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Old 11-12-2015, 07:24 PM   #1
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Blisters? No Problem!

Well many of us here have talked about blisters, some of us have repaired blisters, and most all of us live in fear of finding them on our bottoms. Would you let blisters stand in the way of buying an older used boat ? Well after reading this guys article I must say it's a different viewpoint. Check it out and tell us what you think...

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Old 11-12-2015, 07:43 PM   #2
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Thanks...that was an entertaining and informative article
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Old 11-12-2015, 08:21 PM   #3
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Great article, thank you for posting the link.

What I know about fiberglass chemistry and technology wouldn't cover the head of a pin. But over the years I have heard from people I've met in the boating industry who I consider to be very credible that while blisters can certainly be unsightly and can have an effect on a boat's efficiency through the water they are not structurally dangerous.

Some of the points in the article are well worth remembering, I think. One is not to damage/sand/grind the gelcoat on the bottom of a boat. Another is not to remove any laminate when redoing a boat's bottom.
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Old 11-12-2015, 08:53 PM   #4
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#1 applied to Uniflite's post 1974 production. If you are in the market for a nice sport fisher then you can get a great deal because of the blister issue although it might look like hell.
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Old 11-12-2015, 08:53 PM   #5
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Yeah, I've had a few surveyors (and a bunch of brokers) tell me that they have never seen a boat sink from blisters. They don't seem to kill a boat sale like they did 10 or 15 years ago.

Interesting that what once once viewed as a HUGE issue is becoming less so. That never seems to happen with boats.
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Old 11-12-2015, 08:54 PM   #6
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Very informative article. He made a believer out of me. I spent about $13-14k grinding down a hull on a 43' Taiwanese aft cabin shortly after I purchased her. I had gotten a reduction in the price to cover it. Hard not to listen to the horror stories that the fiberglass hull will delaminate if the blisters are not addressed. I also heard the bit about the boat absorbing water. Problem is that if you buy a boat with blisters and address them as they come up, you are going to lose on resale. I may be convinced, but that doesn't mean that the issue won't be used as leverage on sale.
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Old 11-12-2015, 09:46 PM   #7
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Not sure I'm convinced. In the early days of solid thick non cored hulls, I would accept that surface blisters are not a structural problem. As hull thickness became thinner and thinner with more state or the art glassing technique, I'm not sure that one should necessarily disregard blistering. Also, the author talks about the fiberglass or more correctly the hull absorbing water. Whenever I have heard that term, it relates to coring material (especially balsa core) having become saturated, and yes the hull becomes heavier as a result. If I had a cored hull (I have 2 cored hull boats), I would be very concerned with blistering and the increased risk of saturating the coring material. In conclusion I believe that risk from blistering depends significantly on the composition of the particular hull.

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Old 11-12-2015, 09:48 PM   #8
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Not sure how grinding out delaminated roving and properly repairing it weakens the hull....there are others....NAs, surveyors and yards out there with plenty of experience that would disagree with the author.

I did my homework before repairing my boat and discussed it with some of these others as well as extensive reading/research.
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Old 11-12-2015, 10:16 PM   #9
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I am old school, and not a believer. The only way to find see if a blister is gelcoat or deeper in to the laminate is to break it. If the blister is really surface gelcoat it is simple to break the blisters, apply a epoxy filler, and apply bottom paint. Not hard to do or expensive. So a blistes should be evaluated.
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Old 11-12-2015, 10:27 PM   #10
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What's worse? Steel with rust or fiberglass with blisters and corrupted cores?

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Old 11-13-2015, 12:34 AM   #11
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That Fiberglass "Blister" article represents another of the important reasons I own a built to last 1977 Tollycraft tri cabin pleasure boat!

With well laid FRP, up to 1.25" thick hull, and no wood or other filler material in her hull... that includes, transom, bow, short keel, and super strong stringers.

Happy Anti-Blister Daze! - Art
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Old 11-13-2015, 12:53 AM   #12
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David Pasco is another well known surveyor that has extensively covered the topic on his web page and essentially agrees with this article. If your interested in coring, Pasco covers the topic well.
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Old 11-13-2015, 05:29 AM   #13
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I agree, most blisters are in the gelcoat and not necessarily a precursor to blisters in the laminate or hydrolysis (disolving resin) however ....... there are exceptions where blisters in the laminate can be seriously expensive and astructural threat. Take a look at Psneelds photos in this old thread
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Old 11-13-2015, 07:17 AM   #14
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Quote:
Originally Posted by boatpoker View Post
I agree, most blisters are in the gelcoat and not necessarily a precursor to blisters in the laminate or hydrolysis (disolving resin) however ....... there are exceptions where blisters in the laminate can be seriously expensive and astructural threat. Take a look at Psneelds photos in this old thread
Thank you !

Most boats aren't a big problem....maybe thousands to one...so seeing thousands of bottoms don't mean you have seen it all.

I will bet the author would have scratched his head as he saw me easily peel away 1/4 inch thick pieces of laminate roving by hand that were several feet long.

Again...you may not even know you have this sort of issue if you take this guy's advice.

Read up, study up and follow up. Or casually ignore as most advise.

Oh and PS... a well known, highly respected surveyor missed my hydrolysis/delamination issues.
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Old 11-13-2015, 07:28 AM   #15
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"What's worse? Steel with rust or fiberglass with blisters and corrupted cores?"

Steel can be maintained with a monkey with a wire brush and a paint pot.

GRP should require no repair if its a solid lay up or a properly selected/installed core.

The hassle is a tiny scratch on the tin boat must be instantly repaired (just as on a woodie).

A scratch or deck leak on a GRP boat is of no structural concern ,

only weather its over your bunk, or will task the bilge pumps too hard.
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Old 11-13-2015, 07:48 AM   #16
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Art, I guess your Tolly is one of the exceptions, I talked with the technician that had been stripping gel coat for 14 years and he said he'd done them all, Hinkley's, Nordeys, blue plate to cloroxe bottles, they all get blisters the only difference was to what degree.
Seems as I recall from a Boiler Feed Water school that what ever is in contact with water will be dissolved by it eventually.
So to those of us with blisters, enjoy it's natural occurrence and state of being.
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Old 11-13-2015, 07:57 AM   #17
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Quote:
Originally Posted by psneeld View Post
Oh and PS... a well known, highly respected surveyor missed my hydrolysis/delamination issues.
Out of a few hundred surveyors that I know there are several well known, highly respected surveyors that I personally would not hire and a few (very) little known surveyors that I trust implicitly. I feel for anyone trying to choose the right surveyor.
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Old 11-13-2015, 08:34 AM   #18
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Originally Posted by boatpoker View Post
Out of a few hundred surveyors that I know there are several well known, highly respected surveyors that I personally would not hire and a few (very) little known surveyors that I trust implicitly. I feel for anyone trying to choose the right surveyor.
Better you said that than me.....

My point was to head off all the Monday morning quaterbacks if they are done over on the accident threads....
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Old 11-13-2015, 10:04 AM   #19
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My take on the article which I believe is largely the consensus of everyone except those selling blister repair jobs is: Blisters are an aesthetic issue, nothing more, nothing less.

He did address the issue of delamination but makes the point that blisters and delamination, are two entirely different issues. Blisters "do not cause" delamination, but "delamination" can result in blisters. As he states, ineffective bonding of resin to the glass cloth during layup causes delamination. This is a very important distinction because as we well know, the industry uses delamination fears to sell blister repair jobs.

In my opinion, Scott's delamination pics seem to support the authors findings. Did his resin from "so deep within" the laminate and over such a large area simply wash out due to blisters, or was the resin never there in the first place. Could also be poor layup technique or ineffective bonding of the resin. It is a great point however, that had he not attacked the blisters, he may not have discovered the serious delamination issue.

One thing that has bothered me about blisters however was whether or not it was better to pop them or leave them alone. I have asked many, including here on TF but no one seemed to know. I was pleased to see the author addressed this and While he makes it clear he is only rationalizing, it makes sense: (quote) Remember that in order for the chemical reaction to take place, the water has to have been trapped under the gelcoat for some time without circulation. It therefore follows that if the blisters are punctured at an early stage, before they have been able to cause any damage, there will be circulation, thus, the acid will not form or get to a stage where it can be harmful.

Being the skeptic that I am, I can't help but think if simply popping them early eliminates the problem, why hasn't someone else thought of this.
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Old 11-13-2015, 03:28 PM   #20
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For all you'z guyz that think your "solid" fiberglass hulls are immune to blisters keep in mind that the uniflight hulls were also solid. Actually solid frp is more prone to blisters than sandwitch cored hulls. A 1 inch thick solid frp hull takes much more expertise to lay up properly. Expertise was and still is missing from most boat hull manufacturers. Most companies now are using vacuum bagging procedures. This takes most of the guess work and "expertise" out of it. Basically, some boats blister from permiable gell coat, some boats from dry laminates. Typicall gell coat blisters, even those extending into the laminate, are unsightly but not structural issues. Dry laminates are a whole different issue, and potential huge can of worms. As an aside, years back on this or the other "trawler" forum someone posted his way of dealing with blisters. He drilled a hole in the top and bottom of the blister and flushed it with acetone (IIRC). then with a syringe he filled it with epoxy from the bottom up until it ran out of the top hole. He then plugged the bottom hole and let it set up. He later sanded the "bump" smooth and flush then painted with epoxy primer. Then bottom paint. Apparently it worked for him, and I've used the procedure several times with good results. YMMV.
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