I've read a few comments in various threads that refer to 2 pack being applied without shot blasting. Pretty sure some have even suggested it can be done without going back to bare metal.
Two good outfits I know who do it swear that's wrong, and that it really needs shot blasting to adhere properly. They both talk disapprovingly of those who use it without that level of prep, and how often they have seen and had to deal with problems resulting.
You might think, "Well they would say that," - after all they both offer shot blasting and 2 pack application! But I've seen examples of it flaking off when the person who did it swears they got right back to bare metal. And I'm not just talking below the waterline (although I do also know someone who bought a brand new boat by a pretty well known maker whose boats go by his name, where the 2 pack epoxy below the waterline started flaking off within a year).
I don't have any 2 pack plans right now, I'm only stirring, sorry, I mean asking, as I think it will be interesting to hear what people's views are and how they back them up, and what their experiences have been.