I recently hauled my boat to do a bottom job. To my dismay, there were quite a few blisters. The PO had applied a West Systems barrier coat 4-5 years previously and was pretty surprised to see that it still blistered rather badly. He said he followed the West Systems directions to the letter. Others that know him said they saw the boat at various stages of the process and it looked like he was taking great pains to do it right. Now for the controversy. The guy that redid the bottom for me is well respected in this area and has over 20 years experience in this type of work. He was NOT surprised. He said that it has been his experience that epoxy bottom coatings do little to prevent blisters because "water will find a way in". He told me to save my money and instead of the time and expense of applying a barrier coat, pull the boat out every 2-3 years, clean up the blisters that appear and apply a good bottom coat. What do you folks think?
Barrier coats
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Blisters
There appear to be some mixed opinions on this, and I'm not sure what mine even is. I have not so far had a blister problem. Knock on wood. But I have read a few things by some who are supposed experts, and have seen different theories. Think I read a link on Don Pacoes pages some time ago, that said basically that a barrier coat at best is a short term preventative. Others swear by barrier coats, although I suspect some are just selling a product. I seem to do pretty good using Trinidad, and do a bottom job every three years. Guess I will just keep on doing what I been doing.
There appear to be some mixed opinions on this, and I'm not sure what mine even is. I have not so far had a blister problem. Knock on wood. But I have read a few things by some who are supposed experts, and have seen different theories. Think I read a link on Don Pacoes pages some time ago, that said basically that a barrier coat at best is a short term preventative. Others swear by barrier coats, although I suspect some are just selling a product. I seem to do pretty good using Trinidad, and do a bottom job every three years. Guess I will just keep on doing what I been doing.
I, too, don't recommend barrier coats
The people who make barrier coat products would like everyone to use them, yet I have serious doubts about their ability to really protect the bottom of a boat. A lot of blisters are due to how your boat was laid up during manufacture. If any number of critical factors were compromised at that time, you may get blisters regardless of what you put on the bottom of your boat. I agree with the advice you got: open, dry out, and refill any blisters you now have -- put on some bottom paint and then go sailing. Be prepared to make this task a part of your annual maintenance plan. If you boat has a serious case of the pox, that is a bottom totally given over to blisters, think about getting another boat....
The people who make barrier coat products would like everyone to use them, yet I have serious doubts about their ability to really protect the bottom of a boat. A lot of blisters are due to how your boat was laid up during manufacture. If any number of critical factors were compromised at that time, you may get blisters regardless of what you put on the bottom of your boat. I agree with the advice you got: open, dry out, and refill any blisters you now have -- put on some bottom paint and then go sailing. Be prepared to make this task a part of your annual maintenance plan. If you boat has a serious case of the pox, that is a bottom totally given over to blisters, think about getting another boat....
I have mixed results. In SoCal, most of us use a hard epoxy anti-fouling and often, a dive service (a whole other story). Late 70's to mid 80's boats tended to get blisters, I'm told in part because of changes to resin formulae. Regardless, my 60's and early 70's boats did not get blisters. My Dad had a 1984 Lancer, and we did put a barrier coat on it. I got a 1990 Hunter, and four years into it, I called the factory who suggested I NOT barrier coat it. Nine years later, no blisters. My 1994 Hunter has (fingers crossed) no blisters either. In fact, NONE of the boats did, even my Dad's which I would have bet would have been the most likely candidate. A couple of years ago, I asked one of SoCal's most repected yards if barrier coating was a good idea in view of our boats not drying out. He said it is a lousy idea. So, unless you plan on drying out for a very long time, or force-drying for a couple of months, it may aggravate the situation instead of helping. I think. Rick D.
19 Years - and not ONE single blister!
My experience: Our boat was barrier-coated when it was new and there has never been a blister, and that was 19 years ago ('88 H35). And, our boat has never been hauled for the winter - it stays in the water year-round. By comparison: Several years ago there was an article in BoatUS about Hunter 35s written by an east coast surveyor or writer, based on his small sampling, said they "all" had or get blisters. I wrote them and said I disagreed with his statement because of my experience. One can analyze this any way they want but I think the barrier coat on my boat has had a lot to do with the prevention of blisters. Around 1990 or so, ~17 years ago, I put on a PYI shaft seal which has basically kept the bildge dry and dusty. This may have helped too. The combination of the two, dripless shaft seal & barrier coat, has probably helped a lot. The history of the boat still has some items which are unclear or raise questions. From the original post it is unclear how long the boat was in the water, if ever, before the first person did the barrier coat. If it spent time in the water it's important that the hull be dried out before the barrier coat is applied otherwise the water is basically locked in. Also, it's unknown how thoroughly the hull was dried out. If it was dried out, how was it determined it was really dry? Maybe just the outer surface was dried? If it took a long time for the water to be adsorbed then it would take a long time for it to become dry. Heat can speed up the drying process but even so, it will take time. It seems if the hull is getting blisters then either the barrier coat was too thin or there was moisture locked in before the barrier coat was applied. The epoxy coats are thin and it takes a number of layers to do a good job. The devil is in the details and that's my two cents. If I got a new boat tomorrow I'd certainly barrier coat it.
My experience: Our boat was barrier-coated when it was new and there has never been a blister, and that was 19 years ago ('88 H35). And, our boat has never been hauled for the winter - it stays in the water year-round. By comparison: Several years ago there was an article in BoatUS about Hunter 35s written by an east coast surveyor or writer, based on his small sampling, said they "all" had or get blisters. I wrote them and said I disagreed with his statement because of my experience. One can analyze this any way they want but I think the barrier coat on my boat has had a lot to do with the prevention of blisters. Around 1990 or so, ~17 years ago, I put on a PYI shaft seal which has basically kept the bildge dry and dusty. This may have helped too. The combination of the two, dripless shaft seal & barrier coat, has probably helped a lot. The history of the boat still has some items which are unclear or raise questions. From the original post it is unclear how long the boat was in the water, if ever, before the first person did the barrier coat. If it spent time in the water it's important that the hull be dried out before the barrier coat is applied otherwise the water is basically locked in. Also, it's unknown how thoroughly the hull was dried out. If it was dried out, how was it determined it was really dry? Maybe just the outer surface was dried? If it took a long time for the water to be adsorbed then it would take a long time for it to become dry. Heat can speed up the drying process but even so, it will take time. It seems if the hull is getting blisters then either the barrier coat was too thin or there was moisture locked in before the barrier coat was applied. The epoxy coats are thin and it takes a number of layers to do a good job. The devil is in the details and that's my two cents. If I got a new boat tomorrow I'd certainly barrier coat it.
Interlux 2000
I am one of the believers. I have done three boats with Interlux, only one had blisters, the other two was preventative. IMO The key to a proper barrier coat is a dry boat. This requires hauling the boat ruff sanding the bottom to open all the blisters and let dry, I mean dry. May have to leave the boat out for a year depending on how bad it is. If you barrier coat over a wet bottom, or over blisters of any kind, the blisters will come through the barrier coat. If you use the Interlux products, follow the directions exactly. Two part epoxy in my case lasted over ten years. After that I heavy sanded and put three more coats back on just to make me feel good. On the boat with blisters -- it was out of the water for eight months but we had heavy sanded it in the fall and opened all the blister up. It was dry when we did the barrier coat and no blisters came back. Another tip is to put your first coat of bottom paint on when the last coat of barrier less than cured, but not wet. I don't know anything about the West system but I have seen friends use it and were happy with it.
I am one of the believers. I have done three boats with Interlux, only one had blisters, the other two was preventative. IMO The key to a proper barrier coat is a dry boat. This requires hauling the boat ruff sanding the bottom to open all the blisters and let dry, I mean dry. May have to leave the boat out for a year depending on how bad it is. If you barrier coat over a wet bottom, or over blisters of any kind, the blisters will come through the barrier coat. If you use the Interlux products, follow the directions exactly. Two part epoxy in my case lasted over ten years. After that I heavy sanded and put three more coats back on just to make me feel good. On the boat with blisters -- it was out of the water for eight months but we had heavy sanded it in the fall and opened all the blister up. It was dry when we did the barrier coat and no blisters came back. Another tip is to put your first coat of bottom paint on when the last coat of barrier less than cured, but not wet. I don't know anything about the West system but I have seen friends use it and were happy with it.
Comparable story
According to, I think it is Don Pascoe, the blisters are a result of the lay up of each individual boat. According to him, one boat out of a mold will never have a blister, and the next boat, out of the very same mold can have them by the thousands. If there are small voids between the gel coat and the glass behind it, ou will get blisters. No voids, no blisters. My S2, which is nearly 30 years old now, ( 1980 Mocel ) has never had a basrrier coat applied, and last time it was hauled, 18 Months ago, there was not a single blister to be found. Troendle Marine in Pennsacola also does not recommend a barrier coat. He impressed me quite a bit with the quality of work his yard does, and his overall knowledge of boats in general.
According to, I think it is Don Pascoe, the blisters are a result of the lay up of each individual boat. According to him, one boat out of a mold will never have a blister, and the next boat, out of the very same mold can have them by the thousands. If there are small voids between the gel coat and the glass behind it, ou will get blisters. No voids, no blisters. My S2, which is nearly 30 years old now, ( 1980 Mocel ) has never had a basrrier coat applied, and last time it was hauled, 18 Months ago, there was not a single blister to be found. Troendle Marine in Pennsacola also does not recommend a barrier coat. He impressed me quite a bit with the quality of work his yard does, and his overall knowledge of boats in general.
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