PorFin beat me to it but the resin makes a big difference. If the hull was coated 10 years ago with polyester resin it would not be more effective at stopping water absorption than the original material, also polyester most likely. Epoxy is the best choice for barrier coats (Interprotect is epoxy) and 5 coats or more are necessary to build up enough thickness.
As far as the bubbles in the anti fouling paint it could be causes by not prepping correctly.
Living aboard in Victoria Harbour