I'll have to wait and see your pix. Best of my knowledge, tin boats didn't get a putty along the deck between the deck and hull sides and can you be more specific about what you're seeing that suggests something was attached to the tops of the ribs? Evidence of a screw/rivet hole.
I've not seen a Bel Mara before, so not sure what that putty might be if factory (I suspect a previous owner did that)
Did it come w/ the original deck in place, if only in pieces? Or does it appear like a previous owner put in a new deck? Did other work too?
I prefer pix option 3, and use Photobucket as my 3rd party host sight. There are other 3rd party sites