On Thu, 09 Jun 2005 19:17:13 -0400, Chris wrote:
[I have rearranged the order so that it flows chronologically]
wrote in message
ups.com...
It's too late to do any more than slightly slow the problem by sealing
the exposed wooden surfaces of the drain hole.
If you like this boat and plan to keep it, you will want to cut the rot
out of the transom. Be sure to go a few inches beyond the point where
you "think" the rot ends when scarfing in the new piece. You should be
able to cut away part of the fiberglass on the outside of the transom
and spoon out the punky wood, cut a new piece of the best marine ply
you can find, and then glass up the exterior again.
This is a great chance to learn from the bad practice of the original
builder. Any hole drilled through a wooden member- transom, stringer,
etc for the purpose of draining water should have the edges sealed up
to prevent water from wicking into the surrounding area and promoting
rot. If it were my project, I would cut the drain hole large enough to
accept a drain plug with a bronze collar fitting. Seal the edges of the
hole with a layer of glass and resin, and then bond the bronze collar
into the sealed hole- perhaps using epoxy.
One rot gets a foothold, it is relentless. Transom rot on small boats
is fairly common, and as most are outboard powered it is double
trouble.
So replacing wood with new plywood means I can cut out a shape of any
size and replace it with a close to equal piece of plywood correct?
Just glass the old plywood to the new plywood, right? No concern over
how big a piece of plywood is, etc? I could use two pieces of plywood
for one hole? etc
It appears I've got more rot than I had expected (although the transom
feels strong otherwise).
I've pulled out about a 1 foot x 1 foot section around the drain plug
and am evaluating whether there will be anymore to go too.. Have drilled
a bunch of holes in the lower inner part of the transom to see how far
it spreads and allow all the wood to dry up before my final decision
I didn't see the original thread. If it is a fiberglass boat with a
plywood core, then you are probably right. You can probably get away
with putting in a whole bunch of plywood more or less however you want,
But don't leave any voids, and take steps to ensure that the new plywood
is bonded to the adjacent old plywood. You may have to use some kind of
adhesive filler for this. Epoxy, with filler, for example.
On the other hand, if it is a plywood boat with a thin layer of
protective glass, or glass on only the outside, then you are probably
wrong. In that case you will probably need to scarf in the plywood very
carefully.
I'm not an expert, so take my advice with a grain of salt. But the whole
idea behind sandwich construction is that the core experiences mostly
compression loading, and the skin experiences mostly tension.
Of course, this means that you have to do a good job tapering the
fiberglass thickness where you meld old glass with new glass. I think I
have seen a 12:1 ratio recommended. That is, if the glass is 1/8" thick,
you would taper over 1-1/2".
--Mac
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