Bob, why do sailplanes (which spend most of their time in the trailer)
have such a problem, while sailboats (which spend most of their time in
the sun and weather) usually have a good gelcoat?



B Lacovara wrote:

The composites industry has many years of experience and good understanding of
gel coat cracking mechanisms. To address a few of the comments:

1) A gel coat fracture must be removed to the extent of its depth; otherwise
the crack propagation mechanism is in play and will eventually affect the
surface again.

2) A thick and/or flexible secondary coating will delay the re-appearance of
cracks, but not the effects. There must always be concern about an underlying
(but now covered) crack propagating into the laminate.

3) UV penetration of the laminate is a non-issue unless the crack is huge. In
that case the crack itself will be a structural issue.

4) To date, there is not a viable method of "filling" cracks. This is a
function of the inherent surface tension of the potential liquid materials. If
one could fill cracks there is a fair chance two micro-cracks would appear on
each side of the original crack and eventually propagate into larger cracks.

5) To date, no one in the composites industry has come up with a workable
shortcut. A quick fix solution would be worth big bucks, with gliders being a
tiny portion of the overall application.

Hope this helps.

Bob Lacovara