I have worked on several gliders over the past 25 years where the =
gelcoat cracks did indeed propagate down into the glass structure. One =
in particular was an ASW-15 where we had to zip off the entire outer =
layer of unidirectional glass in order to remove all of the cracks. =
These were crazing cracks over the entire surface, not stress cracks =
from load (crashing,etc.). A severely cracked LS-4 comes to mind as =
well. With good light and a jeweler's loop, we have noted a good =
handful of other ships that had localized crazing that had gone down =
into the structure. Speaking of down under, the Australians have noted =
this problem and issued an "AD" (or whatever they call it) concerning =
this.

Paul