making side windows for boat

[badbowtie]

I have a boat top that snaps to my windshield and just covers my front to seats. It has zippers sewed on the sides to add clear vinyl to and then snap it to the side of the boat. I am not sure what gauge clear vinyl is used I am trying to figure this out. I also am not sure how to figure out what size zipper I have to order to sew to the clear vinyl to it to match the other half of the zipper that is sewed on the top already.