FishyFish Tolman Alaskan Skiff and Boat Building Forums

If you can manage just the right amount of preload, you can bend the wood so that it slightly bows the other way and then glass the (now) hollow side.  I tried this once, screwing the wood down with a couple of slim pieces of wood (cut out the glass over the screws later).  It worked for the most part, but it was still bowed and not so evenly.  I decided it wasn't worth the effort.  Probably better to buy new flat MDO and seal it up with epoxy before it warps...

Brian

Exposure to heat on one side and moisture on the other might work.  I've done this on wide pine boards in the past.  Lay the warped wood on wet grass in the sun with the concave side downward.  The wood fibers on the concave side are shorter (drier) than the convex side.  They'll absorb moisture from the grass while the sun dries out the convex side.  Not sure how this would work with plywood, or even what the climate is in your location, but it might be worth a try.  Also I rarely see a piece of plywood that is perfectly straight when sighting down the 8' edge.  Maybe at least on the table you could incorporate some sort of stiffback to make it flat.

I worked in a plywood mill in the early 80s, when a specialty panel came out of the hot-press "canoe" shaped it was sold as shop grade. I spent 3 years laying up marine panels and my buddy worked downstairs in the scarf shop. (Oh if I'd only known I'd build someday.)

I worked in a plywood mill in the early 80s, when a specialty panel came out of the hot-press "canoe" shaped it was sold as shop grade. I spent 3 years laying up marine panels and my buddy worked downstairs in the scarf shop. (Oh if I'd only known I'd build someday.)

Vgager, I agree with the "should have" idea of stock piling reasonably priced plywood.

I worked in a major plywood factory for nearly 20 years. I was a panel patcher of marine plywood and got certified on running the scarfer. The boss let me make my own custom sheet one weekend for my new firewood trailer from 13-ply shop grade 3/4" marine plywood. It was 60" x 120". Shop grade was $0.03 per pound so got some for every boat project. I still have a few 48" x 168" 3/8 5-ply.

I've never had any luck trying to flatten out warped plywood.

I did see on a DIY slide-in camper build the guy made a light weight table from two panels of 1/4" plywood vacuum bagged with 2" pink foam as the core. The table edges were outlined in 3/4" pine lumber. He used contact glue like the old kitchen counter tops used. He put a block of plywood in the center core to attach the pedestal screws solidly. I've never tried it but hope to someday.

Dave