Your boat is either suffering from osmotic blistering or you are very into photoshop. If the blisters are only below the gel-coat (or 2 part polyurethane yacht paint) I'd simply let them recede by themselves. (Judging from the pictures, this is what I'd do)

If OTOH they are deeper down, inside the glass, they need to be opened up, sanded out and filled with epoxy filler. If the damage is extensive you have a more serious problem possibly requiring removal of the gel-coat and long term drying of the laminate... Let's hope not.

Superficial osmosis is (in my experience) mostly caused by almost constant contact with water. If in storage, wet grass will do that, or even a moisture soaked tarp the boat may have been in (almost constant) contact with.

I would be very careful with heating up the blisters. If the fluid inside boils I would be very afraid it would cause extensive structural damage to the laminate.

Dennis