I've seen special machines that shave off a whole layer of glass from the hull. Then the hull is dried and re-glassed, faired and painted. The guys in the yard (Lauries Qld) where I get my boat done were doing this under warranty on some Fontanes that weren't manufactured correctly. "Bring Out Another Ten (thousand)

What next?
Easy, scrape the paint off and determine what it is. It looks more like paint bubbling than osmosis although there may be some of that as well. First thing to remember is that boats don't sink because of osmosis.

If it is paint bubbling it could be that there is incompatibility between paint types, in which case you may need to get back to gel coat and start again.
If it is osmosis, pop a blister and have a good smell of the fluid inside, if it smells of acetic acid treat by drying and grinding with a die grinder and filling with epoxy putty. Drying out can take many months and should be assisted by any means available to you.

Most boat yards will try and instil the fear of god into you hoping to be able to milk you for thousands of dollars, just remember no boat has sunk because of osmosis.

I agree with LC, some of those bubbles look too big to be osmosis. It's going to be a pain whatever
the cause. I hope it's paint rather than osmosis but as LC said, no boat has sunk because of osmosis.

Mine had heaps of little bubbles when I purchased it.
had it blasted back to gell coat and all the old bodgey repairs ground out filled properly and recoated. I was going to walk away from the boat when it was found in the prepurchase inspection but after talking to people in the industry who had no vested interest in my purchasing the boat all assured me it was not the big issue it use to be as long as it's not structural. Repair it and keep an eye on it and repair any other that show up in the future.

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LooseChange said..
What next?
Easy, scrape the paint off and determine what it is. It looks more like paint bubbling than osmosis although there may be some of that as well. First thing to remember is that boats don't sink because of osmosis.

If it is paint bubbling it could be that there is incompatibility between paint types, in which case you may need to get back to gel coat and start again.
If it is osmosis, pop a blister and have a good smell of the fluid inside, if it smells of acetic acid treat by drying and grinding with a die grinder and filling with epoxy putty. Drying out can take many months and should be assisted by any means available to you.

Most boat yards will try and instil the fear of god into you hoping to be able to milk you for thousands of dollars, just remember no boat has sunk because of osmosis.

LC's comments are the best calm common sense advice I have yet seen posted about the supposedly dreaded Osmosis and the boat yards doing the repairs. His last line sums it up completely.

Once you have smelt it you will not forget the sour smell of the liquid in the blisters, repair it as it appears at each haulout.

Mike

Thanks for the feed back
When i first pull here out it did not look all that bad. So i spent the time and mony and scraped here back to gelcoat the boat yard put a couple of layers of under coat and then the anti foul.
It after the work was jus5 about complete that the blisters were very noticeable and it was very dishartening.
The advice and comments have made me feel a lot better thanks.

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benateau281 said..
Thanks for the feed back
When i first pull here out it did not look all that bad. So i spent the time and mony and scraped here back to gelcoat the boat yard put a couple of layers of under coat and then the anti foul.
It after the work was jus5 about complete that the blisters were very noticeable and it was very dishartening.
The advice and comments have made me feel a lot better thanks.

To me it looks like the antifoul was painted over a moist surface. As the temperature got up a bit the water expanded. If it's still out of the water try a pin prick.

I second doing one of them to see if it's really osmosis, if it is just do a bit each haul out and go sailing. Keep an eye on them and do the worst ones each year, they may just sit there and not get bigger. Think of it like a game at haul out, have a few dollars set aside at haul out, when it comes out of the water and is cleaned have a look, no worse go to pub and celebrate with your money, worse put the work clothes on and start grinding , then go to pub cause its not as bad as you thought.

B281- As an ex-boatbuilder, all I can see is a ****ty afternoon of grinding, it's no big deal. It's only in older yachts like some of the C&Cs which were balsa cored below the waterline where you we would start sweating.

To me it looks like the tie layer between the gel coat and the laminate could be letting go, often seen when vyinalester laminates are laid over polyester gel coats and tie layers.

When I put mine on the hard it had a few bubbles ( blisters ) but they turn out to be under the anti foul not under the gel coat there were a few I could count on one hand .
Yours to me looks like above the gel coat and between the anti foul . Meaning not quiet prepped right moisture of not enough sanding perhaps
Hope it turns out like that for you
If its osmosis you will smell it once you lance it

I have just put here back in the water so i will start saving. I have photos now so i can see if they get any bigger and next haul out as suggested i will be a prick and see what weeps out.
sounds like a plan to attack a few at a time every haul out. Haul out wont be for another 12 months.
good news is that the boat yard didnot make a big song and dance about it.

Again thanks for the advice and rational carm coments

Mick

I had to consider the implications of osmosis when I purchased Mojombo. She had a fair covering of blisters and the Surveyor popped one to confirm. Yours look a bit bigger than the worst on Mojombo but you have less.

After looking into the implications and taking advice from Pat, I came to a couple of conclusions and possible ways to tackle them.

Firstly, as long as they have a good solid foundation underneath and the moisture has not softened the glass below, they are not a "major" issue. Like posted above, some ppl don't understand the implications and would walk away from the deal.

Firstly, short term, they will continue to get bigger if they remain "unpopped". It seems counter intuitive to open them up but by the nature of osmosis (the chemical/physical action of a higher density liquid pulling fluid through a semipermeable membrane in effort to equalise the density), they will gain more pressure and affect the underlying structure more if the liquid remains below the surface and continues to suck more water into it. If salt water/fresh water is allowed to flow into the bubble, it will cease to be under pressure and do less damage below the surface.

Two dogs has tackled it head on - all in one go. I was recommended about $10k Materials an labour to get it done professionally on the mainland (42' boat) or 5 grand in materials alone. grind it - dry it out (heat and acetic acid potentially) and patch it.

What did it cost you Dogs?

The other way is to hit each bubble individually like OLD BOY RACER said - on each haul depending on their size. May end up a lot patchier that way.

Be aware that when you prick it, it probably wont weep out but spray out, wear glasses.

I had a lot of other work done at the same time some covered by insurance all up including what insurance paid for was about $35000. But it was about $5000 for the blasting and treatment.

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benateau281 said..
Thanks for the feed back
When i first pull here out it did not look all that bad. So i spent the time and mony and scraped here back to gelcoat the boat yard put a couple of layers of under coat and then the anti foul.
It after the work was jus5 about complete that the blisters were very noticeable and it was very dishartening.
The advice and comments have made me feel a lot better thanks.

Hi b281, In your post, which I have highlighted, did the boatyard do the undercoat and antifoul?
If, as has been suggested above that the problem could be a fault between paint layers, and the yard did the work, then its not your problem, the boatyard owns it...