Wow, that is quite a nasty surprise, I applaud your will power and knowledge to tackle this job yourself. It looks like your boat is somewhere inside, is that correct ? At least that makes work a bit easier, no fear of rain.
The bottom tuned into a nightmare with grinding, a huge section of deep reglassing, whole bottom glassing and barrier coat. Good news, not a new blister in 15 years.
Goes to show people, a few blisters might be just that, or just the beginning.....