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From: (no name) (no email)
Date: Thu Jul 03 2003 - 15:43:09 EDT
Bryan Genez writes:
>Core rot is only one cause of delamination. More often, the problem
>is in
>the layups themselves. In these, the core material is irrelevant.
True.
>Airex also has a wonderful
>characteristic of changing shape under heat; you can literally see
>waves
>develop in an Airex-cored boat that's in the summer sun.
Assume you are talking about decks, not hulls.
>...as do some high-cost semi-custom builders.
Unfortunately.
>FWIW, earlier this year, I removed virtually every piece of hardware
>from
>the coach roof of my 26-year-old, balsa-cored, production boat. None
>of the
>penetrations had been sealed. None leaked. No rot. I don't disagree
>that
>the holes should be sealed, and I sealed every new hole that I
>drilled. But
>I do question the "sure to happen" statement. Let's just say the odds
>of
>destructive leaking increase unless the core is sealed.
Personally, I think you were very lucky. Others have not been as
fortunate.
>Not necessarily. Fiberglass is notoriously low in abrasion
>resistance.
Absolutely true, especially if it is a polyester laminate using mat and
woven roving.
OTOH, epoxy and knitted glass laminates offer better abrasion resistance.
(You would be amazed how fast it can render a 16 grit sanding disk
useless<G>)
How much better I leave for others to determine.
>Put
>a fiberglass boat on the rocks or in coral with the sea action adding
>a bit
>of motion and it will get chewed up in short order.
In my own case, having a sealed internal ballast basically makes the
issue moot; unless, the grounding were to happen at the back of the keel
where the bilge is located.
Those with an external lead keel also are in pretty good shape.
Either one goes to hell in a hand basket if the tide goes out leaving the
boat on it's side trying to defend itself from wave action; however, a
cored hull has a better chance than a solid skin hull.
>The sandwich core
>will
>absorb some energy from impacts...for example, the oft-repeated
>collision
>with shipping containers...but it will do little to nothing to limit
>damage
>from a hard grounding, unless the boat is refloated quickly.
The main purpose of the core material is to protect the integrity of the
inner skin of the sandwich in the event of a collision.
Under those conditions, the outer skin can be considered as sacrificial.
Lew
S/A: Challenge, The Bullet Proof Boat (Under Construction in the
Southland)
Visit <http://home.earthlink.net/~lewhodgett> for pictures
There are no problems, only varying degrees of challenging opportunity.
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