My father has a 12’ aluminum boat that he bought from sears in 1968. Over the years we would periodically “tighten” the rivets to stop leaking. A couple years ago he coated the outside with flexseal, that stopped the leaks. He needs to reapply this year as dragging the boat up on shore has worn the coating away. When he initially told me his plan I chuckled and said “good luck with that”!