missing rivets

Hey guys, im new to the site i just picked up another boat it a 1988 16' smoker craft, its missing a few rivets on the bottom of the haul. The previous owner had patched it with a nut and bolt and rubber washer and siliconed them in. I am wondering if theres a way to fix this, or if i should just leave it as is, i've tried to find rivets big enough for the holes around me but the biggest i could find at the marinas around me are 3/16. Any suggestions would be much appreciated.

If it doesn't leak, I'd leave it unless you have another reason to replace them.

Aircraft Spruce will probably have the rivet you are looking for.