16ft Lund aluminium boat rivet size for bottom hull?

[Bknboat16]

Just drilled out some rivets from under a 16ft aluminium fishing boat tiller type , i have 3/16 inch rivets for it but when the rivets were removed the hole size on all of them are exactly 13/64 and the 3/16 rivets are loose fitting. Drilled out a couple that werent leaking and the same hole size is slightly larger. Is this done on purpose from factory so rivet will expand more or did lund use a slightly larger rivet for bottom of hull? ( used a small drill bit to start then a 3/16 drill bit to take a bit off the head of rivet , then knocked the head off with a chisel )

 

[Wildey]

Rivet holes are typically slightly oversize, especially in a production environment, to allow for slight misalignment and to ease/speed up the assembly process. (to a lesser degree in aircraft)
The bucking process, done properly, does swell the rivet substantially to fill the voids.

 

[airshot]

In the past when replacing rivets, I usually went with oversize rivets if the holes were sloppy. Years back they were easy to find. I made my own bucking tools and could make the rivets a tight fit. However, I still added some sealant to make them water tight. All jokes aside I have found " goop" to be a very good sealant and lasts a long time. Been on my aluminum jon boat for over 5 years with no issues.