This video provides a great example of a bottom side boat inspection. It is undertaken by using a scraper to remove the top layers of the substrate, once the underneath layers have been revealed a further investigation is required to see what paints, resins or anti-fouls have been used. In this case of this repair, the previous owner has sanded the osmosis blisters and chipping that had occurred on the original Gelcoat. The blisters were filled with an epoxy putty with a barrier coat to finish. Unfortunately, the paint did now have a strong mechanical bond because the surface had not been properly keyed in.
Notably, this video offers some great advice: when you’ve got a boat that is this big and you’re not going to pull out of the water regularly, you better go to great lengths to do it right.