Well I finally took the 2nd boat that I bought out of the water today. It had been in the water for about 5 years or better it had had a coat of VC 17 and needless to say it was long gone. The growth on the bottom was about 1 inch thick( moss and grass looking stuff.) it came off real easy with the pressure washer the boat was in the lake here . I found areas that showed the fiberglass stranding and no blisters this is on a 1974 San Juan 24 I was surprised. Not sure what I will be doing with the boat but it is for sale and I will work on it as the time permits right now she looks horrible. will let everyone know as the time goes on.
Is there a bottom primmer that is good to use? I would rather not use a barrier coat just to much trouble. I do have stranding showing in places.
do you plan to keep it on the trailer, or in a slip?
I'd at least roll on a few coats of epoxy. And the Gougeons sell and additive that is sort of a barrier coat.
Otherwise you risk getting the fiberglass wet, which could lead to blisters or delamination
After treating the small blisters and sanding fair - I used VCtar on the Hunter 23 Sooner - 2 quarts did 3 coats +.
I was amazed how that stuff went on and self leveled. Was able to put all 3 coats on in one day. 3 coats of vc17 made the bottom slick as a babies butt. Just cant beat it for a trailer sailer - it's hard doesn't scuff off and everything wipes off easily. Wouldn't put VC17 on if your going to leave her in the water tho. Nothing better than your boat trying to scoot out from under you with a small puff.
jim
Look into Copper Coat.