Originally Posted by justanotherskipro
From there how do movements like braquage not change foot to foot distance yet change the ski to ski distance? How does lateral angulation at hip change the distance between the legs without changing the distance between the pivot points.
All in all the stance question comes down to a relationship to the surface we are standing on. The base of support being a two dimentional construct where we measure area between contact points on that surface. How the body articulates and how wide the legs end up becomes less important than how stability is effected by base of support width.
Since you will not answer my questions I will attempt to answer yours.
I would argue that the base of support is not a two dimensional thing' as you say, since the distance between our bases of support are often changing in three dimensions.
To address your question, stand upon feet flat upon a slippery surface. Exert leg rotation and the feet will rotate as they do with bracquage. You will clearly see that, as you say, the distance between the feet does not change although the distance between your skis (if you have skis on) will decrease. I could provide illustrations but I think it should be evident this is occurring. No mystery there.
Now stand with your skis "locked" in because they are on edge and exert the same leg rotation forces. Your feet will not turn because edge engagement will not allow that. The force instead will act upon the pelvis (the "free-er component in the system). The force will act upon the pelvis to turn the pelvis. This is countering. Now your skis will resist rotation but they are free to slide in the direction they are pointed so a second effect of this will be to cause the distance between the feet to increase in the direction the skis are pointed. This is what Ron LeMaster refers to as an increase in fore and aft stance distance. You could of course resist this but, as you say, the distance between the hip sockets being a fixed one this is what naturally occurs.
Now, you might think this would result in the skis becoming closer together as they do in the above cited example of bracquage. Inclination however generally accompanies countering, This requires the lateral distance between the feet to increase (what Ron LeMaster refers to as an increase in lateral stance distance and what you evidentally refer to as an increase in vertical distance). This has to happen when inclination increases because otherwise you would trip over your inside foot while inclining your legs to the inside of the turn or your outside ski would necessarily have to come off the ground.
I think this increase in lateral stance distance or distance between the bases of support is evident in the following photo. The skier shown displays inclination, countering and angulation.
its more pronounced in this image:(perhaps because inclination is greater)
Incidentally (but a little off topic)This explanation is I think a good illustration of the significance of leg rotation in advanced skiing. People often question why we encourage the use of leg rotation to guide the skis in a gliding wedge. The effect of this rotation of turning the skis tends to go away as the skier experiences increased edge angles but hopefully the learning persists and leg rotation persists in some fashion as a feature of the student's skiing as he or she progresses toward advanced skiing. Countering becomes a feature of the student's skiing as edge angles increase and is retained throughout his development.
This is a feature often lacking in a person's skiing and students are often exhorted to include counter as if it were an isolated movement instead of a feature of skills progression. Skill development (of all the skills) ought to be a feature of good skiing at any level