Posted by JimM on October 22, 2003 at 07:50:54:
In Reply to: light weight decking posted by al on October 21, 2003 at 11:34:54:
The strength of the deck is related to its thickness and support spacing. And the relationships may surprise you:
The bending moment due to a distributed load is proportional to the SQUARE of the spacing. Concentrated loads, like a size-12 boot, are worse.
But the biggest contributor: The stiffness of the deck is proportional to the CUBE of the THICKNESS!!
Using 1/4" plywood would require so much additional fiberglass that it would end up much heavier than a deck made of 3/4" ply. I would stick with materials recommended by the designer, unless you want to experiment with some high-tech materials like honeycomb core.
You could talk to the folks at www.nida-core.com for lighter weight alternatives to plywood. I'm considering it, but I think you'd have to use plywood or thick 'glass on top for impact resistance and to distribute the load into the core material. I wonder how much you'd really save in weight?