Catalina 27 Hull Blisters

[new-to-sailing]

Hello! I know this is a well discussed topic but wanted to get opinions on my case of hull blisters. Please let me know any thoughts/next steps or more details I can provide, I've listed some of my general questions below.

My boat (Catalina 27 1989) was hauled out last Friday and today I noticed some blistering in a horizontal line from the bow to just past the middle of the boat only on the port side. The blisters are smaller than a dime (see image of closeup). They run at the same height and just on the port section from bow to just past the middle. I purchased the boat and had it surveyed last winter and these were not noted and all moisture readings were level 1, so they are new this year. The previous owner told me that he fully sanded the hull and painted
Pettit Protect Gray High Build Epoxy Barrier Primer Coat in 2019 with Red Multi-Season Hydro Coat. No work has been done since then on the bottom.

The only other note I'll make is this summer I removed the engine, fuel tank, and essentially had the boat pretty bare most of the summer. This caused the water line to raise quite a bit.

Questions
1. What would cause the blistering only in this one section in what appears to be some kind of pattern?
2. Should I be concerned?
3. What are my next steps?
4. Any other thoughts are appreciated!

[coopec43]

You did quite a bit of work while it was out of the water in summer. Is the cracking on the side where during the heat of the day the sun would be shining? Maybe the High Build epoxy barrier coat couldn't take the heat?

[new-to-sailing]

Originally Posted by coopec43

You did quite a bit of work while it was out of the water in summer. Is the cracking on the side where during the heat of the day the sun would be shining? Maybe the High Build epoxy barrier coat couldn't take the heat?

Boat was in the water all summer, but was doing work on and off to the interior throughout the summer. Just had it pulled 4 days ago.

I was thinking heat as well but this side was the dock side so I figured that would offer it a bit more protection, the starboard side which has no blistering had no boat next to it so got a lot of direct sunlight all summer.