The theory of the asymetrical blade is it will put less torque on your wrist as you put it in the water. To accomplish this you paddle with the longer side on top. In this way the top and bottom half of the blades should enter the water more simultaneously than if they were symetrical.

Since you should really fully submerge the blade before applying power, the asymetrical blade should be unnecessary. And the amount of torque would be pretty small anyway. But, it looks cool and sounds "techy" so people continue to use asymetrical paddles.

: I'm building a paddle with an asymmetrical shape (per Nick's book). I can't
: figure out which is the top of the blade and which is the bottom! Is the
: lower half of the blade slightly longer and narrower than the top, or vice
: versa?

: while I have your attention... WHY is the asymmetric shape good? My distant
: and foggy mechanical engineering intuition suggests that a turning moment
: around the shaft axis would be the result. Although top & bottom are
: the same area, the reaction of the blade to the water resistance is
: further from the shaft axis on one side than the other. What's the scoop?

: Thanks in advance

: Les