Advice on Stripping bottom paint

I've never seen anyone in the yards down here use a liquid stripper and don't think it works well on bottom paint. Soda blasting the bottom paint off works really well and doesn't hurt the gelcoat in anyway and is very popular. I don't know how many blisters you have, but a lot of times they'll use a peeler and peel the bottom paint off, but it also takes a thin layer of fiberglass etc. If you have tons of blisters it seems to be the preferred method as it takes a lot of the blisters surface away and you let them dry at that point, grind them, fill them, and start putting your epoxy barrier coat on. The boat I had done, they did 6 coats of barrier coating.

Unless you are planning to bring the temp of the matrix up to 90*C for 10 minutes and post curing it, don't bother fixing blisters. Nothing works as the blisters are developed from pockets of uncured styrene in the laminate (polyester post 1972 reformulation to meet VOC requirements). No matter what you do, they will reoccur. Just paint the bottom and save your money. There is no such thing as "a barrier coat" against blisters in polyester regardless of what someone is trying to sell you. You can hide the problem by laminating another layer or two on with vinylester or epoxy then fairing it, but the root problem in the polyester substrata will still be there. Reality is though, it's not enough of a problem to worry about, and when it gets bad enough to start leaking, sink the boat and collect the insurance. When insurance companies start denying coverage because of blisters, you'll know they are an actual safety concern. To date, I haven't heard of such a denial.

Capt Fred

I think that Capt Henning was teasing you about the sinking, but he is dead on about the root cause of blistering - poor fiber saturation during hull lay up. I do know, however, of a couple of boat owners that benefitted from barrier coating. Don't skimp on the number of coats or the qualitity of the materials. Are you in the water year round, or do you haul for the winter? That will make a significant difference in the success of barrier coating.

Blisters are indeed caused by defects in the gelcoat/layup but they are fixable and preventable. The real issue is water getting in between the gelcoat and the laminate.
We fix blistered boats in my yard every day. Leaving them there and painting over them is not something I would advise.
Left un-addressed they will get larger and more numerous. Your boat will get heavier and slower. The cost to repair them will also go up at the problem gets worse. Anti-fouling paint is fairly porous and does little to actually protect the bottom. It just retards fouling and growth.
Blistering problems tend to vary with region. We have pretty severe problems with blisters here. I have seen ten year old boats that have never had a problem come to our area and blister the entire bottom in six months.
We encourage applying an epoxy barrier coat (between 5 and 9 coats) to prevent blisters or to seal in a repaired bottom.
Once water gets into the laminate, there is always the chance that blisters can re-appear even after a good repair job. The best thing to do is to get that epoxy on the hull as soon as you can so you never have to deal with this problem. You only have to do it once. Subsequent bottom jobs can be done over the epoxy job. It is also better not have a "blister history" on you boat when it comes time to sell it.
Pascoe and Interlux paints both have excellent write ups about blistering that should be helpful to anyone wanting the facts.
I would post links to the articles but that is frowned on here. They are easy enough to find.
As a side note, this is one more reason (among many) that I don't like boats with cored bottoms. If the core gets wet, you can actually get blistering that comes from the inside. This is extremely difficult to permanently fix.
If you have a cored bottom take great care to protect the outside with epoxy and the inside by keeping the bilge as dry as possible.

Excellent response, if I could just add one more detail, there is a way to force dry the laminate, using heat and vacuum. Once the gelcoat is peeled, you use this system to force dry the laminate, it works awesome. I dont think I can post the system name on here, I've already had my hand slapped, lol. If you are interested PM me and I will give you the link to the companys website. We have used this system ourselves, it works very well, the jist of the system is it uses heat and vaccuum to pull the moisture out of the laminate. We set the temp at 85 dg c, and usually leave the mats on for appox 8-12 hrs. We then coat the bottom with an epoxy bottom coating, usually about 6 coats.. If you have the bottom peeled, and they do a good job, very little fairing is nessesary.

Be sure to let us know how the bottom looks next year....

update

Just wondering what process you ended up following, if you dont mind, could you state what you did from start to finish..........