I went full nerd today and spent my lunch break at work modeling my plywood floor and support structure... I then ran a finite element analysis on it to determine the worst case deflection at different floor thicknesses. Yea I know... somethings wrong with me..
Oddly enough, it turns out that a polyester fiberglass lamination has almost exactly the same modulus of elasticity (stiffness) as plywood. So, at 1/2" thick, and 500 lbs dead center of the panel, there is a deflection of 0.162" and strain of 1.7% which is well within the limits of the plywood and fiberglass. So at 1/2", thats basically assuming only plywood, but I did a layer of CSM on the bottom and 2 on top with a layer of 10oz cloth.
A layer of 1.5oz CSM is roughly 0.04" thick, so that times 3 is 0.120" plus a layer of 10oz cloth is 0.0154" giving a total addition glass thickness of roughly 0.135". So that in addition to the plywood gives my current floor thickness as 0.635"
At that thickness, the same load and location gives a deflection of 0.082".
If I add two more layers of 1708, the deck will then be a total thickness of about .723" which gives a deflection of about 0.055".
All that being said... Two more layers of 1708 on top of the current deck will reduce the deflection fairly significantly and I'm no where near the strain required to cause cracking or failure of the laminate. AAAAAND thats with a 500lb point load... I'm not a miniature human, but I'm also no cow... I'm starting to think the extra glass will suffice... I'll probably put a little reinforcement in the ski locker because I'll have access, but other than that... I think I'm calling it a nerdy win lol
