a Plastimo bladder for the Magnum and have had no problems with it. I replaced a Plastimo bladder that had been in the boat for many many years by the looks of it before it finally let go with an abrasion hole where the plastic had hardened and rubbed on a pressure point.

You can also buy a bag sealer online for sweet FA and reseal the bladder yourself. Another option is to use a normal ironing iron, using an HB pencil to create the weld point, and cover the bladder on both sides with greaseproof paper. I have used this method with kite bladders which are thinner, but just apply more heat. If it's buggered already, you have nothing to lose.

DM

It's a pity it hasn't worked when you've made such a tidy job of it!

I have to replace the one in my boat, what is the go-to brand? Is it plastimo?

I can't pretend to be enthusiastic about all the plumbing involved.

Repair that corner and what happens to another corner down the road?
Time to bail out and get another better bladder.

gary

My currentb Plastimo bladder has suffered from weak threads in the inlet and outlet so it may not be an upgrade. The one I had eons ago was 100%.

Your tub looks really clean, can you get rid of the bladder altogether? I had 200l a side without bladders, never once had a leak. Had flush mount big inspection hatches that screwed into the top panels so access was awesome..

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shaggybaxter said..
Your tub looks really clean, can you get rid of the bladder altogether? I had 200l a side without bladders, never once had a leak. Had flush mount big inspection hatches that screwed into the top panels so access was awesome..

Thanks; that thought has definitely crossed my mind :). What material would you use for the top? Ply with a couple of coats of epoxy painted on? Those inspection hatches always leak however in my experience.

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garymalmgren said..
Repair that corner and what happens to another corner down the road?
Time to bail out and get another better bladder.

gary

True but it's an odd small size and I can't find any other brand.

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julesmoto said..

shaggybaxter said..
Your tub looks really clean, can you get rid of the bladder altogether? I had 200l a side without bladders, never once had a leak. Had flush mount big inspection hatches that screwed into the top panels so access was awesome..

Thanks; that thought has definitely crossed my mind :). What material would you use for the top? Ply with a couple of coats of epoxy painted on? Those inspection hatches always leak however in my experience

The top of the watertank was foam cored fibreglass with solid fibreglass inspection hatches. Each inspection hatch had a simple o-ring in a 5mm rebate in the hatch and screwed down.
My top plate was part of the structure so I was going to say glass or silicon it in , but your area looks a lot smaller and so clean, maybe you could just rebate an o-ring in the top plate without inspection hatches and be done with it?
Something like this with inspection hatches, or even simpler, just make a top plate?

Time to Chinese non-marine.
Gary
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Considering water is the number one thing for yours and more importantly your childrens health I am amazed that your prepared to drink out of utter garbage, considering that even the so called food safe plastics are now being proved to contain for ever chemicals then again some people are drinking tap water.
rumble.com/v5gl425-epa-loses-historic-fluoride-case.html?e9s=src_v1_mfp

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garymalmgren said..
Time to Chinese non-marine.
Gary
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Too big and wrong shape unfortunately. However I'm all for non Chinese and not supporting the heavy industry of a militant, bullying, expansionist dictatorship wherever possible.

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MAGNESIUM said..
Considering water is the number one thing for yours and more importantly your childrens health I am amazed that your prepared to drink out of utter garbage, considering that even the so called food safe plastics are now being proved to contain for ever chemicals then again some people are drinking tap water.
rumble.com/v5gl425-epa-loses-historic-fluoride-case.html?e9s=src_v1_mfp

Thanks and very true but as I mentioned above I take cardboard casks of water from Woolies/Coles for drinking and coffee. The water in this tank is just for washing up etc. I do the same in my larger yacht.

Update- bladder packaging says food grade PVC on the pack but as it's made in China I don't know whether I trust that.
Most adhesives in Bunnings that I spent 40 minutes looking at this morning (even the ones that say they work on plastic) say they don't work on polyethylene or polypropylene but if you independently look up whether super glue or other glues work on PVC they say not really unless you sand and then still not well. I think however that is hard PVC which might be different to flexible. I know when I was adding my additional giant PVC pipe cockpit drains out the back through the lazarette and tabbing them in I read that epoxy doesn't stick to hard PVC unless you quickly flame the area (I did that and also roughed it up no end).

As for welding - those kids craft toys made from hollow fusable beads are mostly low density polyethylene and zip ties are apparently mostly nylon so think that sandwiching/melting those dissimilar plastics between the pvc layers may not work.

I think I'll try PVC pipe joining primer and then cement. We all know that that softens and chemically affects hard PVC although I don't want to put too much on and melt the bladder.

I'm with shaggy. As for the lid I'd just epoxy some surfboard mat to the inside of a ply lid & stick it with fixtec or even fixtec some polycarbonate or acrylic, and if access is need in the future cut a hole in it then. I have found a bit of Vaseline on the o ring & threads of the " dinghy inspections " makes em work

I have had epoxy glassed ply water tanks in my 24 year old cat. Never had an issue. Preglass the ply on its bottom before you epoxy it down onto the surrounds with silica glue mix - fill in the sheathing cloth (surfboard) glass weave with extra resin to consolidate the surface gloss, only use epoxy resin - don't bother about painting. Sand only the very edges for gluing. I had an issue with a centrboard case leak and needed to go through the stb tank. I put two Nairn hatches in the top. Doesn't leak but my cat doesn't lean over. How about you don't put the hatches in until you need to - and why do you need to? My port tank has never been cleaned or opened or anything, no hatches in it. We are all still here and healthy.