How do you maximize "flex" in a wooden rib construction? The wooden surfboards I rode so far felt a bit stiff and dead compared to a modern epoxy board.
type of timber is a big factor. But I think it is similar principles to guitar construction: strong enough to support the force, thin enough to flex. You might need to reduce the thickness of your timber - you can also add a layer of fibreglass to the inside of your deck and bottom.