I can't answer your question directly but have a suggestion for
installing the new boards when you buy or make them. I noticed in my
boat that water was getting into the wood stringers through the holes
for the screws that secure the floorboards. I made the holes in the
stringers about twice as large by drilling them out, filled the holes
with epoxy, then drilled new holes only in the epoxy. I then inserted
threaded brass anchors into the holes in the epoxy and secured the
floorboards with flat-head brass bolts. This system is great because
it not only protects the stringers from rotting but makes it very
easy to get the floorboards on and off without wrecking the wood
stringers. Good luck.
Doug Poland
#99 - Surrender Dorothy