8 layers of 5.6 oz "S" glass ends up being roughly 1/16" thick. Hmmm...I'd like it to be about twice as thick just for peace of mind but just 8 layers feels awfully tough.
I can bend this sample about 1/4" with my bare hands; certainly couldn't fold it without a vice and some pliers. But is it enough?
Addendum A user going by the handle 'monkey' frequents the Caferacer.net forums who does a lot of this stuff professionally. His current race tank build up process just uses 3 layers of 200g Carbon, and thinks this is more than enough, even 'gnarly': http://www.caferacer.net/forums/topic.asp?TOPIC_ID=9756