Parallax wrote:
Dont bother. It is my understanding that nearly 80% of all osmotic
blister repairs including overcoating and gelcoat shaving fail.

From what I see around boatyards, that's kind of an overstatement.
Maybe half "fail" but some failures aren't significant. Most of the time
I think it's due to poor prep & not following procedures. Boatyard
workers, and boat owners, are like everybody else in that they do the
things the way they 'think' is right, instead of scrupulously following
instructions.

... I
have asked several marine surveyors if they have ever seen a case of
hull failure due to osmotic blistering and they have all said "No".
It seems to be primarily an aesthetic problem that hardly affects the
sailing ability of the boat.

Probably so, but then how bad would blistering have to get before it
would lead to structural failure of the hull? I have seen "blisters"
that were easily the size of softballs, eating well into the hull
laminate. Is it your contention that this has no impact on the boat?

It seems that if the glass was not fully wetted with resin, you will
get blisters regardless of what you do. This is the case even on very
high quality boats.

??? I'd suggest that "high quality boats" are built with enough
attention to detail that you won't find air bubbles in the laminate. And
I have heard many many explanations for why blisters occur, I don't
think anybody really knows.

... The have no effect on hull strength.

See above. They do if they're bad enough.

Fresh Breezes- Doug King

On Sunday 13 June 2004 1:19 pm in rec.boats.building DSK wrote:

Probably so, but then how bad would blistering have to get before it
would lead to structural failure of the hull? I have seen "blisters"
that were easily the size of softballs, eating well into the hull
laminate. Is it your contention that this has no impact on the boat?

There are no recorded cases of sinkings or structural failure caused
by osmosis. OTOH it is unlikely that any sensible person would put to
sea in a seriously damaged hull to tempt such an event.

In general the repair of small osmosis blisters has more to do with
maintaining resale value than with safety.

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