If you don't know, I have an aluminum 18' cc that leaks pretty badly. It was coated with epoxy, and there are several loose or missing rivets. <br /><br />I've finished cleaning off the epoxy from the hull, and am trying to find the size pop rivets I need. I tried cleaning out one of the holes of the missing rivets, and found a rubbet-like substance behind it. I don't know exactly what this stuff is, but it looks like a white rubber block inside the hull. Could it be some kind of flotation? Is it allright to just start putting pop rivets into place with this stuff there?<br /><br />The further I get with this project, the more and more I keep thinking that I should just tear the whole boat apart and start from scratch.