A Winter's Tale on Stats

lhoover

If it is cold in Houston (lake temp was 59* yesterday, darned cold for us), then it must be really cold everywhere else, thus spurring more talk and less play. The [email protected] club (we know everything: just ask us!) at our lake was discussing the Rope Tension or strain gauge stat being used at pro tournaments to show the force being exerted on the pylon. This is pretty cool, demonstrating to the world how strong we all are and that this ain't no sissy sport, this high end slalom. Unfortunately, this stat has pretty much zero relevance to a podium finish.

Think of other sports that are saturated with stats, both individual and team, that are directly related to being a winner. For instance, the ERA in baseball, the QB rating in football, or GIR in golf. If they are dominating that stat, they are more than likely dominating that sport. Not so with the strain gauge. It's groovy, but irrelevant to top performance.

Then what is for slalom? Is there a particular stat that is most telling? Perhaps a Lean gauge, that is, max angle away from the boat? Max speed at the apex of the turn? Max speed at the prop wash? What say ye?

Happy Winter skiing to all, and may Spring be just around the corner!

MISkier

I would think a relevant stat would be the distance and time expended from the apex of the turn (or minimum speed) to max speed. That is, how quick and in what amount of distance can you accelerate? The distance could be measured either in how far the boat travels downcourse or how much the skier travels in a combined arc and pseudo-straight line across the course.

The point would be to see how much earlier the skier is into their edge change and how much space before the buoy the skier is because of this effort.

Another stat would be minimum speed at the buoy. How much speed can the skier retain all the way through the apex of the turn and into the hookup/pull?

ALPJr

Consistent buoy count? Must be getting closer to winter.

skier2788

Average speed. I think the Min. And Max. Speed could vary a lot and probly significantly more the shorter line you go. The best in the world are great at maintaining speed. So to me I think the average speed of the skier would show a lot.

BobF

I've thought about both of the speed issues (max behind the boat and max vs min). One of my consistent keys this past season is to think about achieving the most speed into the wakes efficiently and as quickly as possible.

The average speed, though - shouldn't that be nearly identical for each skier at the same boat speed? Don't all skiers cover roughly the same distance in the same 16.95 seconds gate to gate @ 34?

ReallyGottaSki

I concur peak force is not indicative of success, force over time exerted (impulse) getting closer to relevance when normalized to skier mass but Newton-sec or Pound-sec is still not as sexy as as a unit like horsepower

lpskier

I think the stat that is clearly most indicative of success is “number of podiums.”

BraceMaker

What about rotational angle of rope on pylon one would presume that at nearly any rope length the angle the rope comes up the boat would be directly related to all the speed and acceleration metrics plus you can extrapolate distance travelled.

DaveD

To @skier2788 point, I think it would be interesting to see if there's a correlation between buoy count and the max vs min speed of the skier through the pass. Maybe standard deviation of the ski's speed from gate to gate would tell the story?

Is there a small water proof gps unit that can be mounted to a ski (or binding) that will transmit speed readings?

lazzn

How about something more broad, a stat connecting like the skier's average tournament placement podium wise to their average tournament score in buoys. Or maybe other things too like their consistency in runoffs. Or even adding in a connection to how the skiers score compares to others in the tournament, so its a factor of the competition level, how they actually skied numbers wise, and whether they had pressure put on them to ski well

Oldkier

I was playing with my garmin watch under bike mode, I don't know how accurate but this was 34mph 32 off

Oldkier

8 passes

H2OkieNC

I think I'm with @BobF and @DaveD. When I tried to model handle path, it seemed to me that the most EFFICIENT skier at a given boat speed/line length would have the lowest max speed and the highest min speed (this may relate to being "light on the line"?). This wouldn't necessarily go with the best buoy count, but if you are comparing two skiers with same size, strength, weight, I would think the one with lowest max speed and highest min speed theoretically has POTENTIAL to run more buoys. Something like this should be a more useful metric than rope tension, as high rope tension seems like inefficiency to me.

H2OkieNC

@oldkier that is interesting, 49 mph max seems the right ballpark. If you could see more higher resolution data of only the time in the course, would be even more interesting.

Tom351

Here is some telemetry over video of a pass at 32/15off... The gauge in the top left is cross-course angle (I set it up to show difference between skier path and course heading- so it is a negative value when pulling 1-2/3-4/5-6)

Oldkier

@H20kieNC I started garmin on ski platform and stopped when finished set. Next time I will start garmen right before pull out and stop after exit gate on each pass.

MISkier

@Tom351, that is some cool stuff. What is the device taking the measurements and the software combining the video and graphs?

ALPJr

Stats are are great. I’m often accused of analysis paralysis, but at the end of the game what really matters?

https://www.connellyskis.com/uploads/1/0/3/7/103766634/joelhowleyworldchamp_orig.jpg


https://www.connellyskis.com/uploads/1/0/3/7/103766634/manonworldchampion_orig.jpg

Tom351

@MISkier the GPS data is from a GoPro- I believe it was Hero6 in that video, but I have done the same with my newer Hero7. I have a Hero9 but have not been able to do anything with the GPS data yet. The video overlay was done using a program called Dashware.. more info on that in the thread linked below. Also, if you have any questions about GoPro/Dashware feel free to message me as I can probably save you some trial/error if you start to do your own:

https://www.ballofspray.com/forum#/discussion/20292/slalom-telemetry-gopro-hero6-black