I’ve worked on boats with great factory gel coat jobs, and others with not so good gel coat work. More specifically, on some boats, usually thicker gel coated, with lots of spider cracks and missing gel coat chips and chunks, and some others, while heavily used and scratched, with thinner gel coat and fewer issues.
I have noticed is that some more vintage gel coat was applied thinner than as on later models of the same boats from the same company/factory, and the thinner examples seem less prone to spider cracking. It makes sense (I guess) that thinner gel coat would be more flexible, and less prone to splintering on impact, but I am far from a gel coat guru.
At the same time that thinner vintage gel coat has also proven less prone to busting off chunks; maybe it takes an unattended spider crack to get those missing pieces started flaking off. That also, to me, makes sense, and may be a reason to attend to spider cracks before broken pieces peel off entirely.
I’m thinking of a friend’s hard used and abused early glass MRC Explorer I rehabbed 20 years ago, and the ’75 Hyperform Optima I am currently working on, both with thinner, more flexible gel coat, both sans spider cracks or missing chips.
The 46 year old Optima has 1,000+ scratches on the bottom, but zero spider cracks, only a few tiny pieces of gel coat missing. Cumulatively all of those missing pieces are the size of my pinkie nail. Sanded and filled with thickened G/flex before bottom paint.
P9040018 by
Mike McCrea, on Flickr
Teeny tiny missing chips, nearly a “why bother?”. Eh, I have time, and G/flex, and Colloidal Silica powder, and filling those teensy chips only took a second. And some cure wait-time before re-sanding and painting.
Just curious if anyone has an explanation for gel coat variances. Was it factory prep work, process, technique, chemistry? Was there some superior gel coat used in the ’70’s & ‘80’s that fell out of favor, became too expensive compared to a lesser alternative, was banned by OSHA for toxicity or etc?
Or are some hulls just outliers, made by a careful shop with skilled employees, and some made on Friday afternoon by folks ready to call it a day?