Skiing is a way of moving that is characterized by dealing and controlling two physical forces; gravity and rotation energy. Rotation energy is created at the moment a turn is started. This energy can only be successfully absorbed by the body when the body does not have a so-called absolute pivot point. This is also the reason why the upper leg is always moved slightly forward during the second half of a turn when alpine skiing. If both feet would remain exactly next to each other when alpine skiing, it would be very difficult to end a turn.
When boardskiing, both feet are positioned similar to when alpine skiing and turns can be made rapidly after each other without using counter forces from the upper part of the body. When transferring the weight from one foot to the other, both feet are automatically in the right position. When the body weight is distributed equally over both feet, both feet are positioned straight next to each other.