A few years back I decided to take
all the old bottom paint off my 1983 Cape Dory 27. It consisted of numerous layers of hard epoxy
anti-fouling and I had the impression that this job had never been tackled
before.
I had a shoulder injury at the time,
but I hauled her out and started removing the old paint in small sections,
about 5 feet by 2 feet every day. I used
a chemical stripper and a hand scraper. It took me several weeks of hard labor
to get down to the gel coat all over.
Then I washed the whole hull down
carefully and applied Interlux’s Interprotect barrier coat system, following
the instructions to the letter. I did
alternate coats of white and grey epoxy and then I painted the bottom with two
coats of Interlux Ultra antifouling.
It all looked very splendid and I
was pleased that I had taken the extra trouble to put on a barrier coat, having
taken all the old paint off anyway.
But two years later, when I had the
boat hauled out for repainting, the bottom was covered with hundreds of small
blisters under the barrier coat. I could
have cried. A marine surveyor who looked at it for me just laughed. It wasn’t a structural problem, he said, just
cosmetic. He advised me to sand right
down to gel coat again.
“What made you apply a barrier coat?”
he asked.
“I just thought it was a good
idea. Having done all the hard work to
get the old paint off, it seemed like an ideal opportunity to protect against
blisters.”
“Did you have any blisters before?”
he asked.
“No,” I said.
“So she has spent more than 20 years
in the water without forming any blisters,” he pointed out. “What made you think she would suddenly get
blisters now?”
“Advertising,” I said. “The adverts say it’s a good idea.”
After a while, we both had a little
chuckle at that.
The lesson I learned is that the
fiberglass hull must be absolutely dust-dry before you can apply a barrier
coat. I don’t mean just surface
dry. It has to dry out for months. If there’s the slightest suspicion of any
moisture trapped in the fiberglass it will simply form blisters beneath the
barrier coat.
Since then, I have read about many others
experiencing the same problem. “It seems
the marine industry is always trying to sell us something,” said one boat
owner. “For some boats, a properly
applied barrier coat might be beneficial.
As for the vast majority of boats, I would say if it ain’t broke, don’t
fix it. I never imagined the prevention
I thought I was providing would become the problem.”
I regret to say I know exactly how
he feels.
Today’s
Thought
Any
man may make a mistake; none but a fool will persist in it.
— Cicero, Philippicae
Tailpiece
“Did you buy that new book on schizophrenia?”“Not yet. I’m in two minds about it.”
(Drop by every Monday, Wednesday,
Friday for a new Mainly about Boats column.)
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