Gordon, thank you for your input.
As background info yes previous coat were ablative paint.
I am doing myself the best favor that is to say asking advises on the subject from more experienced people on the best forum.
If I can clarified my questions, I try to see if only antifouling is enough to protect fb hull from water ingress (or any damage) or if I need any undercoat,and especially on chipped areas. Doing it fast is something, doing it cheap also, just try to do it right
L.