ben2go said:
I would drill them to 1/4 inch to make sure the holes are good and use 1/4 inch rivets.Solid rivets are the best to use.Seal them with 3M 5200 marine sealant. https://www.grainger.com or https://www.aircraftspruce.com have the rivets and the sealant can be bought at some Lowe's and Walfart.
Agreed on the rivet part. Disagree on the sealant part. Solid rivets need no sealant. And, I would highly recommend against putting sealant under the rivet, before you buck it. When you buck it, the sealant will be forced out of there at a high rate of speed, and will make a mess of all surrounding it.