I've only used it for non-boating projects. It seemed a whole lot stiffer and heavier than the same thickness of okoume, so I'd be concerned if the boat had radical curves.

Laszlo

The plywood is the heart of your boat. It provides both shape and color. Don't skimp on it. If you can't get thin marine plywood locally, order it from CLC. Their quality is superb and it arrives in packaging that makes a perfect floor protector for your shop while you are building. I can get okuome from a supplier about 75 miles away, but bought from CLC. The savings in gas for the trip and state sales tax offset much of the shipping cost for me. -Wes

Baltic birch is too dense and heavy and brittle. 

I'm in NE MO, and made a trip to Plywood and Door in Chicago for a bunch of 4mm sheets of okoume- it's not "marine" or BS1088, but it seems at least 95% as good. There is a guy on the Fireball sailboat site that did a bunch of testing, and  came to a similar conclusion. I've also ordered BS1088 stuff at good prices from Noah's in Canada- probably not worthwhile unless you buy a bunch.