Wade,

It sure is "great stuff".  I'd like to hear more about though.  It would seem that the one handed gate has a lot to do with how early he "displaces water to the outside."  A two handed gate would have you flat and unable to begin  moving until later.  One handed, you are moving out to apex and more able to move in earlier.  Am I getting this???

Deke

Thomas Wayne wrote:

most importantly, understanding how Rossi's gate works MUST be applied to this photo.  Given his incredible efficiency in initiating his COM movement outward and the fact that he has a very smooth one-handed gate transition, I would argue that he's only actually begun his movement back toward the gate at right about where the #1/B line intersects his ski's path.  When the ski is on it's "turning" edge  - but still moving OUTWARD - it leaves a distinctive curl to the boat-side edge of the ski track that is unmistakable - note the "white water" appearance right up to the #1/B line.  Therefore, not coincidentally, the track left in the water clearly indicates that his ski is continuing to move outward right up to that point.
TW

Absolutely Correct!

Wade, I'm trying to understand this comment.

I am trying to begin my motion toward the gates when #1 is in the middle at every line length.  (Hint; you need your hips forward and your elbows touching your vest or you will miss the gates)

What do you mean when you say #1 is in the middle?

And hips forward elbows touching vest, where should this occur?

I've been trying to figure out my gates this year. I'm having trouble with my -38 start (or my issues really surface here) I try to get up on the boat and make an easy turn in for the gates, but find myself with little or no tension on the rope to the point of almost having slack. I've noticed that at the point of reach/turn in, I've been reaching forward and allowing my backside to fall behind and not getting a good counter (like you would in the turn) I've been working on this (countering an pushing my R hip forward) and it helps but still think I have a timing issue. My approach has been, pull out at the 55's with the same intensity, reach/counter when I feel tension on the rope and then try to turn back in towards the wakes with little or no intensity. It seems that the less I try (intensity wise) I have better results. I know, I need a lesson BIG TIME!!!

Thanks Man!

Last edited by Steven Haines (Thu, Oct 1, 2009 1:48 PM)

My major point on this is that when you take the overhead view, this looks pretty different. Here is a to-scale diagram.
(buoys enlarged from scale for reading purposes)

I disagree with the illustration Wade posted above on the "theoretical best line" through the gate, as the skier's speed would be off the charts.  As angle increases, speed increases, it's a mathematical equation (distance travelled x time = speed).  There comes a point of diminishing return on both sides; too much speed is no good nor is too little.  What Chris Rossi is doing is skiing a line that gives him the correct amount of speed for what he is trying to accomplish.  He could easily get more angle or less but he has chosen a path that produces the results he is comfortable with!  He does this all the way down the course.  Being that maintainable cross course angle and speed are directly related, load must also be.  Being that load is the enemy, we must do everything within our power to ski as smoothly as possible with the most efficient angle, not the most.

Thomas Wayne wrote:

Unless I'm looking at a different photo than you are, point "C" falls BETWEEN  point "A" and point "B", which is not how you've illustrated it...

Correct again! Schnitz's lines are not level with the water's surface. Mine are.

I don't agree with the theoretical "best" line at all.  I would call it the theoretical "latest" line.  This is going where the square wave discussion went a few years ago.  It is the "impossible line" where speed and load would have to equal infinity.

Steven, A and B are not ski lines they are site lines.  Just visual cues.

This is a GREAT topic!

Last edited by Deke (Thu, Oct 1, 2009 5:26 PM)

You might argue that the theoretical best line would be straight from one buoy to the next.  This would be minimum load, minimum distance travelled, and minimum speed.  In theory, all of those parameters would be CONSTANT.  The only acelleration would be angular.  OTOH in the square wave scenario all of those parameters would be INFINITE.  We have a better chance of developing technology and technique to be CONSTANT than we do of being INFINITE!

Below is an illustration created from a CAD drawing of the course.  It's to exact scale, except for the buoy diameters (per Wade's example).  The active elements shown are:

1) Wade's "theoretical best-gate [optimum] line" (broken purple line)

2) Sight lines drawn through the 1-ball and each gate buoy (broken light blue lines), with their corresponding points (“A” & “B”) on the 2-4-6 line

3) "C" is placed where I interpret it's position from Schnitz's photo and from his description: "C is where Rossi started displacing water to the outside or prior to #1 being in the middle of the gates" (never presuming to know what Steve is thinking, I could be wrong about this interpretation)

4) A skier's theoretical path incorporating a wake crossing of 35 degrees and a turn-in radius of 15 feet (solid dark blue line)

Notes:

     a) the "theoretical best-gate line" presumes the ski brushing both gate balls, achieving maximum possible angle; in reality this is impossible, but if it was possible the angle would even greater than shown because [in the real world] the gate balls separate by several extra inches due to the boat wake.

     b) the sight lines through the 1-ball can only be approximate, since the skier's viewpoint is very dependent on his body position - that is to say, head tipped back or tilted sideways a few inches will greatly change how he views this buoy alignment.

     c) a wake-crossing angle of 35 degrees was determined by analyzing still shots captured from overhead video of skilled -35' skiers; obviously different skiing style will vary this angle to some degree (pun intended).

     d) a turn radius of 15 feet was suggested in articles written by Steve Schnitz during his "skiing by coordinates" days; again, different skiers will undoubtedly produce different radii.



Of course, the reality of skiing cannot be expressed as easily as such CAD drawings would suggest.  In the real world every turn (including turning in for the gates) has an ever-changing radius that cannot be expressed in terms of a simple arc, and there are no long straight lines in the skier's path (excluding a glide following pullout).

I believe that the typical skier path is much better described as one continuous right turn blending seamlessly into a continuous left turn blending into a continuous right turn... and so on.  For this reason, the angle of crossing can only be an approximation (at best) derived from the ski path during the brief time it is passing directly behind the boat - this is the closest we can come to estimating that angle, since it’s the only time the path is even close to being a straight line (again, excluding a pre-course prolonged glide).

TW

Last edited by Thomas Wayne (Wed, Oct 7, 2009 3:34 AM)

Again, I disagree with Wade but agree at the same time.  You see, I want to ski the perfect line, which is both the fastest, and slowest line combined.  Any deviation from the perfect line is inefficient.  Therefore, any speed faster or slower than the perfect line is detrimental to performance!  If 90 degrees were obtainable from one side of the course to the other, the skier would need to be going faster than the speed of light.  This would be the fastest line.  This would not be beneficial nor would skiing at the next buoy.  Somewhere in between lies the perfect line.  Think of the slalom course as a target.  For the easy speeds and line lengths, you just need to hit the target somewhere.  As the speeds and line lengths become harder, the skier needs more accuracy until finally, a bulls eye is necessary every time!

Chuck Norris could ski the square wave. Believe it.

JAS wrote:
Nice discussion but not sure what you can actually take from photo (taken with telephoto lens from grassy knoll).  One example of discrepancy is distance on line "A" from gate to ball one, compared to distance on like"B" from gate to ball one. Certainly not the same as Wade's to scale diagram. Warren commission will  have plenty to talk about.

Assume "A" to be the point where the line running through the centers of the 1-ball and the right-hand gate ball intersects the 2-4-6 line, and assume "B" to be the point where the line running through the centers of the 1-ball and the left-hand gate ball intersects the 2-4-6 line.  Further assume a course set to exact nominal dimensions.

The distance between A and B in the real world is almost exactly 39 feet.

TW

Last edited by Thomas Wayne (Wed, Oct 7, 2009 3:36 AM)