My boat had numerous layers of paint when I bought it. Having a bad case of "do it yourself disease" I stripped the bottom myself with Peel Away 2. It took more material than I thought by I eventually got there. Interestingly enough the boat already had barrier coat on it (except for six squares where jackstands were... bet the previous owner didn't know that). I sanded everything down to 80 grit and applied four more coats of barrier coat.
Now my boat has a signal coat of red hard paint and two coats of blue ablative. I swore I was never going to deal with build up again.
PSC 31 Journey