Piece of history there. Somehow I doubt there is any low-cost way of
dealing with this.

Some thoughts you may have dealt with already, but here goes:

Dumb question: Why is it so wet down there if the hull has been
encapsulated with ferro? Is it from topside? Has the water got to the
steel keel in the ferro and totaled it?

Thought: Salt water greatly inhibits rot (but kills anything it reaches
inside the ferro). Is that fresh or salt water getting into there? I'd
guess theres a lot of fresh water getting down there from topside. I've
heard skippers used to hang salt bags up under the deck at the sheer to
help keep the boat "salted".

Thought: The hull can probably be made tight by coating or encapsulating
the ferro. Penetrations would need to be handled carefully and
monitored, but that's doable.

However, 2nd dumb question: What _is_ sound on the boat? IOW, what's
worth saving, relative to the cost of saving it? Eg. by removing the
ferro (maybe not necessary?) and encapsulating in _structural_ GRP you
can manufacture a complete and dry structural hull around the existing
boat (I'm assuming that the ferro is/was not structural except at the
keel - it does not support the hull). By mickey mousing in somewhat
similar hi-tec fashion with the topsides and deck, you can come real
close to making her totally dry at the cost of a moderate weight penalty
and some clever deck modifications to handle rain water. At that point,
you would prep and then spray paint on all bilge/floor/hull surfaces
(interior) to further stop moisture absorbtion. The deck would probably
be the most difficult part. Now, what do you have? Is the interior good?
Is the mast/rigging good? Is the steering good? The boat would no longer
smell or sound like the wooden sailboat she began as. That's not to say
she'd be unpleasant or bad, but a totally dry boat with a very stiff
solid hull would be a quite different boat from the way (I think) she is
now. Would that be good for you?

Allan H. Vaitses (note spelling), of Mattapoisett MA, has made a name
for himself as an extremely practical and resourceful boatbuilder for
many years. He is now 85 or so and working on another book. He (and now
his son) has used encapsulation techniques for years to keep the local
fishermen going. If you contact him or his yard you may be able to get
another perspective on your problem. For purposes of amity, note that he
is a far right wing libertarian sort.

Rufus