I'm looking at slalom ski's, have slalomed quite a bit many years ago, used to watch slalom skiing on TV and am getting back into skiing this year. Back in the day I remember the skiiers on TV making "4 buoys at 36 feet" and that made perfect sense. My question is, now that I'm getting back into skiing, I see the term "I ski (X)-feet off" (insert whatever number). What does this mean?