I pulled the rotten wood decking out of my jon boat, which I recently
purchased, and noticed that the 3 center supports are chacked through
the middle. Someone put 2 pieces of aluminum channel across the
cracked areas and attached them with rivits. They look like the same
rivets that were used to anchor the wood decking so I'm assuming it was
the guy who built the boat out.

What can I do to repair this and the loose rivets in the bottom?

Thanks in advance for your advice.

Garcam