Cored and Solid Fiberglass Hulls

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I got news for the solid glass types.... even those hulls can have hydrolysis so bad that a significant portion of the hull may be severely degraded and you don't know it.

I ground through 1/2 inch of glass laminations in a 1 inch thick hull and found the resin/layups were no longer anywhere near design strength and full of water. 2 trash cans full as per the pictures.

2 surveyors hammer tapped away and never found a 6 foot by 6 foot area of severely damaged hull.
I have seen your pictures of this that you previously posted, how did you know you had such a severe problem?
 
I have seen your pictures of this that you previously posted, how did you know you had such a severe problem?
I wanted to grind off the bottom paint as it was in terrible shape for a barrier coat and new bottom paint.. Got started and noticed many tiny blisters and quite a few big ones. When I starter on those, the mat under the gel coat was bad and I started peeling that off. As I progressed, I found more and more bad spots. Wound up grinding all the gel and matt off down to the roving. Where the roving was soft or oozing water, I kept going. Fortunately, most spots were pretty small areas but much larger than the evident blisters. That's why I say blister aren't usually a problem, unless they are signaling a bigger problem which blister repair doesn't solve.

The only big area was a pain to layup by myself...but I got it done and sheathed the whole hull in a layer of cloth and good layers of Interprotect 2000.

2 Subsequent surveyors were impressed with the repair (though not cosmetically perfect) and not one blister after12 years.

I have worked on plenty of different hulls and can say there are almost always more problems with at least parts of them that go undetected till you start tearing into them, often because of other issues.
 
I wanted to grind off the bottom paint as it was in terrible shape for a barrier coat and new bottom paint.. Got started and noticed many tiny blisters and quite a few big ones. When I starter on those, the mat under the gel coat was bad and I started peeling that off. As I progressed, I found more and more bad spots. Wound up grinding all the gel and matt off down to the roving. Where the roving was soft or oozing water, I kept going. Fortunately, most spots were pretty small areas but much larger than the evident blisters. That's why I say blister aren't usually a problem, unless they are signaling a bigger problem which blister repair doesn't solve.

The only big area was a pain to layup by myself...but I got it done and sheathed the whole hull in a layer of cloth and good layers of Interprotect 2000.

2 Subsequent surveyors were impressed with the repair (though not cosmetically perfect) and not one blister after12 years.

I have worked on plenty of different hulls and can say there are almost always more problems with at least parts of them that go undetected till you start tearing into them, often because of other issues.
Thanks, I was just curious. I don't have any blisters or signs of issues, just trying to add to my knowledge bank.
 
2 surveyors hammer tapped away and never found the 6 foot by 6 foot area of severely damaged hull.
Sounds like you needed a 3rd surveyor. There is no way that degree of damage should be missed.
 
Sounds like you needed a 3rd surveyor. There is no way that degree of damage should be missed.
You say that......and most of the time it should work that way...... But I have read where this kind of damage IS easily missed by the tapping method.

From what I can piece together, severe hydrolysis can be to the point where delamination has not yet occurred, but the majority of the resin has dissolved and the laminates are sill tight enough to sound OK but can be easily separated once something starts the process like a good shot to the hull.

Think of it like rolls of tape. Some rolls are really hard to pull a strip off, others are pretty easy because the sticky between them is not as strong. But if you hit the side of the rolls of tape, they feel all feel just as solid. there's no real space between them (delamination) so the sound is not distinguishable yet.
 
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A cored hull French trawler brand boat we inspected had multiple cabin portlights leaking rainwater due to poor sealing. What might be happening with underwater hull openings?
If you mean Beneteau, any through hull areas are solid GRP (see video I posted earlier.. which I found while researching cored hull horror stories for my pre-purchase investigations.). As @Comodave said, most issues will come from subsequent owner’s drilling where they shouldn’t be drilling.. it’s why it took me over 2 years to find an unmolested one..
 
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