Continuing to try to wrap my own head around Jamie's lessons, and maybe help somebody (or hurt somebody!) as a result:
As far as relatively advanced skiers go, I've always been very clueless about this arm pressure thing. Yesterday my eyes were opened a bit. I don't "understand" yet, as I haven't even tried this on the water, but I learned something.
He showed me an on-land demonstration that was very interesting. When slightly past the (virtual) centerline, if you allow the leading arm to "give in" a bit and take most of the load on your trailing arm, it rotates your HIPS.
A LOT. (At least in my case.)
I did not know that. Try it and see what happens with your body.
So transfering the pressure to the trailing arm after the centerline has a cascading effect. First, it causes your hips to become more square to the rope. That rotates your ski's direction a little. And that should make it almost impossible to try to take the wrong angle (e.g. aiming too wide). AND it assures that the change of direction that Jamie was advocating after the centerline (see my other thread) is happening on a tight line, because it is being initiated BY the pull of the rope.
For those of us with a tendency to have our hips too closed after the centerline, this could be a great "trick" to get into the right body position.
Sure seems to make sense -- we'll see if I can make it work on the water!
Nathaniel Bogan -- GUT Padawan