On Thu, 09 Sep 2004 20:42:04 +0300, kim wrote:

It leaks significantly only after being sailed hard to
windward.

It's trying to tell you not to do that. :-)

Mast is keel stepped, and leakage occurs when tiny gaps open
between the first plank and keelson near the mast step. I was thinking that
maybe building a stainless steel frame connecting chainplates, keelson,
keel bolts and mast step would reinforce the setup enough for keeping the
planks together and allow for shrouds to be tightened more?

Is it possible you've got too much rig tension? You can not set up
the rigging bar tight on an old wooden boat without stressing it out.

I'm not a wooden boat expert nor do I play one on the internet. I've
read enough of these discussions in the past however to know that
there are almost never any quick and easy solutions. It's almost a
certainty that the boat did not leak like that when it was new, so the
real question is, what has changed? Common problems are loose
fasteners, cracked ribs, spongy planks, and/or a need for re-caulking.
If the boat is worth saving at all, it's worth having an expert look
it over and figure out which of the above is applicable, if any.
There is a newsgroup called "rec.boats.building" which has a fair
number of wooden boat experts. I'd recomend reposting your question
there but you also need to find some local talent.