There should be a plate of whatever material (silicon bronze?) imbedded in
the keel with threaded holes for the bolts. Maybe someone swapped the
original bolts for the ones that have caused the threads to corrode?
The "hard plaster" sounds like the areas was faired with resin and filler.
Probably the best way to fix this would be to dig the plate out and either
make a new one or re-tap the holes larger (use bolts that are of the same
material as the plate) and glass it back in.
MMC
"Jim and Becky" wrote in message
...
I own a 32' fiberglass lobsterboat with a full keel. Two of the bolts that
hold the rudder plate to the skeg are loose as they spin on themselves.
They
do not have nuts on them. They just screw into the skeg.
What is the keel made of? It is about 4"x4". Its white and when scratched
looks like a hard plaster. Pure resin would seem too brittle. Maybe a mix
of
resin and chopped fiberglass or strands laid into the mold?
I'm thinking about drilling right through it top to bottom then using long
stainless machine screws and nuts.