JJ - Good point... the distinction is the crack mechanism. The purely cosmetic
cracks (fortunately a majority of glider cracking) are confined within the gel
coat film, and are a product of the performance of the gel coat. More critical
in nature, are cracks resulting from localized laminate fatigue. Many times the
first indication is a gel coat crack *before* the laminate actually shows a
visible crack. This is the situation of concern if the cracks are covered. The
laminate should be thoroughly inspected after the gel coat is removed,
particularly on older, high time or hard use ships.

Bob


I have ground out literally hundreds of cracks in gel-coat that went
right down
to the fiberglass laminate. To date, I haven't seen any gel-coat cracks that
entered the underlying structure. Not saying it can't happen, just haven't seen
it in going on 30 years of smelling fiberglass dust. BTW, I'm talking about
pure gel-coat cracks, not surface cracks that were caused by laminate failure
underneath. That is the first question that a repairman asks, Is this a
gel-coat crack or has the underlying structure moved?
JJ Sinclair