does it have to be sandwiched?

[bajasurf]

I made a Mini Simmons with a 1/16th ply deck and its indestructible, also looks great.. I glued and vacuumed the ply to the 1 lb. foam with epoxy, then glassed 2-6oz bottom one 6oz top. 

I am thinking of doing it again on my next SUP, as I get depressions on the deck where my knees and feet are with 2-6oz glass. I guess I could go 3-6oz, but I am blown away at the deck on the simms, indestructible..The 1-lb I get is not high quality..

Okay, so should I glass under and over like your supposed to do it professionally or can I get away just over the ply with two 6oz?

Here is the reason I am asking, I can vacuum just fine, but never have vacuumed wet rails.  i can also do it like Greg Loher and just glass the bottom of the ply with 4oz, trim glue, vacuum,and then add two 6 oz layers on top. 

[Bean]

It sounds to me like you already know the answer bajasurf.  Sandwich (inner glass, ply, outerglass) will be stiffer and probably stronger overall than a single sided approach. 

I'm looking at an early Randy French, "wood" surftech long-board that suffered a buckle.  This board was made with a very heavy innerglass and fairly light outerglass. What is remarkable is that after many years of good use, this board has zero heel depressions.