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Anyone ever hear of this? Is it even possible? I've talked to some people that have been in the business of boats for a long time but it was news to them. I'm not talking about boats that are moored either although I'd like to hear if that happens as well. This was one reason given not to go with a glass boat.
 

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Yes, absolutely according to Hugo De Plessis (Fiberglass Boats). More worrisome is the stringers. Absorbing water and then dry rotting. Newer FRP boats use non wood material for stringers and bulkheads to overcome this problem.

All glass exposed to water does better when it is surface cured or protected by gel coat. Any hull damage that chips out the gel coat can allow water to get into the glass. It wicks like a candle wick through the glass fibers that are not completely encased (wetted out) during the manufacturing process. So if you chip the hull it is best to sand out and fill the spot as soon as you can. Better if you can repair the gel coat too.

The water can actually combine with uncured resin and dissolve the good resin.
 

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Ok that's assuming one, the stringers are made of wood. Not an issue with the boats I'm considering (at least one of them will have to check on the other). Two, the boats most definitely are gel coated so not an issue either.

Sounds to me like more of a problem if there is a flaw in the boat but not necessarily an issue otherwise. Keep it maintained and you shouldn't have a problem right? I mean you could make the same arguement for an alum. boat getting crevice corrosion over time.

Thanks for the info. At least now I know it is possible under the right circumstances. Otherwise I'm not going to worry about it. Certainly didn't with my last glass boat.
 

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Even new the damage starts with the first hole you drill in the boat to attach some boat jewelry.

Or the first dock rash.
 

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Boat US who I have my boat insured through sends a monthly magazine out and it has a lot of good info. I can't remember the issue, but it seems it was about a year ago it had a good article and actually show the color change in fiberglass that had absorbed water. Gel coat can absorb water as well and into the glass it goes, plus a lot of the water can get into the glass from inside the boat. Most all boats will have water in the bilge due even if they had a self bailing deck.... it seems to get in there somehow.... not much, but it only takes a little to slosh around.....

You can probably do a quick net search and get lots of info on this topice..... probably not to big of an issue, but it can happen.
 

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Some random thoughts on FB, wood, and resins.

While it may seem like a good idea to completely "seal" wood stringers by encasing them in resin and fiberglass, - in fact this creates an ideal environment for rot once water inevitably makes its way into the wood. This chronic problem with wooden stringers rotting in FB boats is a major reason I believe wood boats get such a bad rap.

The problem is on a microscopic level glass fibers are very smooth and chemically inert. This means no kind of resin, polyester (FB) or epoxy, can create a true "chemical bond" with the glass. This leaves a "mechanical bond", - which still can be very strong, but the smoothness of the glass fibers means that excess flexing or stressing can break the mechanical bonds with resin. What then happens is something similar to "metal fatigue" in that the bonds begin to fail along the length of the fibers from the original point of damage (sorta like a crack in a windsheild). Anywhere the resin/glass bonds have failed, creates an almost magnetic attraction for water to "wick" (as mentioned) along the fibers where the resin has separated. So yes, it is very important to repair damaged fiberglass ASAP, because once the water starts working it's way in, its very difficult, - if not impossible to completely remove.

If I had an FB boat, I would probably do my repairs with marine grade epoxy instead of polyester resin. The reasons are that epoxy has a much higher strength to weight ratio, it is more flexible and therefore less likely to crack and separate from the fibers, AND it is semipermeable to water vapor meaning it can "outgas" excessive water buildup. Also it bonds very well to cured FB resin (you would only have a mechanical bond anyway with FB resin).

The fact that epoxy is permeable to water vapor is one of the reasons it's so well suited to wooden boat construction. Unfortunately fiberglass will create a vapor barrier even when used with epoxy resin. So when building a wood/epoxy boat, care needs to be excerised to not completely encase wood when reinforcing with fiberglass cloth or tape.
 

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Anyone ever hear of this? Is it even possible? I've talked to some people that have been in the business of boats for a long time but it was news to them. I'm not talking about boats that are moored either although I'd like to hear if that happens as well. This was one reason given not to go with a glass boat.
Yes, fiberglass can and will absorb water. If you are worring about the possibilty of this happening to a non-moored boat, loose your concern. If you are worried about it enough to concider an alum. boat over glass, well alum. has far more issues.

Will fiberglass abosrb water enough to create a problem - Probably not
Will alum. corrode enough to create problems - Guaranteed
 
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