Posted by katorpus (katorpus@…>)
— In freedomyachts2003@yahoogroups.com, Chuck Bates <c3g2b3@d…>
wrote:
I have Freedom 33 CK #58. She has developed blisters in the
topsides on
the port side of the boat.
Has anyone any experience with topside blisters? I’d like to know
what
the cause is, so I can determine a repair technique that will
last.
Chuck Bates
Chuck
My F40 AC (Hull 61) has significant blistering above the water line
on the port side stern quarter. When I bought the boat, I also had
major blistering below the waterline. Everything above the waterline
showed bone dry on the moisture meter from day one. I didn’t open
any of the blisters above the waterline. There’s really NO place for
water intrusion to have occurred other than the rub rail attachment
screws. My stanchions are all attached only to the toe rail. My
pushpit is through bolted in the deck. These blisters are apparent
only below the rub rail and extend forward only to the bulkhead
separating the port lazarette from the aft cabin. I removed some of
the paint on the inside of the lazarette which permitted “seeing”
the core through the final layers of glass & mat. There was
no “darkening” or evidence of water intrusion into the core.
There was significant water intrusion into the MAT layers below the
waterline, but I never saw any evidence that any of it got into the
core (even in the last places to drain/dry in the 6 month process of
drying out the boat).
My repair consisted of grinding off everything below the waterline
down to the first layer of mat, then regular (at least weekly) steam
cleaning to heat up the hull and drive out the water (assisted by
summertime Texas Gulf Coast temperatures). It took 6 months to get
things dry. As the “glycol mess” continued to from the outer mat
layer, it left behind “dry mat” spots (no remaining resin) in
numerous areas. These were ground out down to solid glass. In no
case did this require grinding BEYOND the outer mat layer. The glass
below that was solid, the core was dry. (The wettest part of the
boat was the “barn door rudder” which POURED water (for days) out of
the core after we drilled holes “high and low”. If I had it to do
over again, the whole repair would have been a lot faster if
we’d “kept on grinding” when we got to the first mat layer, but we
really didn’t know at that point whether or not the core was wet,
and I sure didn’t want to grind off everything down to the balsa and
build it back up.
We spot-filled the ground out areas with pieces of mat & resin, then
applied a complete mat layer on top of that and finished off with
vinylester (5 layers) epoxy and reapplied bottom paint. That was 7
years ago and there is no evidence of further blistering below the
waterline. The end result is, below the waterline, I have one more
mat layer between the core and the water than “anybody else” (and no
gelcoat).
The conclusion of all involved is that there was a problem with the
mix in the first layer applied to the gelcoat in the molding
process. Maybe the mat was contaminated, maybe the mix wasn’t right,
but the breakdown that occurred probably BEGAN internally (as
opposed to water intrusion)and the resulting failure of the gelcoat
in the blistered areas permitted the water to intrude and further
exacerbate the problem. Lots of the (particularly deeper) blisters
were a really nasty gunky thick mess that was highly “chemical” as
opposed to “watery”. It really appeared to be uncatalyzed resin.
The very existence of the same type of blistering in areas ABOVE the
water line would bear out this conclusion, particularly since they
are highly localized.
Your options for repair are fairly limited. If your hull is in need
of paint, then grind them out, fill them back in, fair the repair
and paint. My hull still has good gelcoat (after 24 years) and I
don’t plan on doing anything about the topsides blisters until I’m
ready to repaint the whole hull.
They aren’t getting “worse”. I don’t think they’re structural, and
they haven’t resulted in any apparent cracking of the overlying
gelcoat (Yet).