Lots of fantastic advice, and I'll be reading through again just for the education.
However, wrt the problem, colemj nailed it. I drilled the holes just as UNCIVILIZED suggested, installed a tube and attempted to find and suck water. No core
at the screw holes, and no water in the section either. Whatever was dripping out of the screw holes dried up during the arid summer in the Virgin Gorda Yacht Harbour Boatyard.
As there was no water deep in the hull
that is lower than the screwholes (at least 20 inches forward of the transom), and as there had been no real venting until I had drilled the exploratory holes, I have to conclude I cannot have much of a problem.
I epoxied the holes, gave a layer of epoxy paint
over the area where gelcoat
had cracked or fallen off, and reinstalled the rubber with 4200 and new screws.
Interestingly, when I first acquired the boat out of charter
, the plenum under the engines on both sides were filled with pressurized water. The charterer had drilled screwholes into the plenum area from under the boat to fasten solid covers over the saildrive
boots, and obviously messed up. I found it by trying to replace engine
mounts while afloat, and scratched my head
for days over it.
Thanks folks for the education and advice.