How Much Added Runner Plank Stiffness with Glass Fiber?

[wnethercote]

I have never wrapped a runner plank with glass fiber, but have generally just epoxied and varnished the bare wood.

I have added 6 inch wide strips of 12 uni to the bottom of a plank: one 4 ft strip took a 94 lbs/in plank to 100 lbs/in.  Adding another 5 ft and then a 6 ft strip took it from 100 lbs/in to 113 lbs/in.  So it looks like you get  +6 lbs/in per 6 inch wide strip of uni on the bottom, applied wet under squeeged-out peel ply.

Has anyone done before and after stiffness measurements with a full wrap of (say) 6 ounce glass cloth?  I am tempted to try a wrap, but don't want to ruin a good basic plank by making it too stiff.  At my present weight I need a pretty soft runner plank (85 lbs/in or so).