Watch for people throwing out 50'to early70's kitchen's ,all cabinet grade ply,no voids.My 2 cents worth on ply is this. I have found some really good ply on the back of old dressers and some areas of entertainment centers. Pieces seem very dry and brittle but once cut and shaped to what your building they came out very strong and no noted defects or air pockets also took to wetting and shaping by jig very well. I had some Mahogany ply for spars for the Taylor and it had nearly 15" of bad area were the outer ply started pealing from the rest and when cutting small gussets from same sheet I found numerous defects when cutting with razor knife. I think ply is much like a 1/2" x 4" piece of wood you must physically handle the wood for a bit and see what it will tell you.
I believe that oukome is lighter than the other woods and less rot resistant. Wood strength has a very strong relationship to density. BS marine ply should be void free and use glue more than suitable for us. I'd be quite happy to use varnished marine oukume.Taking this thread in another direction...I have worked a little with BS-certified marine grade okoume plywood and found it to be very good quality: strong, uniform, and light. Does anyone have a plywood strength and weight chart by species that includes okoume that could be used to calculate substitution of okoume plywood for mahogany, Douglas fir, or Finnish birch plywood?