I've been riding 47" long belly boards for a long time now. They are super fun and fast in small surf but I wanted something longer that I could get my hips and knees up on to, and that would maybe work a little better in bigger surf. The nose is 18.5", hips 16.5" and tail 19.5", length 5' 6". Thickness is 1/2" - 5/8", so its really flexy.
I'm finding it to be really fast across a steep face. Fore to aft balance is pretty critical for staying in control. Too far back the tail slides out and too far forward the nose does the same thing. But if you find the sweet spot it is quick and maneuverable.
Cedar with thin mahogany stringers