I'd fix the damage and properly bottom paint. An undesirable job, but
if you don't do it they won't go away nor will they get better.


And if they're between the gelcoat and the skinout mat (as 99% of such blisters
are)
they are a cosmetic problem only. If you lose a lot of sleep worrying about how
your boat looks under the waterline, spend a few thousand to fix them.....but
there is a high probabilty that unless you peel the bottom and relaminate with
vinylester (which is what the newer Bayliners have used for several years) any
lesser fix will be temporary, at best.

Osmostic blisters are a separate problem from delamination. Delamination is
very serious, and could compromise the strength of your hull. What you are
describing sounds like osmotic, gelcoat blistering.

Old wives' tales:

1. Osmotic blisters are the first stage of delamination.

2. Blistering causes the laminates to soak up water until the fiberglass gets
"waterlogged."

Worst effect of blisters is the resale problem. In the Pacific NW, about 90% of
the FRP boats more than just several years old have a few blisters, most have
dozens, and some have many more. When these boats are surveyed, the surveyors
note the presence of the blisters and tap carefully around them to make sure
there isn't any delamination. 90-some percent of the time, there is not any
delam and the surveyors categorize the problem as cosmetic/non-structural.

Here's where the fun begins. The buyer will look at the survey and holler,
"Blisters? Well, let me tell you: I'm still going to buy the boat but I need a
big discount!" The seller will say, "Those blisters have been there for years
and they're no big deal......"
and the re-negotiations begin.

Most of the buyers who get an additional discount for blisters enjoy the
discount but do *not* spend the money to fix the boat. In a few years, when
it's their turn to sell the boat, they have done a philosophical 180 and will
be quick to tell their own prospective buyer that the blisters are
"no big deal, just cosmetic."

Good article on blisters, from a controversial source but I think he has this
fairly well understood:

http://www.yachtsurvey.com/BuyingBlisterBoat.htm