Ok, so I am trying to figure out what size doors I will need to provide adequate coverage on the ends of a tarp--both of which will be DIYed once I figure out the size of the tarp.

This will be for full coverage in diving rain, so I am guessing I will want the tarp to be 10 x 12 feet. Any recommendations on how to figure out the dimensions on the doors?

Or, for those of you who have door kits for your tarps, could someone let me know the dimensions?

Help appreciated!