Did you know that the level of you feet inside a ski or wake board makes a big difference?
I am not talking of elevation, but rather the angle of you foot from back to front. In water skiing your heel should never be higher than the ball of your foot.
When your heel is higher than the ball of your foot, it can be compared to standing on high heels and trying to pull a few hundred pounds. Your whole body position is compromised and it is very difficult to pull the load. On the contrasting side, if you had your heels dug into the ground, you would have a stronger posture to pull a heavy load.
In water skiing, having your heel lower than the ball of your foot may not be the best (or safest) position (and I have not tried it before), but to have the ball and heel at least level will give you the strongest and most stable body position when making those sharp turns.