At the moment of edge change

[Horton]

Below are some potentially wacky ideas that have been rolling around in my head. I am not claiming any of this as fact.

 

At the moment of edge change if the skier is uncomfortable in some way they will tend to stay back, and lose connection early. As we all know if you lose connection early we will draw a narrower path to the ball. That “feels” fast but is really a disaster.

 

It makes sense that this would be related to how quickly the ski rolls over and or flows away from the handle. A narrower ski would tend to require more discipline from the skier to stay connected as a wider and more stable ski. Maybe.

 

Where this gets more interesting is if we talk about speed and load. For a given angle - the faster the ski (and skier) is at the center line the less pressure on the ski / load on the rope. Less pressure and load means the skier has more control and execute more precise movements. Less stress better control.

 

 

 

 

[bishop8950]

I believe this is definitely true: "Less pressure and load means the skier has more control and execute more precise movements. Less stress better control". And I think its true that " the faster the ski (and skier)" should be able to be lighter, therefore have more control.

 

My previous feeling was that if a ski was fast side to side, it was typically less forgiving in the turn. If I had a bad turn, I had no chance of moving into the center line in the desired way and started to fall behind on my faster ski. So I pick personally pick skis first by how they turn before I consider how quick they are. Other skiers will certainly look at this differently.

 

This is a shameless plug, but the Helix felt like the turns ripped and were plenty forgiving while having some nice side to side speed. I look forward to seeing if it displaces my rock solid turning but slower Quest.

[jimbrake]

@bishop8950 - and the Quest ain't all that slow.

[Bruce_Butterfield]

@Horton – potentially wacky ideas? Who would have guessed?

 

I disagree with the “less pressure, less load” idea. I think a strong load is critical, but the “evenness” of the load is often overlooked. You still have to have a strong load to generate the speed and angle required for short line, but the load must be as smooth as possible, or the loss of connection you mentioned will happen.

 

It helps to think of the rope like a spring – if you give it a hard yank right behind the boat, the boat will take it back with the same intensity and you have completely lost control. But if you “resist” as hard as you possibly can, and continue that resistance through the edge change and out to the buoy line, then the connection and control is maintained.

 

Easier said than done…….

 

[Razorskier1]

@Bruce_Butterfield I love that wording. Resist as hard as you can! Makes so much sense to me because it implies maintaining tension vs a load-unload type of style.

[rq0013]

That wording also sparked a light bulb for me as well

[Horton]

Ok @Butterfield

You went to engineering school and I went to NLU/ULM but whatever. Answer me this….

 

If angle at center line is a constant

Skier A is traveling at X mph at centerline

Skier B is traveling at X + 5 mph at centerline

Are you telling me that the load for skier B is not less?

 

[ToddL]

Maybe smooth load is what generates the + 5 mph

[Horton]

Sorry @ToddL‌ you are derailing the topic

[ToddL]

I respectfully disagree. I was truly suggesting that they are related.

[Horton]

Okay let me rephrase....

all other things being equal....

 

angle at center line is a constant

Skier A is traveling at X mph at centerline

Skier B is traveling at X + 5 mph at centerline

Are you telling me that the load for skier B is not less?

 

[Moggie]

While I don’t have the skiing ability to put this into practice, from a mathematical perspective I don’t get it.

 

There’s an equilibrium between angle, speed and load. If you increase the speed then you need to increase both angle and load. If you keep the angle constant then yes the load will reduce, but this is because you are no longer in equilibrium. What I mean by that is that you couldn’t maintain that speed at that angle and load indefinitely, eventually the speed would reduce to Skier A’s who is in equilibrium. Essentially you could only have generated that extra speed by taking greater angle and load earlier in the ski path; hence you can’t omit what’s necessary to generate the speed in the first place.

 

I could be way off with this, but that’s how I see it.

[Than_Bogan]

Why would the load be less? Its not a perfect analogy, but the basic principle should be like swinging a rock at the end of a string. The faster you swing it, the higher the line tension.

 

Is there something more complex at work here?

[Bruce_Butterfield]

Horton, you have it a little convoluted, so I'll rephrase.

 

If skier A and B have the same angle behind the boat, then B had to have more load to get his +5 mph, BUT he is now letting up (less load) and he will lose angle and be narrow to the buoy. That is the spring and release I mentioned.

 

A better way to think about this is if A and B are at the same point behind the boat and B is +5 mph, then B has to have more angle and more load on the rope.

 

In other words, your presumption of "all other things being equal" can't happen.

[Horton]

@‌ Bruce_Butterfield ok my mistake.

 

I was trying to not come out and say this but... since I change skis so much I definitely notice that on some skis it is much easier to stay connected and get extra wide. These are skis that take less effort and my my definition are much faster. I think that since they are faster I am less stressed at edge change and that gets me wider.

 

It is weird to change skis and feel like I am for sure holding on with two hands longer with some skis than others. There is some lesson here but I am a little fuzzy on what it is.

 

But.... now that i reread your above comment. If the ski is all the same....

If skier A and B have the same angle behind the boat, then B had to have more load to get his +5 mph,

I still disagree. What this means is something like.... a better exit from the previous ball. More water speed at the exit of the ball means less work to get to X mph. Why does more speed have to mean more work or load?

[Dusty]

Certainly can't ski as well as any of you but have watched a lot of great skiers from the boat and video, and once was a coach... In physics I know that Force = Mass x Acceleration. Mass is constant, and 'force' is line tension... Speed is acceleration x time. If you can create more tension (efficiently?) then speed should be greater for any given interval? (Downcourse speed is constant.)

I might suggest from observation that the ski seems to accelerate a little when the load is released, maybe because more of the ski surface is freed up and riding higher? Or maybe because they are releasing in aerated water?

[A_B]

@Dusty, it could be the kinetic energy of the line under load, and when released it creates the "whip" sensation.

 

I think @Horton's theory is plausible, because you can keep the ski on the back edge and still maintain outbound direction, without loading it with effort applied. The edge holding of a specific ski and fin setup plays a role in this and not all skis are equal or setup the same, so the degree of effort will vary.

[Than_Bogan]

@Dusty This is closer to a centripetal force situation in my opinion:

 

http://en.wikipedia.org/wiki/Centripetal_force

 

(Significantly edited. My first pass was starting from angular velosity, but this situation makes more more sense in terms of the tangential velosity.)

 

The starting point for approximating the line tension should be F = (mv^2)/r, where m is skier mass, r is the rope length, and v is the "tangential" velosity. When directly behind the boat, tangential velosity just means cross-coarse speed. So if you increase the velosity, all things being equal, the tension should increase in proportion to the square of the velosity. Also note that a shorter rope length leads to higher tension (if the other parameters are equal).

 

A full model would be more complicated, partly because of drag creating line tension even with no angular velocity, but mainly because you can catch up to the boat and slack the line. But that's impossible directly behind the boat, so the "simple" centripetal force formula should be pretty close at that point.

 

I strongly suspect that Horton has a valid coaching point in there, but I don't think the physics is being stated correctly yet. Bruce seems to be making sense with my understanding of the physics.

 

Nerd out.

[gator1]

John, you are not a fluid. Bernouli equation does not apply. Are you trying to say that on some ski designs you can get faster at the center and yet feel less load?

[Horton]

@Gator1 yes that seems obvious to me. (I am not saying I have a shred of science to back that up)

 

Every ski design has a different drag / acceleration profile.

[gator1]

So, in your "all other things being equal" post you are talking about skier A and skier B riding the same ski, at the center line, with the same acceleration, with the ski at the same angle to the center line,but at 5 mph different velocity? If so, then:

 

As other nerds have stated, centripetal load on the line must be greater.

 

wind drag, not inconsequential, increases with square of velocity, so to maintain 5 mph advantage rope load must be greater.

 

water drag, even less inconsequential, increases with square of velocity, so rope load is greater.

 

All heading in wrong direction to your hypothesis, based on what you feel.

 

My vote is that the key variable is acceleration. And your hypothetical situation does not match what you are feeling.

[The_MS]

How fast are skier A and Skier B at the moment of edge change? One would think that skier B would be to the point of edge change sooner but then what do you do to kill time until you ski around the ball. Do both skiers make it through the exit gates at 16.95 or does skier A take 17.04 to do it?

[Horton]

@mswhat do you do to kill time until you ski around the ball.

 

http://media.tumblr.com/fe497dd337d9af8479bb6398b9565d16/tumblr_inline_mg6n5ltl6X1rxe4lt.gif

[klindy]

@Horton that's easy - Like every other self-respecting Southern Canadian to kill time until @MS skis around the ball he either plays hockey, ice fish or drinks beer. Or at least he thinks about one or more of them!

[Horton]

@klindy‌ http://media.tumblr.com/fe497dd337d9af8479bb6398b9565d16/tumblr_inline_mg6n5ltl6X1rxe4lt.gif

[ForrestGump]

What is the angle of the dangle of each skier? I feel that may have an effect.

[Horton]

@ShaneH‌ http://media.tumblr.com/fe497dd337d9af8479bb6398b9565d16/tumblr_inline_mg6n5ltl6X1rxe4lt.gif

[Razorskier1]

What I do is stick my handle out as far as I can and get laid out down on the water while I'm wasting time waiting to turn around a ball. Isn't that how everybody does it?

[Horton]

http://media.tumblr.com/fe497dd337d9af8479bb6398b9565d16/tumblr_inline_mg6n5ltl6X1rxe4lt.gifhttp://media.tumblr.com/fe497dd337d9af8479bb6398b9565d16/tumblr_inline_mg6n5ltl6X1rxe4lt.gifhttp://media.tumblr.com/fe497dd337d9af8479bb6398b9565d16/tumblr_inline_mg6n5ltl6X1rxe4lt.gifhttp://media.tumblr.com/fe497dd337d9af8479bb6398b9565d16/tumblr_inline_mg6n5ltl6X1rxe4lt.gif

[mwetskier]

It seems to me hortin is correct -but theres a catch. his point is if the skier ' 'b' ' leaves the previous ball with more speed then ' 'a' ' he can be faster at the wake crossing then skier ' 'a' '. the catch is that its too obvious. its like saying if 1 car is going 5 mph and a 2nd car is going 10 mph and they both apply identical gas peddle 50 feet later the 2nd car will be going faster then the 1st car with out working harder. it will because it already had more speed to start with so the statement is technically true but doesnt explain how skier ' 'b' ' got his more speed off the ball to begin with.

[MattP]

My head hurts now. I think I'll just go to class and day dream about skiing.

[Texas6]

Congrats on the first 7 Panda thread to all included. I view this as a victory

[Horton]

This is why Moderated Threads was a good idea

[AdamCord]

Let me see if I can shed a little bit of light on this subject. @Horton's original question was something along the lines of "if a ski is fast, will that mean there is less load behind the boat and therefore does that make edge change and staying connected easier than with a slower ski?" - or something like that.

 

First off for anyone like me who hates a buried lead, the answer is YES.

 

Here's why:

It helps if we consider the extremes. Let's say ski A is a 59" kids ski that's soft as a noddle and sits really deep. It takes half the lake of submarining to get up on ski A. Ski B is a 69" ski with small bevels and shallow concave. It sits really high in the water and you can pop up without getting your hair wet.

 

On ski A: I pull out for my gates, turn in, and pull as hard as I can. What happens? Well the ski pushes deep in the water, it wants to go behind me, and creates a massive wall of spray. Do I go fast across the wakes? Of course not. But I'm pulling my brains out, so why can't I go faster? Remember that massive wall of spray? That's a LOT of water. Many gallons per second. Stop and think about how much energy it must take to move multiple gallons of water per second straight up in the air. It's a lot, and it's coming from the boat via your body. So all that load isn't generating speed. All that's happening is you're getting dragged down the lake sideways and you almost rupture a bicep.

 

Now on ski B: I pull out for my gates, turn in, and pull as hard as I can. What happens? The ski lifts up as it gains speed, it moves in front of me, and before I know it I'm going mach 1. Is there more load than ski A? Not even close. In this situation I've converted much less energy to spray and I've been dragged down the lake a much shorter distance. My energy has been converted into cross course speed. The load through my legs behind the boat is no more than my body weight because my speed dictates that I'm no longer just plowing down the lake making spray.

 

So it's not so much that a ski is faster and also has less load. A ski is faster BECAUSE there is less load.

 

Clear as mud?

[A_B]

@Horton, the first sentence of this thread seems to sum it up...

[Horton]

@Bruce_Butterfield‌ comments on what @AdamCord‌ said?

[The_MS]

I see only pandas and no answers. The point is that you cannot get ahead of the boat.

[Horton]

@ms say what?

[ToddL]

So, despite the off topic marking on my original post, it seems they are related as per @AdamCord's comments.

[Bruce_Butterfield]

@horton, Yes Adam is correct.

 

If you want to consider a more extreme example, put on a pair of 92"jumpers and compare the speed / load coming out of the buoy compared to a typical slalom ski and even you should be able to wrap your head around that. This example is also why I dislike "speed" as a descriptor of a slalom ski, but that's another long discussion.

 

That answer is not what you asked in your original question was, but seems like what you were looking for?

 

What I read in the original question is you have A and B are the same weight, on the same ski, come out of the buoy at the same speed, then if B then attains 5 mph more, he has to have both more load on the rope and more angle at the wakes. This is the goal. The hard part is not giving it all back on the edge change.

[The_MS]

@Horton The boat must stay in front of the skier. You cant fly over to the ball at mach speed, stand there and wait for the boat to pick you back up again. There is a perfect speed for each line length, to fast and you get slack, to slow and you cannot get the ski under you to create angle.

[Horton]

@Bruce_Butterfield

My mistake was thinking a vague question would yield better conversation.

 

 

 

 

[gator1]

@bruce_butterfield is right. And, engineers don't like vague questions. Or conversation. Social interaction's sole purpose is to transfer data and establish data superiority.

[klindy]

@bruce_butterfield has "The Knack".

 

http://www.youtube.com/watch?v=60P1xG32Feo&sns=em

[matthewbrown]

"all things being equal" doesn't work. something different had to occur for the extra 5mph. if, you lead out of the previous turn with your body ahead of the ski, more weight transferred toward the wakes rather than back, then you can create more speed with less load...this is of course at the acceleration phase. to guess the load behind the boat would be a bit hard due to all of the variables such as are you staying on your edge too long, did you pop up at the wakes...etc

[Razorskier1]

I am extremely proud to have been awarded 4 pandas! On a more serious note, this thread does provide some interesting food for thought. The question raised by @Horton is perhaps more unique to his situation since he never rides the same ski twice.

[thager]

I am really going to bear down and focus!!! That will be a very hard feet to scratch at!!!

[6balls]

Wasted energy is anything not going in the desired direction. Excess load is not directional energy for the desired path. It may produce a moment of additional speed, and perhaps a similar average speed, but with more highs and lows resulting in inefficiency. Doubt this just watch my sorry butt ski sometime and you will be convinced.

 

Watch the Olympic slalom skiers (snow) and tell me it's not all about speed maintenance particularly when one doesn't have the benefit of propulsive force. If you don't kill speed but carry speed from the ball, you don't have to be as fast at the wake but are still in front of the dude that killed it, honked on it for the speed, and now gets unloaded fast/narrow after the wash.