On Wed, 15 Apr 2009 21:28:56 -0400, jeff wrote:

Last fall I drilled several small holes, about 1/4 inch, into the
hollow, sacrificial keels of my cat. I was exploring for water which
has been known to get into the keels, but found none.

Now I have to patch the holes. I know I have grind them out a bit, and
take the paint off nearby, but I wondering if anyone has a suggestion as
to the best way to seal the holes: epoxy, polyester, or something else.
I think they're too small to bother with glass, but its not out of the
question.

BTW, one of the sisterships that did find water epoxied in air
compressor nozzles so that keels could be pressurized to find the leaks,
which were at the seam with the main hulls. The nozzles were then
replaced with drain plugs. Since I had no intrusion, I don't need to
get that fancy.

If it were my boat I would sand an area around the holes back to the
glass. Then I'd countersinking each hole and fill it with epoxy resin
thickened with something to make a filler. Finally I'd epoxy a patch
of glass cloth over the holes. While there is no reason not to fix a
polyester hull using polyester I'm a real fan of epoxy for repairs.

I don't think that all this is absolutely necessary but I like belts
and braces and if it is really, really fixed you can forget it.

I would be pretty skeptical of pressurizing any composite structure as
it takes surprising little pressure to burst something not designed as
a pressure vessel. I've seen fiberglass water tank sides bulging from
the weight of the water in the tank.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)