Originally Posted by bowtie guy
OK will do. I will post back with findings...what exactly am I looking for?
You're making this harder than it should be.
Get up under the rub rail with a gun loaded with silicon caulking. Cut a small portion of the tip off and look for any place you can get that tip and squirt it full. Run up each side and all around looking for a crack or crevice you can fill... wipe off any excess and let it set overnight. Done deal.
I've seen this issue on many of the older boats and that has always been my remedy. The only way I'd pull the rub rail (too many rivets) is if I were going to split the deck from the hull or was going to replace the rail and the filler. Otherwise, it's as sound as it will ever be, you just need to fill a few open places.