I have 6 or 7 rivets on my aluminum boat that are starting to leak. They aren't very bad. I filled the boat with water and after 30 minutes only one of them seemed leaky enough to actually cause a drip. The others just had water around them. Is there a good spray on sealant or anything like that that I can put on it to stop the leak? I'm looking to seal them up a bit better before I put a new coat of paint on it.