: I tried 250#, all my weight plus a lot of bounce for good measure. The
: calculator suggested using solid titanium.

: Then I tried to reverse engineer a wood shaft. Allowing 6000psi for the wood,
: I figure you can put 50# in the middle. That seems light, but I really
: have no idea how much force rolling and aggressive bracing require. It
: sure seems like a lot of force at the time.

: Anyone with numbers, please step forward!

This discussion illustrates one of the major problems of designing paddles, kayaks, bicycles and similar items. It is easy enough to make a paddle, etc., pretty much as strong as you want to by engineering according to strength tables and other data. What is a hugh unknown and impossible to predict is what strength might be needed during an emergency, worse case situation. For instance, even if you knew the forces involved in aggressive bracing and built a paddle according, this paddle might be woefully inadequate when it was neccessary to use it to pry yourself and your kayak off a rock ledge in breaking surf. At some point the numbers seem almost irrelevent and this type of design become highly subjective and intuitive.