Kevin,

I think you would be buying yourself trouble. One of the wonderful things about plywood is its dimensional stability. A thick piece of solid wood might not be as dimensionally stable and could check or crack. I would also expect that a solid mahogany transom would be heavier than marine plywood of the same strength.

Perhaps you could apply mahogany veneer over the plywood transom.

Regards,

Dick

  Dick,

thank you very much. 

I think a solid mahogany transom would be magnificent!  Didn't somebody build a PocketShip with a solid transom for that very reason?  Anyway, with regards to movement, just orient the grain vertically so the "V" moves just a bit and the boat won't pull itself apart.  Would love to see pics!