This is what I have used to strip bottom paint
off my boat.
Klean-Strip GAF354 Fiberglass Paint Stripper
A milder citrus stripper is available at the hardware stores.
READ and follow instructions for these products.
I rough sand the painted surface to break the skin and apply the stripper. Let the stripper do the work as soon as stripped area wash to decontaminate the surface.
Have you tried using a straight razor blade and scraping the paint
off instead of sanding it off? In areas where paint
isnt stuck well it flakes off easily. Change the razor blades alot.