Some additional information: The Ferro-cement sheathing is almost a
1/2 inch thick, and strong. A couple of years ago I had a small
accident with a boat made from steal, he had to go to a reparation
dock. The deck and it's timbers are 15 years ago renewed. But its made
from pine, and it's not watertight. The water comes through the deck,
so it is fresh water , when we sail there is coming some salt water as
well but it's not the majority. The wood under the deck is old, there
has always been water in the bilge, there is a lot of rot wood, the
ventilation is difficult, I live in a humid country. Anyway the wood
is soaked.
But the boat as it is, still is strong. The old wooden hull in its
total functions as a part of the bone structure for the ship. The mast
rigging is still good, the shaft and propeller etc are renewed last
year(the old shaft was leaking water, we are trying to improve), the
steering system we are checking at the moment. Basically with the rest
we can live.
To keep it that way I have to do something with the rotten wood. I
think when I can stop the process of rot, I can try to get the boat
dryer and then I can try to improve the old wood structure with an
impregnating epoxy or polyurethane product.
Salt bags under the deck sounds like a smart thing.

Gerdjan van der Lugt