I will babble some while we wait for the more educated. Disregarding any gear or extra paddles that will be along on most trips, I would say the center of balance of the paddler. The trick is to find that center when your legs are properly extended and seated. I would guess it to be about in your groin area. You could sit on a board and place a fulcrum under it to find the balance, make sure the board is not a factor, keep it centered on the fulcrum. Let us know what you get!