[aflanigan]

Wow, bad luck. Galvanic coupling is definitely something to keep in mind particularly if you are planning on keeping your boat long term.

Here''s a starting place; C25/250 owners forum on this very topic.

http://www.catalina25-250.org/forum/topic.asp?TOPIC_ID=4761

Looks like one alternative to trying to take out rusty old bolts is to "sister" them by simply adding new ones along side the old rusties. Good luck!

Allen Flanigan