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Old 09-07-2012, 17:10   #46
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Re: Gel Coat Blisters Above the Water Line

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Originally Posted by delcrest View Post
found this write up , makes interesting reading
The Real Story of Osmosis Blistering
Interesting article, I've just ordered Wagner L606 moisture meter as recommended by the author and several posters on this thread.
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Old 09-07-2012, 21:45   #47
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Re: Gel Coat Blisters Above the Water Line

We followed the recommendations in that article except we also heated the hull with a Hotvac. The author states that heating the layup doesn't stop the hydrolysis but simply slows it down.

In any event, it seems to have worked really well.
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Old 09-07-2012, 22:15   #48
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Re: Gel Coat Blisters Above the Water Line

Thanks Muskoka, It's encouraging to hear that your repair was successful.
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Old 09-07-2012, 22:54   #49
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Re: Gel Coat Blisters Above the Water Line

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Originally Posted by muskoka View Post
We followed the recommendations in that article except we also heated the hull with a Hotvac. The author states that heating the layup doesn't stop the hydrolysis but simply slows it down.

In any event, it seems to have worked really well.
Our yard has been using the Hotvac for over ten years now. It is the only way to go for hull drying. It does totally stop hydrolysis-no moisture no hydrolyzing. Study the science behind it, you are not just heating the layup. It's simple and effective.
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Old 10-08-2012, 04:48   #50
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Re: Gel Coat Blisters Above the Water Line

We've just put in an offer on a FP Eleuthera, but are reconsidering continuing due to the survey report we got. And the problem being the same as you have experienced - blisters and osmosis. The hull below the waterline had been redone because of osmosis - and apparently its in good condition - but for some reason (probably the warranty) they didnt do above it. FP paid $NZ150,000 to do it only after the owner sued them. The survey report we had done commented on the blisters and bad fairing and core print on the surface of the gelcoat above the waterline. His thinks that if the hull was stripped down as the below waterline was the cost would be many times the figure above. He is pointing the finger at the epoxy not being mixed properly and not having cured properly.
The owner thinks that the blisters have finished now and it happy to have the deck drilled to check, and strongly thinks they won't get worse. Be great if that's true as we love the boat, but dont want to buy a lemon.... We're trading in the house so really cant afford a big muck up...thanks
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Old 10-08-2012, 18:37   #51
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Re: Gel Coat Blisters Above the Water Line

Yeah that's a hard call, the only thing FP will say is that it's not structural.
There appears to be a lot of boats blistering after they have been repaired but some are OK and some never have any blistering.
The problem is related to the resin FP used not the barrier coat, I'm sure FP know what it is but they won't say what it is to me.
Personally I'm not keen on doing a full peel on the topsides I just can't see the point.
What I really want to know is whether the resin below the water line is still reacting or has the water traveled up the hull and is now reacting with the resin higher up?
Either way the water has to be removed or neutralized somehow.
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Old 10-08-2012, 20:22   #52
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Re: Gel Coat Blisters Above the Water Line

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Yeah that's a hard call, the only thing FP will say is that it's not structural.
There appears to be a lot of boats blistering after they have been repaired but some are OK and some never have any blistering.
The problem is related to the resin FP used not the barrier coat, I'm sure FP know what it is but they won't say what it is to me.
Personally I'm not keen on doing a full peel on the topsides I just can't see the point.
What I really want to know is whether the resin below the water line is still reacting or has the water traveled up the hull and is now reacting with the resin higher up?
Either way the water has to be removed or neutralized somehow.


What does the moisture meter tell you? Are there high readings on the area of hull in question? That would tell you what's happening fairly accurately. The Wagner L606 is for housing contractors and house painters, not sure it even has an FRP scale. You want the JR Overseas GRP 33.
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Old 10-08-2012, 21:45   #53
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Re: Gel Coat Blisters Above the Water Line

LydiaS,

"The owner thinks the blisters have finished now...."

I'd walk away. There are plenty of boats out there so why buy one with problems? A full topside peel is a nightmare job.
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Old 11-08-2012, 18:18   #54
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Re: Gel Coat Blisters Above the Water Line

Sorry correction above - FP offered to correct in a certain way and the owner wanted a more intensive process done and threatened to sue, so the suing didnt actually happen as FP fixed the bottom.
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Old 11-08-2012, 18:28   #55
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There are thousands of boars with blisters. How many sink because of them? Fix the large blisters and keep on sailing...
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Old 11-08-2012, 19:14   #56
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Re: Gel Coat Blisters Above the Water Line

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Sorry correction above - FP offered to correct in a certain way and the owner wanted a more intensive process done and threatened to sue, so the suing didnt actually happen as FP fixed the bottom.
That's really academic, the repair hasn't fixed the problem.
Is the boat cheap?
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Old 18-09-2012, 16:44   #57
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Re: Gel Coat Blisters Above the Water Line

Has anybody heard about a pending law suit between FP and their resin supplier?
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Old 19-09-2012, 00:51   #58
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Re: Gel Coat Blisters Above the Water Line

Hi D Lady,

Nether heard about conflict and pending law here in France...
anyway all manufacturers have trouble with osmosis...
but in my opinion it's really far away from big structural trouble ( like Dean cat for example ).
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Old 19-09-2012, 15:32   #59
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Re: Gel Coat Blisters Above the Water Line

Thanks Oliver,

Yes you are right, in fact all GRP boats have osmosis it is impossible to stop.
It just comes down to how quickly the hydrolysis reaction occurs, good boats are a few hundred years while others a few years or even months.
How is your Lipari going?
Every time I go through my Lavezzi's doorway now, I think how nice it would be to have one like the Lipari.
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Old 19-09-2012, 16:19   #60
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Re: Gel Coat Blisters Above the Water Line

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Thanks Oliver,

Yes you are right, in fact all GRP boats have osmosis it is impossible to stop.
It just comes down to how quickly the hydrolysis reaction occurs, good boats are a few hundred years while others a few years or even months.
How is your Lipari going?
Every time I go through my Lavezzi's doorway now, I think how nice it would be to have one like the Lipari.

That statement's a bit strong, all GRP boats certainly do not have osmosis and it is definitely not impossible to stop. Modern construction techniques and materials have almost completely eliminated osmosis problems for most manufacterers. It's not a problem for most boats built in the last ten years, except for certain manufacterers. Most builders are using vacuum bagging, infusion, vinylester resin and/or gelcoat, or some combination thereof to prevent osmosis. Epoxy laminates are more common as well, though still high end. And many manufacterers barrier coat or at least offer the option during the commissioning phase as well. We started barrier coating bottoms as part of the commissioning process for new boats for several builders during the '90's and have ever since. Many modern boats that have been coated since new will read shockingly dry on the meter when tested properly, with no signs of osmosis at all. This is hardly a universal problem.
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