http://www.hotvac.com/process/default.aspx

"HotVac treats boats by…

* The thorough removal of absorbed water from affected hulls.
* The removal of acids, glycols and other organic compounds that
cause corrosion, glass to resin bond weakening, delamination and
blistering. "

XXXXXXXXXXXXXXXXXXXXXXXXXXXX

http://www.boats.com/content/default...tentid=1899how to
tips
Fiberglass Blisters
Effective prevention and treatment

"The hull must then be dried, to get the saturation of the laminate
below 50 percent, which can take considerable time, as reflected by
the following table:

Temperature 50% Relative Humidity 25% Relative Humidity
100 F l6 days 9 days
83 F 32 days 18 days
65 F 64 days 36 days
47 F 128 days 72 days"

I dont have the reference handy but the amount of water a hull can
absorb is quite significant, and yet not have any ill effects although
not universal. I guess some of the issue is where the boat is
seasonally hauled out and whether it is fresh or salt water...