I just purchased a 1986 Alumacraft Voyageur 17 canoe that has a missing rivet and water is pouring out the bottom of the canoe when I filled to check for leaks. Any suggestions on the best way to repair this? The hole that I assume is from a rivet is directly under one of the ribs. There seems to be another piece of metal over the hole. I guess I assumed the rib was hollow. Any suggestions or has anyone done a repair like this? Drill out and put in new rivet (although I am worried about drilling into and thru the rib)? JB Weld? Thanks for any suggestions or help.

Most any welding shop can just fill it in with some aluminum rod. I had an aluminum fishing boat come off my lift and had a few holes in it. The shop I went to just pounded out the dents and filled in the holes. That was 25 years ago, still going strong.

JB Weld or other 2 part epoxy would work great for that. I bring epoxy with on my canoe trips just in case. You can do a lot with epoxy and duct tape when things go wrong. My Grumman canoe was old and beat when I got it 25 years ago. It's still going strong due in part to epoxy.

Epoxy

You can use a product called ProSeal. It is widely used in the aviation industry to seal fuel tanks, seal windows in place, and seal thru holes where wire bundles go thru the pressure vessel.

It bonds extremely well to aluminum. It is resistant to UV rays. Would last forever on your canoe.

Old fashioned rivets are solid, easy and should last for ever. It's a two person job and should only take a few minutes. Lot's of you tube videos on it. Here is a good one that shows both closed rivets and standard rivets.
Aluminum Rivets