Freezing of water in the hull laminate
Bill,
I put a transducer (more like a golf club than a hockey puck) in the stem a while ago, and that may confirm your observation on hull thickness. BUT
Believe I found the stem on A338 just "turned the corner" and wasn't any thicker then the hull. However after recovering from disbelief, I really beefed up the length of the stem with many turns of tabbing, Xmatt and hairy filler.
And now I wish I had laminated extra fabric onto the OUTSIDE of the whole keel/ballast keel/bilge area as I assume you did before the barrier coat process.
Drilled a number of holes into the encapsulated ballast void for discovery and for draining water and filling with epoxy. Even down here the hull was no thicker than 5/16", maybe 3/8", on the sides. My first drain holes (from the Manual) were straight up through the bottom of the keel where there was considerable thickness (one inch maybe?) But any glass LAYERING was rather abrupt, because side drain holes low down were thru much thinner hull.
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This has been a discussion of discovery. An important revelation we've all been involved in. Fantastic.
I'm unaware freezing stress IN THE HULL LAMINATE has been mentioned as a cause of gelcoat crazing by the mavens of info that abound the internet.
This observation may be unique. It's not mentioned in any list of gelcoat crazing causes. It's important because it may signal compromised fiberglass.
Bill has identified an important issue for owners of older fiberglass boats.
It seems laminate freezing would be especially important problem for our not very beefy hulls. I think we're talking about plastic within the laminate cracking into small pieces by freezing. Or worse. If bilge water weeps through the hull in crazed gecoat areas then this HAS to be a conclusion!
Here the Forum really informed to perfection!
{be nice if ebb wasn't so damn long winded.:o}
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Interesting new development...
I decided to see how far up the crazed gelcoat went. I started sanding a path up from the keel and the crazing goes all the way up to the top of the barrier coat and then stops dead in it's tracks at the waterline stripe. At first I thought it was maybe associated with the dark color of the bottom paint but that cannot be it since the black waterline stripe does not have any problem under it.
So what in a barrier coat would cause the crazing?????
I tend to agree with you...
This is what I know so far.
First the only place I had a blister problem was in the area where the gel coat had been destroyed by previous bottom jobs. And the blisters were not in the gelcoat because there was no gelcoat for them to be in. They were in the barrier coat when I sanded through that they were gone.
I believe they were caused by the trapped water in the foam inside the keel.
From what I have read fiberglass is more like wood then I previously realized. It takes on water and gives it off just like wood over it's entire lifetime. Does not matter how many coats of finish you put on wood it will still take on and give off moisture on a regular basis.
With fiberglass it is not good to seal both sides of the material and trap whatever water that is currently in it there. That can cause blisters.
So....
This is the direction I'm leaning towards in dealing with my situation.
First in the area where the previous boat yard folks blew through the gelcoat I think I should follow Bill's example and lay a layer of 6oz. cloth over that area and then fair it out. Then after any other things that need work are done (such as the keel damage done by the previous owner) I will barrier coat the entire hull below the waterline. And finally apply bottom paint.
Second I need to finish removing the foam inside the keel and leave that area open to breath so that moisture can go in and out without causing damage.
Looks like my post came after Carl's...
I meant to reply to Ebb.
Carl it seems this type of thing is far more common then I would have guessed.