I have experienced a similar problem on my Shearwater hybrid. I posted a question a few weeks ago regarding this but recieved no replys. I hope someone comes through on your post.

Jim L

PRINT THROUGH
"A distortion in the surface of a part which allows the pattern of the core or fiberglass reinforcement to be visible through the surface. Also known as print out, telegraphing or read through"

The combined effects of the sun's heat on the fibregalss and epoxy and the shrinkage on the outer paint or varnish allows the mesh to slightly show through.  Mine did the same thing after a few days in the hot sun especially while being car topped.  It has not gotten any worse and I'm not too worried about it.  I'm not sure of an easy solution.  More to come from others I'm sure.

Chris

For what it's worth, mine did in fact get worse.  I always attributed it to not having enough UV protection since I never bothered varnishing my boat.  It was definitely worse on the hull, so I think rubbing also had something to do with it... just general wear and tear on the hull.

I'm retrofitting my boat now so I'm going to give it another dip in epoxy to hopefully (re)fill the affected areas and then actually varnish after I get the new deck on it.  

Well, this seems to be a problem for many, but no one has said how to avoid it.

Please, someone has to have an idea

Kev,

The only way I've heard to avoid it is to put a ridiculous number of coats of epoxy followed by a ridiculous number of coats of varnish (preferably spar with high UV protection).  

As far as I can tell, it hasn't decreased the strength of my boat at all and most people don't notice it as an aesthetic concern.  They're usually too busy being awed by the fact that it's a home-built boat to bother with any of the minor issues.

FrankP

Sam Devlin discusses this issue in his book.  His "cure" is to be sure that the epoxy fully cures before paint or varnish.  In good heat or sun if possible for something like a month.  After this the print through is reduced.  Refinishing of the surface will often eliminate much of it if it does happen.  Read Sam's book for more info.