An Introduction to GUT: A Scientific Approach to Slalom Skiing

[Razorskier1]

Part one is knowing what we need to do. Part two is figuring out the most efficient way to make that happen. That part, for me, required some time on the water with Adam and Adam in the boat. Hoping I can replicate it quickly again in the spring. It is critical to believe in what you are trying to achieve, and to stay on task, even if it seems difficult at first to conceptualize and implement.

[chris55]

Thank you to all of you who responded to me and I think I understand the concept since when I started slaloming last year (so I have only 2 seasons under my belt) I always tried to accelerate as much as possible from the buoy to the CL and try to edge change as soon as possible right after the CL and when I am able to do that then I feel I have enough speed to get to the next buoy without slack at the turn. I think and I hope I understand how I can apply this mental focus even at 15off and looking forward to shorter the line too. Thank you to all of you for sharing your knowledge.

And merry christmas !!!!!!

[Adam Caldwell]

@JackQ. Think of it like this. Short-line skiing can be related to golf, baseball, football, and many other sports where you are trying to transfer energy into an object with the objective to reach particular target.

 

Visualize an indoor golf course with a ceiling that is only 40 feet high. The first hole (15off) would be say ~ 10 yards out in front of you. You would probably pick up a sand-wedge to make sure the ball doesn't over shoot the target, and you wouldn't be too concerned about hitting the ceiling though you may come close. Now, lets look at the next hole (41off), where the hole might be say 100 yards out in front of you. Using sand-wedge no longer makes sense. Even hitting the ball as hard as you can will give it a trajectory that will slam into the ceiling long before it ever reaches the green 100 yards out.

 

The mentality of skiing "wide" is not all that different than using a sand wedge for the indoor golf 41-off green in the scenario above. It takes a lot more energy to hit the green at 100yards then at 20. If there isn’t enough understanding of the constraints of the system and giving the ball the proper trajectory, then you'll just keep driving the ball into the ceiling and fall short of the hole every time. For our 41off indoor hole, you need a different club, one that gives the ball a more optimal trajectory to land on the green without hitting the ceiling first.

 

Relating back to slalom, the handle path is a physical constraint of the system and is effectively the same indoor ceiling described above. A skier becoming “separated” from the handle is the same as the ball hitting the ceiling. The distance to the hole is equivalent to the height the skier needs to swing up on the boat to reach the ball.

 

It is relatively easy to swing up the short distance at 15off without much concern of hitting the ceiling. The arc of the handle path at 15off is very large (see figure in original GUT post) and the skiers path will not deviate from the fixed handle path much at all when focused on skiing “wide”. However, at short-line, the handle swings on a much tighter radius. Only being focused on skiing wide will cause the skier to separate too early (hit the ceiling) and cause them to fall short of the buoy before getting there. Better understanding of a trajectory that does not cause the skier not deviate from the handle path will allow them to stay connected much longer and not become separated (or hitting the ceiling) too early.

 

Proper trajectory that enables the skier to move with the system and its constraints, allows the apex to occur in a place that will naturally carry them through the back of the turn. The more we can understand how to work with the system rather than against it will make life easier, regardless of line-length.

 

[Than_Bogan]

Wow, I really like that ceiling analogy. At first I was wondering where you were going, but now I think that's a pretty powerful comparison, because you can really feel your energy dissipate if you do take your trajectory right into that "ceiling." Now I'm eager to see if this mental image can help me to not do that!

 

Btw, it's going to be 70 degrees in Massachusetts today. Why did we ever take out the course and our boats!!?

[6balls]

OK been visualizing this thinking very short lines and I get the concept thus far.

 

I'm assuming at longer lines like an opener I only want to be as high on the boat as necessary? For example at 28 off a guy can be very wide if he goes very high. Comments?

[ToddL]

This is all theoretical...

I'm sure we've all thought about our ski path through the course as like a sine wave of smooth, equal carving turns. We've also probably thought about the path in terms of straight lines directly from buoy to buoy. However...

 

So, the shortest path is a straight line from ball to ball, like a zig-zag path (saw-tooth wave) through the course. It is the most efficient in terms of distance to travel, but probably the most difficult. It is also the path which would likely have the most consistent skier speed through out, meaning the skier's max to min speed are very close to one another. Finally, the skier's speed would likely be closer to the boat's speed the whole time.

 

Thus, the longest path is like a square wave:

 

In order to ski the longest path, the skier must ski substantially faster overall to cover the significantly longer distance in the same amount of time that the boat moves the skier from buoy to buoy. Also, in this path, the skier is getting early width, so as to have more time to get high on the boat.

 

To me, the GUT approach is asking us to move away from a saw-tooth wave path and towards something more like square wave path.

 

I've always contemplated both a saw-tooth (gray) and a sine wave path when thinking about slalom. I've never thought about a square wave path (black). Clearly, a true square wave path cannot be achieved, but we can think about making our sine waves more square (blue):

 

@AdamCord , @adamhcaldwell - Is even remotely relevant?

 

[chris55]

Even for a beginer like me, the analogy and explanation are very clear, espacially following the path handle and even at 15off we need to stay connect to the handle.

@adamhcaldwell thank you for explaining so clearly and make it "simple" to understand.

[ToddL]

OK. Here's the graphic/animation that I want to see:

 

The skier's path through the course with three speed values along three different vectors:

Vector 1: Ski's path

Vector 2: Down course speed of the ski

Vector 3: Cross course spend of the ski

Visualize each vector as an arrow where the length of the arrow is representative of the speed.

Then, animate this through the course pathway.

 

For the cross course vector arrow, we can assume it will follow a pendulum like result, where as the ski moves from buoy 1 to center-line, the arrow is pointed to the left and is getting larger. From the center-line outbound the arrow is still pointing left, but is getting smaller. At the apex of the 2-ball turn, the cross course speed is zero and no arrow is visible; its length is zero. Immediately after the apex, the arrow is now pointing to the right and is getting larger as the ski approaches the center-line and so on.

 

For the down course vector arrow, it would be set in terms of deviation from boat speed. Thus, when a skier is straight behind the boat, the ski's down course speed is perfectly equal to the boat. The arrow is not visible, and its length is zero. However, when the skier is moving high up on the boat, the ski must be moving faster along the down course vector than the boat. The arrow would be getting longer pointed down course. At some point, the ski's down course vector speed will match the boat's speed out in during the turn; the vector value will be zero again, just like at the center line. Then, for some portion of the ski's path, the down course speed will be less than the boat's speed. (Think short-line skiers who wait for the boat to move out in front of them before loading the line.) Thus, when the ski's down course speed is less than the boat's speed, this vector will show an arrow pointing opposite the boat's path.

 

For the ski's actual path vector speed, this is what we feel. It is what I believe @Horton captured when testing out that wearable speed tracking device.

 

 

 

@AdamCord / @adamhcaldwell - Could you generate this animation if you had this data? Do you have this data?

 

With real data displayed via the above animation, I believe we can start to fully understand GUT.

 

I would hypothesize that the fluctuation of cross course vector speed and down course vector speed is the defining difference between short-line and long-line skiers. I would expect that short-line skiers have a different point at which the down course vector speed deviation reaches zero during the turn. I would think that adjusting technique to achieve that point is what defines success at each line length.

[Razorskier1]

Thing is, that isn't really the path. From ball to CL, that is the relevant path, although the ski is also slipping downcourse some. From CL to ball, the desired path is more direct. At CL, the direction of the ski changes. In the past I think many of us have mentally pictured it as (a) getting wide, (b) changing direction.

 

In GUT, you change direction to get wide!

[Wish]

No no no...stop all this GUT nonsense. Pull to the shore...lean harder....pull longer.. Ya...that's it. That's the ticket. ;-)

[chris55]

@Wish ......you wish......

[Razorskier1]

As I once said to my wife, "this sport would be so much easier if all I had to do is pull real hard!" Unfortunately, that isn't the key.

[Bruce_Butterfield]

@Toddl, wow. You overcomplicate things even more that Horton. I gave up trying to follow that about halfway through.

[AdamCord]

@ToddL If I understand you correctly I believe you have the right idea about where the velocity vectors would be pointed and how/when they would change. Also I'm not going say we should go out and ski a square wave, but the more we can achieve our stated goal, the higher our average speed will be and thus we will travel a longer path.

 

The important factor, though, is that the path of the skier is a function of the speed at which the handle rotates around the pylon. What that means is that there are constraints within the system, and we cannot just go out and ski whatever path we desire. If we can understand what those constraints are, then we can start to understand how we move the handle around the pylon fast, and get high on the boat quickly.

 

@6balls If you're to the level where you can get super high on the boat, and therefore super wide at 28off, then you can ski that pass however you want. I personally like to try and take the whole handle section outside of the buoy line. :D

 

We'll get way more into detail with this stuff in future segments. Luckily it's winter for most people on this forum :#

[Horton]

@AdamCord You mean I can not ski on a square path?

[AdamCord]

@Horton, I think you could if you tried hard enough, but the rest of us can't unfortunately.

[Horton]

@AdamCord now that I think about it, last time I watched @adamhcaldwell ski it did look like he was skiing a square path.

[AdamCord]

@Horton I TRY to take the entire handle section outside of the buoy line. @adamhcaldwell actually manages to do it. It's an odd sensation when you're driving and you can see him in your periphery at 32off.

[Zman]

Should future GUT posts be in Advanced Topics? Just saying....

[mwetskier]

what end would be served by limiting discussion and question to only those who already ski extreme short line? almost without a doubt the denali ski company cannot last long marketing only to the upper echelon of short line skiers so limiting the discussion and q&a regarding their slalom philosophy in *any* manner can only narrow their market.

[Zman]

Point taken. But, I do look foward to the Denali web site. The Adams are doing such a great job in laying this all out clearly, and building on it step by step.

[Wish]

Step by step is key.

[ToddL]

Step by step. Like a square wave. ;-)

[ToddL]

Thanks @AdamCord. The vectors are something that I think help compression of ski path and perception of speed.

 

Higher speed, longer path, higher on the boat sooner. Yep. That's what I was trying illustrate by a theoretical extreme square wave. Subtle realities sometimes elude us, but extremes can't be missed as proven by the comments above.

[KRoundy]

I though anything Denali was crazy or a joke / hoax and was just avoiding that whole Denali Log thing (I read through it once and was amused).

 

However: This is awesome and very helpful. Thanks!

[Adam Caldwell]

Squares are old news. There's something better. It's a geometric shape that goes to 11. The scientific term is "hendecagon". Ski the hendecagon.

 

[GaryWilkinson]

As I read the previous posts I was thinking as the simpleton that I am, that getting "wide" is the same as getting " high" (on my the boat), cynically saying same thing right.?!

 

Well that diagram really and clearly illustrates how they're related but different.

 

Well done, better skiing next summer getting high!