Chris Parker
Grandmaster
Physics wise, this isn't true, and archery-Japanese or western-comes down to physics. Yumi-the modern versions of the "classical Japanese bow," anyway-come in a variety of draw weights, starting at about 30 lbs. It's because of the Japanese draw that arrows are personalized-the draw actually ends behind the ear, and arrows have to be quite long for some people0it's for this reason that "draw weight" is a little more flexible for yumi-the draw is typically quantified as "between x and y lbs. at z inches.. In any case, higher draw weight means greater exit velocity, and kinetic energy, and this is what ultimately equates with "power," nothing more-you can't "generate greater power with lower actual draw power required"-that's physically impossible. This is, of course, all affected by draw length-the longer Japanese bow, and longer arrow and draw, means that there is a bigger drop off in velocity at higher draw weights-they're actually less efficient in generating speed and power than a recurve, but, because of all those things-the shape, length and draw length, they are actually conducive to more efficiency in releasing the arrow and hitting the target.
In kyudo,though, there are a variety of draw weights used, and the heavier draw weights launch the arrows faster, it's as simple as that.
In any case, the lightest of Japanese bows has around a 22-25 lbs. draw weight, which might not be legal for bear hunting-I think Alaska requires a peak draw weight of 50lbs. for brown bear, and, while I think it would actually be easier to draw a yumi with such a draw weight than a standard western recurve or longbow, it wouldn't be a simple matter-nor, I might add, would traipsing around in the field with a bow seven feet long and arrows that would be a little over three feet long -if you're anywhere near my size.....
Oh, I wasn't arguing against the basic physics there, just that the same draw weight for a Japanese bow and a compound bow (or even an old English longbow) don't really equal the same thing, due to the uneven dispersement of the draw. And as the rulings are geared around modern (Western) bows, taking them and transplanting them to Japanese bows doesn't really work in many cases.