I decided to strip the bottom paint and put on an Epoxy barrier coat. I scraped off the loose blue bottom paint and then sanded off the VC17 that was next to the gell coat. It was easy going getting off the blue as it didn’t adhere very well to the VC17.
There were only a few very small blisters (5mm) close to the rear of the keel joint.
One suggestion is to use a good grade of sandpaper – sounds trivial but the expensive sand paper lasted much longer than the cheap stuff.
I used Interlux’s 2-part Interprotect 2000E, alternating between gray and white. I was able to squeak out six coats out of six gallons, including a sand between coats 5+6. I then put on two coats of red VC17. It was a bit of a challenge getting the curved waterline on the bottom of the hull where it’s flat. I taped then drew a line with a pencil and string – it’s a compound curve so a bit tricky, but when I was happy I just free hand trimmed the tape with an xacto knife – it came out pretty well and whatever imperfections there are won’t be seen as it’s under the boat!