|
|
[pearson424] Blisters Inbox
pearson424 Jim Ashworth Sent on: Oct 31 There may have been email strings on this in the past, but if so, it was either "before my time", or I missed them. Have Pearsons been known to have blister problems? When I bought ketch #38 four years ago, the broker admitted blistering, but said it had been taken care of with the typical barrier coat process. I wish now that I had researched then. I put the boat in the water and brought it down via the Illinois River to Alton, IL....now four years later, I've hauled it out, and find extensive blistering. Some of what I read is very scientific and convincing, and concludes that it is a major concern to be dealt with carefully. Others say that it is really just superficial, and even after dealing with what's there now, it will probably come back, don't worry about it, it's not likely to become structural. My immediate concern is with a conflict between one writer who says to never begin by sandblasting (saying that it will create small craters which will become sites for even more extensive blistering the next time), and the boat yard which is very supportive of sandblasting (saying it's the best way to expose the current voids, and a good barrier coat after proper drying will do the job). Any experience out there from other P424 owners? Thanks!! Carter, Richard You've got a solid layup hull, not cored. In my opionion, if you leave the blisters alone and let them grow, you would eventually have structural problems. If you catch them while they are superficial, it won't hurt the laminate. I've heard mixed reviews about barrier coats. Apparently, it isn't helping your situation. Rich Carter Jim Ashworth Sent on: Oct 31 Thanks for your insight, Rich. I have a whole lot more than 50. The yard man says that many of them are "barrier coat blisters", meaning that the water either got through the previous barrier coat to form the blister, or the hull was not dry enough before coating and the blisters are from water trapped under the barrier coat. I can tell some are under the gel coat, and we may even find some in the first layer of mat (which is where most writers on the subject say they are most prevalent). We couldn't get to them right away, although the yard does say they want to expose them as soon as they can get to it....will probably be after the boat has been out a couple of weeks. My guess is the yard wants to sandblast in order to reveal the cavities formed by the blisters that are no longer obvious. Has anyone heard a caution against sandblasting? JTA Carter, Richard Sent on: Oct 31 Jim I've heard of sandblasting the bottom, but I understand it is tricky. If you get heavy-handed with the sandblaster, you'll tear the gelcoat off irregularly. There's also a process using a special machine that peals the gelcoat off. This has a great recommendation, but there are few yards that have the machine. Either above repair is probably very expensive. After I sold my old 30' sailboat many years ago, the new owner had problems with blistering. He sailed the boat to the Bahamas where he had it stripped and re-jelcoated. It was affordable to have it done there. Rich Carter dave jones Sent on: Oct 31 Hi Jim, Doris had blisters prior to our buying her and having them fixed was a condition of our purchase agreement. Our yard sandblasted, faired the entire hull and did six coats of barrier coat. I believe it was two primer and four final. Our original problem was relatively minor- I would say two to three hundred blisters none larger than a dime, most smaller than an eraser, and only a couple through the gel coat. This was done about ten years ago and we have seen no reoccurrence since. I would say that in our case sandblasting worked just fine. I think that the success of either technique- sandblasting or planing off the gel coat- is tremendously dependent on the skill of the operator. Probably the other most important factor is the thoroughness of the drying process prior to barrier coat application. I have seen boats peeled and if I knew that the operator was really good I would probably go with that method as fairing etc. afterwards would be easier, but to my mind those peelers can probably do a lot more damage in a shorter time than a sand blaster. Best of luck with your project. Dave Joseph Steiner Sandblasting opens up the blisters and a barrier coat may reduce the ability of water to penetrate the outer hull. But your problem will come back as most of the water has already penetrated the resin. Additionally, freeze thaw cycles in the North create huge blisters and eventual cracking or delamination. The best approach is to strip off the gel coat and refinish with epoxy, a polymer which is much more resistant to moisture. My "Half Moon" ( hull # 71 ) was done this way and sheis blister free since the repair was done 8 years ago. Best of luck, Joe, mary e. springhorn When I bought ketch #61 six years ago, she had "boat pox"....blisters too numerous to count. I'd dealt with blisters before, and my surveyor was the gentleman that did all the blister surveying for Valiant back then (Valiants were made here in Bellingham then.) Basically, I had the hull peeled and reglassed with a vinyl ester barrier coat. One the one hand, I'll never have the problem recur, but on the other hand, Pearsons of that era were so overbuilt, that it would take many more years of neglect for the blisters to become structurally important. I can't speak to sand blasting, but I've heard people tell of grinding them open and filling in the voids. Good luck! Mary E. Springhorn P.S. Due to osmotic issues, the blisters tend to worsen in FRESH water (rather conterintuitive, eh?) My boat lived in Portland for twenty years before I bought her. Rudy Janis Hi Jim; Not sure where this string actually started. Naked Moon, Hull 197, had several hundred or more blisters when we got her more then 10 years ago. At that time, she was peeled and coated with a West Epoxy Barrier coat. The peeling only took off the very top of the gel coat since the gel coat was very thick. None of the blisters were into the laminate. All were on the surface and just into the gel coat. The boat actually looked like it had two layers of gel coat. The boat was allowed to dry inside a heated shed over the winter before re-coating with the West System. The moisture level was monitored to see how dry it was becoming. It actually lost most of the moisture within the 1st month and then the drying rate decreased. The moisture was mostly stable when it was finally re-coated. Since then we have had a few blisters returning the past several years. Maybe 2-3 dozen and these are then opened up and allowed to dry and refilled with epoxy. I strongly recommend peeling versus sand blasting. Sand blasting is very subject to the operator experience and skill. I have seen where they have cut into the laminate when the operator was not careful. The peeling process is normally done by a company that specializes in that type work. They travel from yard to yard in an area doing this work. They set the blades to only cut a fixed depth and can make multiple cuts if it looks like they need to go deeper. They end up normally with a very smooth surface to re-coat versus a more uneven surface after blasting. I really am not sure their is a true cure to the blistering problem. It just takes continued follow-up. Good luck. Rudy Quent Kinderman A couple more thoughts on the blister issue. Clairebuoyant had the typical pox when we acquired her, about five years ago. Our fiberglass guy ground off the gelcoat, let her dry indoors a couple months, then added a couple layers of mat set in vinylester resin. She has been in the water at Chesapeake Bay for several years, and it will be interesting to see if she reblistered. Our surveyor said to expect it, but that's not a reason to get a new boat. A couple people have commented that Pearsons are overbuilt, but I think that if you remove much laminate, it is a good idea to replace it. We replaced all the through hull fittings with seacocks, which gave us a look at laminate thickness. Toward the keel, it is substantial, but at the turn of the bilge, at the port side, forward deck drain through hull, there was barely 1/4" of laminate thickness. Quent Kinderman, Clairebuoyant, #132 Joseph Steiner The concept of stripping the outer layer, letting the boat dry ( really dry ), is the correct approach if you want to permanantly fix blisters. A vinylester resin is good, at least it's better than a styrenated polyester, but epoxies are best. It seems to me to be worth the extra cost of epoxy when one spends so much stripping, drying and applying. IMHO, Carter, Richard Rich Carter Joseph Steiner If you haven't had blisters all these years you probably can sleep tight. You have a well made hull and you keep her maintained properly. Blisters usually show up within 20 years. Carter, Richard About half of the below-water glasswork was replaced because of the storm damage, so that might explain why I've been spared from blisters. Rich Carter |