: The hollow shaft is only stiffer because the material it's made from is
: stiffer. It is not possible for a hollow beam to be stiffer than a solid
: beam made with the same material and dimensions. You cannot stiffen a beam
: by removing material.

You may be correct - I'm an engineer by trade, but in the electrical specialty. My thought was that the center 1" core could be stiffened by the addition of the outer 3/8" layers - a composite construction, if you will. It works with plywood, does it not? Maybe it's just stiffer than my WRC paddle because of the sassafras and spanish cedar is stiffer, no?

The paddle was built by cutting out a 1" sassafras blank in the shape of the paddle outline. I then used a drill and a sabre saw to cut out a hole in the shaft and part of the paddle blades. The hollow is covered by laminations of 3/8" spanish cedar, and the outer shape of the paddle formed using standard spokeshave and plane techniques.

The final product is a standard shape GP, but the inside is hollowed out making the loom and handle lighter. The shaping of the blades reduces the weight of the ends, leaving the paddle lighter and better balanced than a solid paddle.

See the attached pic, or go back to the link above - I've added a crude drawing to help explain.