Thank you Skunk, I was hoping to hear from you as you are truly a wealth of info..My peers called me the walking encyclopedia of construction back in the day, I would say you are that for this site!!
As for JJF's post, I based this number based on repair manuals that give you the ratio of thickness of glass to the amount of angled exposure each side of joint to lay up new glass. Not sure if I stated that correctly but anyway it's not a random number is the point.
Because I don't know what I am doing I actually researched a few things instead of winging as usual. you know with life on the line I figured perhaps I should