Plastic Water Tank Cracked! How do I fix it?

[mikebikeboy]

Replumbing the boat today with new pipes, noticed a 3 inch crack in the side of the water tank, which is made out of white plastic. Anyone know the right way to fix this?

I don't know if it leaks---I have never filled the tank. But I'd rather fix it so it doesn't spring a leak when I'm cruising.

[Jammer]

The way you fix it is you remove it and replace it with a new one, or two new ones, and the way the world works the capacity will be somewhat less because you won't be able to find one that quite fits the space.


The reason you do that is that your 40 year old water tank with a crack in it is made out of plastic that is now brittle and no longer flexible. Sure, you can try to patch it with G/flex, or try your hand at some plastic welding. Might work, but the experience of others who have taken that road is that the materials and equipment cost is high and the odds of success low.

[Lepke]

If you decide to fix the crack, drill a hole at each end of the crack. It relieves the stress that caused the crack. Grind out the crack to about 45° on each side so your patching material has more area to bond to.

[Orion Jim]

The Cape Dory Board • View topic - Polyethelene tank repair
Two methods of repair discussed here….

[tkeithlu]

Lepke speaks with wisdom. The crack is not necessarily the end of the tank, although it certainly could be. So, and assuming that you are not about to take off on a water-critical circumnavigation, you stop-drill the crack so it stops propagating, bevel, and glue. That's the simplist repair that is likely to work. In the process you'll find whether the plastic is brittle. Save drastic solutions (replacement, often a whole bunch of trouble) for when it is obvious that you need them.

[zstine]

I'm guessing it is low density polyethylene, as most white plastic tanks are. Not many glues or epoxy will stick to it, BUT it is relatively easy to 'plastic weld' if you have access. There are a lot of youtube videos on it. I have found a micro torch and PE plastic tubing, pre-flatenned, to be a good combo for heat and fill. Electric irons don't work and heat guns (ok for pre-heating) don't have the precision. You could try pre-heating then a hot glue gun to fill the crack as well, but its not as good... Practice on an old cutting board before you attempt repair.

[arcticmonkey]

there's repairs and then there are "repairs"... me thinks this falls into replace (repair).... wee bit of research will determine your best course of action

[bailsout]

That boat is about the same size as mine. I removed my water tank and replaced it with gallon water bottles. Good moveable ballast! And they all can’t leak or get contaminated. I just use fresh water for solar shower bag, drinking, cooking and brushing my teeth.YMMV.

[bailsout]

It also opened up some storage space and easy inspection/access to my chain plates for the mizzen mast. Removed and sealed deck filler fittings.

[gonesail]

replace the tank. once they start cracking they are brittle and it only gets worse.

[jen1722terry]

Coincidentally, Practical Sailor had an article on repairing plastic water tanks some years ago. Sadly, the issue is at our other home in New Hampshire and we're now in Maine. You should be able to call them and ask for the back issue or maybe they'll just email the article for a small fee.

Tricky to repair, those polyethelene tanks. You need special glues. Also if the repair is low in the tank, may be better to replace it.

Good Luck

[LeeV]

We had that happen on one of our trimarans. We cut it, dried and smoothed it out and then inserted a flexible bladder using the old tank to hold it and brought the new neck/filler up to the same spot.

[mikebikeboy]

Wow thanks everyone. I think I'll try the gFlex + fiberglass

If that fails it fails. If it works then yay.

[chasfgr]

Originally Posted by mikebikeboy

Replumbing the boat today with new pipes, noticed a 3 inch crack in the side of the water tank, which is made out of white plastic. Anyone know the right way to fix this?

I don't know if it leaks---I have never filled the tank. But I'd rather fix it so it doesn't spring a leak when I'm cruising.

Almost impossible to make a successful long-term repair.
If it's near the top of the tank, a temprary repair with adhesive tape can work.
Yje melancholy fact is that you'll probably be better off replacing it sooner than later.
I'd check and see if it actaully leaks - sometimes they don't, until in a seaway.

[Hudson Force]

I was finally resigned to using LeeV's plan of placing a bladder inside my old white plastic water tank. I spent a couple of years trying to seal a crack at the top fill connection that would leak with a heel when the tank was full. I was limited with access and never made a good seal with my attempted repairs. I lost some volume with using the bladder tank, but removing and replacing the tanks would have required taking out my generator, refrigeration and more just to gain room for the refit.