Well I put my boat through quite a bit this year and have busted up a few rivets. There are more than one leaking, but they are all small enough that I can't tell exactly which ones it is. I've heard of ppl "melting" down rivets to fix them. Can this be done to all of them to help prevent future leaks like this?

epoxy - jb weld - or - alumaloy

http://www.alumaloy.net/

Never used it but looks promising for DIY repairs

Leaking rivets can be repaired. After you pinpoint which one(s) are leaking get a buddy to help you. The man in the boat will have to apply pressure with a heavy mall or hammer on the rivet, the other guy underneath the boat will have to tap moderately on the rivet with a ball-peen hammer. What you are trying to do is get the rivet to expand some more to fill the hole. You can also get some marine grade paint and paint over the leaking rivet after and that will help to seal it up.

why not just put a new rivet in?????

Have quite a bit of experience with this (until I got enough money and sense to get an all welded boat).

Have tried a number of things including JB weld, having them welded, and 5200 marine sealant.

Best is probably get them welded.
JB weld is great but isn't meant to flex so if you get any flex it will crack and start leaking again.
5200 (3m product-any walmart/lowes/home depot usually have) is some really good stuff. It is a mess to work with so be careful, but it is strong and will seal anything. If you can put inside the boat, it will be better, but that is hard with rivets. On the bottom of the boat it may wear over time (especially if you are running over stuff), but is easy and quick to reapply.

If you beat the rivet back out as suggested, you might want to put some 5200 afterwards as insurance.

Good luck. Been there, done that, got the t-shirt (and it has jb weld and 5200 stains all over it!)

i reseated the ones i had leaking. slid the boat off the trailer on some 2x4s
then placed a short piece of 2" x 1/4" flatbar under the rivet head. got inside with a flat punch and 4 lb hammer and went to work. the hard part was lining the flatbar up under the rivet. i did mine solo, would have been much easier with beer and a buddy to help.

So 5200 is better to use than jb weld?

Gluvit.

The 5200 is great. It is strong as hell, but flexible enough to give when the boat flexes. The jb will crack and fall off.