johnsw":3fa348i7 said:
Anyone have any experiences with gelcoat spider cracks? Seems like more of a cosmetic issue, but do they eventually stabilize or just keep going?
All I can offer is some info I got last weekend with a member of my boat club who has a fiberglass boat restoration business. He does everything from Awl Grip paint jobs to complete stringer and transom rebuilds.
Firstly, remember that the tensile strength of gelcoat is very hard, therefore it is very brittle. Stress cracks are cosmetic and occur when the substrate layer moves and the harder gelcoat can't "flex" with it, so it cracks.
Second, my friend reports that the gelcoat made nowadays is not on par with that made many years ago. This is not Parker's fault, but that of the gelcoat industry and environmental standards. Regarding non-white or beige gelcoat colors, he further advises anyone who really wants a colored hull to go with Awl Grip paint job and not with colored gelcoat ... he showed me a green hull not 4 years old that was already severely chalked. Nor is gelcoat applied as thick as it was on older boats, though here too, I would surmise that Parker is among the best.
One other reason for stress cracks appearing on new boats is that many companies pull their boats from the mold far too soon and apply deck hardware that gets torqued tight. The glass on the outside may be hard, but inside its still curing, or "green" as they say in the trade. Now I would bet that Parker leaves their boats in tbe mold longer than just about anybody else, but in the end, boats don't sit in the molds curing today like they did 10 years ago.
With all that said, I'd bet the predominant reason you see it where you do is that's just about the entry area where the hull is slamming into the waves ... the hull moves up a bit, as does the deck, but the deck is constrained from "above" by the rail mounting pads. It is the pad that is being forced "down" into the deck and thereby causing the stress cracks ... by my best guess anyway.
You could loosen the rail all the way around and add a suitable 1/16" to 1/8" thick heavy durometer washer between the deck and rail ... if you really wanted to go to that trouble. I'd remove one rail bolt at a time, having done a Parker rail before
.
Normally, stress cracks will stop once they reach the pont of flexation. Yes, you can grind them out with a dremel "V" bit and then fill them ... but if the cause is still there, then yes too, they will reappear.
Hope this helps ...
