I had a problem with the engine mounts on my boat. When I attempte to tighten
them, the bolts spun. What happened is that when the boat was outfitted,
they didn' caulk the holes. Moisture went from the mounts to the stringer
and the rot propagated 15 ft. down the length of the stringer. It's like
a bacteria that eats up the wood. My floorboards also had a similar problem
(no caulking).

The solution was to pull up the floorboards and to strip the stringer
out. I had it done by a professional boat builder. The total cost was
about 7.5K to do the job. Essentially, every piece of wood was removed
and reglassed in to the hull. Not fun to do on your own and a friend
of mine did it. I saw what it involved and decided to throw money at
the problem instead (his material cost was about 1.5K and about 70 hours of
labor).

b.