May 17, 2016

Are blisters over-rated?

“SHOULD I BUY a boat with blisters?” That’s the query I once received from a reader in San Diego. “Cautious” had fallen in love with a 10-year old, 30-foot sloop, but he was scared to tie the knot. He was afraid to commit, because when he had her surveyed he found she had “a whole lot of dime-sized blisters on her bottom.”

Well, my advice to “Cautious” was simply: Grit your teeth and buy her. Nobody’s perfect, and no boat is either. Although fiberglass boats have been around for more than 50 years, there’s still a lot of misinformation doing the rounds, especially regarding the dreaded boat pox.

It’s reassuring, therefore, to hear the experience of David Pascoe, a marine surveyor based in Destin, Fla., who says that in more than 30 years of surveying and examining 4,000 hulls, he has seen fewer than 10 cases where blisters have resulted in serious structural degradation of a hull.[1]

We’re talking here of dime-sized blisters. In 99 percent of the boats Pascoe has surveyed, blistering involved only the gel coat and the surface mat — neither of which is a structural part of the hull laminate.

Pascoe says that even boats with numerous blisters up to about 1-inch in diameter usually show no significant weakening of the plastic. As a result, “moderate blistering on an older boat rarely impedes the sale.”

As a matter of fact, Pascoe reckons that by the time a boat is 8 or 10 years old, “whatever is going to happen to the hull has probably already happened.” That means if she hasn’t developed blisters yet, she’s not ever likely to, so don’t be tempted to apply a barrier coat.

It’s quite another matter if a new boat develops blisters, of course. On a boat that’s been afloat for only two or three years, it’s likely that blistering is just the beginning. That’s not good news. But one that’s been afloat for eight years or more without developing blisters is  pretty safe bet.

Interestingly, Pascoe doesn’t even think it’s necessary to do anything about small blisters. Admittedly, they make the hull more difficult to paint and they will slow the boat down slightly, but: “If blisters cannot be shown to be causing significant damage, then repair is certainly not mandatory, despite the many horror stories you may hear from people trying to sell you a costly repair job ... Bear in mind that blister repair jobs are now big business for boat yards, so that taking advice from yard managers may not be a good idea.”

He makes another good point, too: “Further, you should be aware that the number of failed blister repair jobs that surveyors find is very high. No one’s ever going to know why blister repairs fail because no one is going to spend the money to find out.”

So go ahead, I told “Cautious.” Be brave. Put your money where your heart is. Who else is going to see your new girl-friend’s bottom anyhow?

Today’s Thought
The desire of perfection is the worst disease that ever afflicted the human mind.
— Fontanes, Address to Napoleon, on behalf of the French Senate, 1804

”Why do you call it love at second sight?”
“I didn’t know she was rich when I first saw her.”

(Drop by every Monday, Wednesday, Friday for another  Mainly about Boats column.)

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