On 30 Sep 2005 20:29:30 -0700, "bob" wrote:

Are you talking about bedding chainplates on the outside of a hull or
sealing where they pass through a deck?

Excellent question.......... plates measure 1/2"x 2 1/2"x 20" and pass
through deck. Deck is cored: 1/4" glass, 3/4" end grain balsa, 1/4"
glass.

Plan on digging core out and potting with thickended epoxy. But still
confused about the next step: 5200 or ? to fill 1/4" gap between plate
and epoxy.


For bedding I'd use eg 5200, mold release wax and some sort of spacers
to create a gasket, then seal the gasket and bolts holes/threads with
a sticky non setting compound.

Hummm. I like the sound of that.
The above is for plates bolted to a hull?
So suggestions for plates through deck?

Maybe something more flexible like Sikaflex 221/291 or equivalent
would be better than 5200.

For best leak proofing I'd use a 1/4" deep seam of 22l on the bottom,
then some round section 5/16" closed cell foam wound round the chain
plate combined with a generous amount of sticky butyl sealant, then
another 1/4 seam of 221 on the top.

Would be a little tricky, probably best to mask the top 1/4 of the
gap, put some foam in, do the bottom and wait for it to set, then add
more foam and non setting goo, pull the masking tape away and do the
top.

Still it would give 3 layers of sealing, even if the 221 failed in
part it would keep the other stuff in place nicely. Even if it did
need redoing in some remote place, it should be easy to cut through
the top and reuse the foam with more goo.

I'd expect most problems occur where something is used to bed stuff
which is then tightened down too much initially, leaving a layer that
is too thin to take any movement and cannot be compressed further.

Agreed. This is exactly what I have found with all other through deck
bolts. Big problem.

If making a gasket as above I'd use washers round the bolts as
spacers, then when they are removed I'd fill the hole with some non
setting sealant so it forms a nice donut round the bolt thread.

cheers,
Pete.