Potter 19 Window Reseal

[goobins]

New to me 2005 Potter 19 has small leaks coming out of 4 out of 6 windows. I want to replace the rivets with stainless screws and nuts. My boat is currently getting their bottom job done and I can't measure the diameter or length needed for the screws.
Does anyone know what size screws I would need to do this?

[Wila]

Late response, on my boat the port rivets are 1/8" aluminum pop rivets.

Assuming you're planning to drill them out, pull the port, clean/reseal and bolt them in?  If so I'd guess #8 pan head machine screws/flat washers and a lock nut. 

Hope that helps.