Karena,

In all the posts above I haven't seen anyone mention "Gelcoat Blistering" .... these are caused by moisture being trapped between the gelcoat and the underlaying fiberglass. This was a big problem on manufactured fiberglass boats, big and small, if they were left in the water to absorb it over time with boats produced in the late 70's through the 80's. How do I know .... I have a set of TheMightyHobie18 hulls currently in my backyard that will need to have the gelcoat sanded off to remove these "blisters". These hulls were bottom painted which I removed ... discovering the extensive gelcoat
blistering.

Now I think that the solution was that the hull was sanded ... then a coat of epoxy (or coats) were applied ... then bottom paint was used as a outer coating. We had a family friend who had to go through this process w/ his 36ft sailboat at the time.

So I would suggest that some questions/investigation is in order before you use a roller/paintbrush .....

Harry