I have a screw in the bottom of my boat that replaced a lost rivet many years ago that is going to have to be replaced as it is leaking. It held up for a long time but I am considering going back with a blind closed end aluminum rivet sealed with 3m 5200 before the rivet is applied then covering rivet with some sort of 2 part epoxy or the like to seal the outside. The rivets I am finding around here are aluminum with steel mandrels which is why I am thinking I should epoxy outside as well. Any thoughts on repairing this way or would I be better of going back with a screw and sealer? Any other ideas are also certainly welcome.

Thanks

Pop rivets should be your absolute last choice!

If possible have it welded, my second choice would be a pan head screw & nut, then covered with JB weld.

I have any leaking rivets welded. Just a suggestion, before taking it to the shop put 3-4 inches of water in the hull and get underneath to check for other possible loose and leaking rivets. Mark them with a sharpie. That way you get them all taken care of at one time.

My boat has a floor and carpet and is full of foam floatation so getting to the backside to apply a nut or install a standard boat rivet is not an option at this time. I talked to a welding shop some time ago and they were concerned with igniting the foam.

Since welding seems to be out, and you cannot access the inside of the hull, here's what I'd try. You'll need the 3M 5200 and a larger screw.

Remove the screw and clean the area, including the hole. Put the 3M 5200 into the hole, and spread some on the area around the hole, the size of the screw head. 1/32" to 1/16" thick should suffice. Put a piece of wax paper over the 5200 and use anything with a flat surface to lightly press the 5200 flat. Do not compress the 5200 so it spreads to a thin film. Just enough to make a reasonably flat surface.

Leave the wax paper in place long enough to allow the 5200 to set up/cure. This could take as long as a week depending on temps and humidity. Once cured, put a good sized drop of 5200 on the cured material. This is to lock the screw in place.

insert the screw, and tighten it sufficiently to compress the cured 5200. When the 5200 you just used cures, you should be good to go. The screw should never loosen or back out.