Blistering left unchecked? - SailNet Community
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post #1 of 5 Old 03-15-2019 Thread Starter
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Blistering left unchecked?

Was talking to the guys working on the boat next to me in the yard. They're nearing the end of an extensive blister repair project, he said the blisters were so numerous that they just ground 1/16" off the entire hull and built glass layers back up because grinding the blisters individually would have taken too long!

It got me thinking. We all know that blisters are bad. That you should avoid buying a boat with blisters. That if you have them you need to grind them out and fix them, etc, etc ...

But what happens if you just ignore them? I assume they'll just keep getting worse, but how bad can they get? Will they eventually get so bad that they compromise the hull and cause leaks? Can they outright sink a boat? Has anyone ever seen them get this bad?

Just curious ...
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post #2 of 5 Old 03-15-2019
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Re: Blistering left unchecked?

I dont think blisters get worse. I am told they are caused by voids in the fiberglass layup. Once they show up I think they all show up, and once they are ground out and filled the problem is solved. I had quite a few on one of my boats, and when I ground them out each blister was full of water.after they were repaired the problem never came back.

I have a friend that had a boat that had hundreds of little blisters, and like the boat you saw it was easier to grind the whole hull down rather than spot repair. That was a race boat, so we hauled her regularly for sanding and paint. We would never have ignored blisters and let them accumulate. They definitely appeared all around the same time. Once the repair was done they never came back.

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post #3 of 5 Old 03-16-2019
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Re: Blistering left unchecked?

I read alot about it a couple of years ago, and was only able to track down one single hull, that was structurally compromised due to blisters.
The reason given, was that the used types of mats in the layup was completely wrong.
As I understood it at the time, on a correctly build boat, it can never get deeper than the first couple of layers after the gelcoat.

My slip neighbour has a boat from the early 80'es and it is really really bad with blisters. When they remove the gelcoat, you can see glass completely void of any resin. But they are never more than 1-2 mm deep. So I think they have stopped fighting it, and they sail A LOT.
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post #4 of 5 Old 03-16-2019
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Re: Blistering left unchecked?

I also had a friend who had his 49 ft Taswell stripped clean and a new vinylester skin applied. I'm not sure there is good science around how to determine impact on hull integrity. I bet each is a bit different and that's the rub. Most don't want to be offshore, with that nagging question in the back of their minds. Warm water lake sailing would be a much lower concern.

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post #5 of 5 Old 03-16-2019
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Re: Blistering left unchecked?

Aren't blisters like the dimples on golf balls? They help with the aerodynamics and increase speed?

I was recently looking at a Valiant 40 and they had blister problems during certain years of production due to a flame retardant ingredient added to the layup, based on the company building the boat had military contracts requiring such. Adding to the consensus here, my research showed, once repaired by grinding off layers of gelcoat and glass and building back up then I believe an epoxy barrier the problem is solved. From what I read the type of blisters associated with the Valiant was a cosmetic issue only.

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