Hanging weights on the shaft might straighten it, but for the shaft to permanently straighten it would really require the glue joint to slide. This would be hard to make happen and if you succeeded you would probably weaken the glue joint.

You could just make a bent-shaft paddle and say you did it on purpose.

: I've set out to build myself a paddle using Warren & Gidmark's book,
: "Canoe Paddles - a complete guide to making your own". I'm
: building a 3 piece paddle shaft which I glued last night. The shaft is
: 3/4" x 5/4" maple sandwiched between two 1/4" x 5/4"
: strips of ash. Now that the glue is dry, there is a slight curve in the
: shaft. Can this be straightened? I currently have it clamped down on one
: end with weight hanging on the other to counteract the bend in the boards.
: Is this a good idea? Will it work? How long will it take? Would steam
: (from an iron on wet cloths perhaps?) help the process or cause troubles
: of its own?

: Thanks in advance,
: Bryan