How to live with osmosis?

iandwall

iandwall

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My boat has osmosis - at some point in the past it's been painted with an epoxy paint, but there are many blisters through that now. I don't want to spend loads of time and money drying out and treating, I just want to use the boat. I'm sure it won't sink.

To that end, I've removed the old antifoul, sanded down the old epoxy (to the gel coat in some areas), and treated some of the worst blisters.

Now I'd like to rapidly prime and antifoul again - in this cold weather. Using something like vctar2 seems a bit pointless as it will seal in the existing moisture, but it would fill in small imperfections (I believe), plus it might not go off in this weather. Primocon would be easy but won't fill in all the little bits I've missed.

Any suggestions for a solution that will get me back in the water quickly, and let me deal with it piecemeal in future?

Thanks
 
Living with osmosis

The bit that concerns me is "the bits I've missed". What did you use on the areas you've treated?
It is important to avoid any solvents getting into the laminate when you treat blisters as it will promote new blisters in the future. If you grind blisters out you should wash them very thoroughly with fresh water and then dry completely. When dry fill with solvent free epoxy filler. If that's what you've done then you can finish with a solvent based epoxy that will waterproof the area effectively. If you;ve "missed bits" with the filler it would be better to get that right first before thinking about what to coat with. Assuming you haven't really missed bits then I would coat the treated areas with at least 3 coats of solvent based epoxy as that will cure (slowly) at the temperatures we are starting to get now. Personally wouldn't use Primocon as it's far less durable and waterproof than epoxy.
 
Im no expert, but you seem really keen to get it back in the water. When did you intend to address the issue? if next season or not too much further down the line then I would do nothing now - just primer and antifoul. Then in the future get professional osmosis treatment.

I have seen a few people around boatyards over the years, they have bought a boat at a bargain price with osmosis, they then spend ages grinding out blisters, filling, hundreds of pounds worth of epoxy. It all looks nice and smooth out the water. They launch it, then the following winter it looks like a lunar landscape and they wonder why!

unless its very isolated the only cure is proper treatment. anything else will make it worse and waste time and money. so either do nothing or go for the works. Im sure it wont sink in the meantime!
 
Some Interesting Information On Polyester Resin Hydrolysis

The question is what is a proper treatment and can you live with what you have? Read this thread: -

http://www.ybw.com/forums/showthread.php?t=228835

and go to Post No 9 and down load the book from the link. I have an old boat and have done my own research on the web and come to a conclusion based on my amateur understanding. I don't know how factual the comments made in this book are but I am not dismissive of the findings.

I think the book is as good a place as any to start to make your own mind up about what to do.
 
Thanks everyone for the responses..

Having read the the referenced thread and book (or the relevant bits anyway), I think my best option for now is indeed to just prime (non-epoxy) and antifoul.

More serious efforts can wait for another day (and more funds). Or perhaps she will sink in the mean time.
 
This is a message to a query of mine to '0ldsaltoz' a fibreglass expert on here. I wanted the chemical i used in past to remove the acidic fluid in blisters.
Good advice re treatment piecemeal, hope it helps.

G'day Mike,

I suspect the fluid you mention was Acetone, very good for removing contamination on the surface of most things but will melt some plastics.

If when sanding the surface of a blister you see any discolouration, that is, it's not just local water trapped under the paint. You MUST remove the discoloured material, this is contaminated and no amount of resin will fix the problem, but rather seal it in and encourage it to continue to grow.

If the blisters are very small, a dremell is good or even an angle grinder, one ground the area should have no discolouration and no white dry looking cloth that has little or resin in it.

The area should be hosed clean and left to dry, an inspection the day will indicate if you need to go any further, look for new stains, grind them again and wash and check again later for more staining.

Only areas with no staining should be washed clean with Acetone and an epoxy applied.

Deeper areas will need re glassing with an epoxy resin and cloth, small areas should be filled with a mix of epoxy resin and closed cell balloons.

Hope this helps......
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