Bottom paint can prevent gelcoat blistering. Gel coats are not 100% impervious to water penetration.
In the ocean the bottom paints are a necessity to prevent barnacles. If the boat is on a trailer and comes out of the water you should never have a gel coat problem. As far as bottom paint contamination, have any of you seal coated your driveways? Installed new carpet? smoke cigarettes? stand near the nozzel when you gas up your cars? use cleaning solvents? use fertilizers? pesticides?
Here is a link to the bottom paint that SeaRay uses. It is water based and they claim to "Easy to apply, environmentally friendly and safer to use".
http://www.pettitpaint.com/fileshare...ds/1184006.pdf
Carefully follow the instructions and watch for airborn particles. Educate yourself before you try to do this in your back yard.
P.S. I had my bottom paint re-done last year after 10 years in the slip. I leave the boat in the water during the winter. It is inside with bublers that prevent ice from forming.