bottom job advice
I'm rehabilitating FS #1632 and working on the bottom. The plan is to take off the ablative bottom paint, sand to gell-coat, fair, apply Interprotect for a barrier coat and repaint. I did this several years ago with an FJ of similar vintage, so while no expert I understand the basics. (In that case, a turquoise boat with worn gel coat was overcoated with yellow oil house paint.)
The detective work comes in with the sanding to gell coat.
The deck and cove stripe at least of this early 1970s Douglas Scot appears to be the classic turquoise/light blue of the era. Below the ablative bottom paint is a coating of white; I THOUGHT that was another layer of old bottom paint, judging from the square flaking in sections. But where I started to sand below the white, and upon closer inspection, where the next laye ris revealed via sanding in scrapes and gouges, I'm not able to discern gell-coat.
1.) From other FS folks, is it likely that the bottom gell-coat is a different color from the cove stripe?
2.) Has anyone seen gell coat flaking off in squares (similar to old, lead house paint)?
3.) Assuming the while is gel-coat AND it's in bad shape at points, would you sand it all off and put a barrier coat or only remove it in questionable areas, then repair by fairing?
Thanks for any advice.