Do longer skis turn slower than shorter skis? Where's the data?

[thager]

This has always been accepted as fact but where's the proof?

[Spineofgoo]

SUV vs tractor trailer. Which one turns faster?

[Horton]

wheel base...

[Spineofgoo]

Apples vs oranges?

[thager]

I doubt very much that a person uses the full length of a ski to turn so I think the wheelbase argument is B.S. Some of my best skis were longer than accepted for my weight and turned better than the same model shorter ski. Rocker, shovel, surface area, flex, bevel etc. have a bigger effect on on turn radius. Not talking common accepted sense here. Where's the proof?

[JackQ]

Different skis have different characteristics, but for the same ski, yes longer will turn slower but be more stable and accelerate more. Try a 64” and then 68 or 70” of the same model, what need any data after that. I subscribe to the adage “ski on the largest ski you can turn” I typically end up with a ski that is longer than the mfg recommends for my weight.

[Spineofgoo]

@thager,why then are the Adams going 65 across the board?

[thager]

@JackQ I agree, but I know so many skiers that will not even try a longer ski and that is always the response. It turns quicker. I have always been on a 66" etc.

[thager]

@Spineofgoo Money. Efficiency. Cost.

[skialex]

I ride longer than suggested by the manufacturer. I’m in the camp “ride the longer ski you can turn”

[Than_Bogan]

I think we have to be surprisingly careful in defining "easy to turn." In slalom, we hope to accomplish several things in the turn. One is to rotate the ski (what the Denali folks call Yaw and I like to call around-Z). I claim the basic physics requires that a shorter ski is better at that task.

 

But another task is to carve a relatively tight radius, and yet a third task is to change the direction of our velocity so that we can head the other way. For these critical tasks, it's a lot more ambiguous what role length plays. Or, more specifically, within a "reasonable" range of lengths, other characteristics might dominate the effects of length.

 

So I also believe that skier style makes a big difference. I personally have never had any success with skis on the long end. I just don't understand how to take advantage of the things a longer ski can do better.

[Spineofgoo]

Shorter skis seem to stall in the turns on me. I'm 6' 190.longer skis seem to generate more speed.

[skialex]

Cross course speed and carrying speed through the turn are good things for me. Stop and go skis require more physical strength which doesn’t suit my style (I think).

 

[DanE]

So how is ski lenght most accurately defined? Total lenght or front boot location? Front boot location to rear end of fin?

[Horton]

Ok @thager I guess you want real answers. Well I do not think there is necessarily an easy or short answer. Here is a first pass....

 

To start with, The idea of a longer ski is a misnomer. Longer skis are generally proportionally wider. In the case of D3, Connelly and Radar I believe that the skis are exactly proportional. If a 67 is one inch longer than a 66 it is also roughly .010 wider at your front toes (depending on the ski shape). That width means that if everything else is the same the wider ski will make more speed and slow down more slowly. All of this certainly impacts turn radius.

 

Ok so take width out of the equation: A slalom turn is a controlled slide. The tail of the ski slides wide the path of the skier. Call if smear or oversteer or yaw or whatever. The point is that the skier is exerting pressure to slide the tail of the ski and/or the front of the ski is pulling to the inside which also puts pressure on the tail to slide outward. The greater the distance there is between the skiers feet and the fin the less leverage is put on the tail to slide. This can be demonstrated by moving bindings - a ski that is too loose at apex will slide less with bindings slightly forward.

 

The trick is to find the right size ski for your skiing. Undersized skis suck as bad as oversize skis. Some skiers are going to not match up with the factory recommendations because we do not all ski exactly the same.

 

[thager]

@Horton Agreed. It's a long winter! With all the tuning nuances available now I am thinking bigger sizes are not such a big problem anymore. Big ski won't slow down? Put an s-wing on it, etc.

[Dirt]

It depends more on the total surface area than the length.

[Stevie Boy]

These are just my thoughts, right or wrong, at 5ft 6ins short, I have done my best skiing on a 66 inch ski, because of my weight, I now ski on a 67inch and I have recently started to ski really well on it.

But technology has made it possible for longer skis to turn much better than in the past, I have a ski buddy that skis on a 64 that should be skiing on a 66/67, his total take on the whole thing is that regardless of ski and ski setup if you continue to ski on it, your body/mind will adapt and you will ski on

I do think that unless you are in the very advanced level, changing your ski and setup on a regular basis is not going to help you, more time on the water with what you have will.

 

How well you turn a ski could be Height/Length related going back years ago, ski selection was generally based on your height, but obviously skis have changed a great deal since then.

[Jordan]

Curious about the effect of flex. I would think if we were to compare two skis that were exactly the same except for flex that the softer ski would turn better. In other words, if the ski bent into an arc during the turn, it would seem to help the turn.

Or would it?

If the turn was just a carving action then the answer would be yes, but we know that the tail needs to slide more or less depending on the skier.

For example, when I watch Nate turn his onside, he seems to make the tail slide rather abruptly arriving at hook up very quickly. We know that he uses a 67 inch ski and likes a long/shallow setup. It seems that he achieves that Z type turn overcoming any disadvantage from the longer ski, then immediately receiving the advantage of a longer ski at hook up to moving across the wake.

I have always thought that the women ski on proportionately longer skis for their weight. I have no data but they are often on 66 inch skis at 120, 130 pounds or so...

I wonder just how much the pro skiers who have factory support, experiment with different layups of the same ski before they settle on their choice?

 

Gotta love winter!

[DW]

@thager - to the way you wrote the question, are you questioning the actual turn velocity or what we are all 'guessing' the turn radius?

If the latter, I would think the more key parameter would be distance from fin Cp to Binding Cp and that parameter having an effect on turn radius (along with a lot of other factors as noted in the thread). Or maybe even more key, distance from fin Cp to forward water breaking point (lets see how we will all measure that one:-)

[JAS]

No proof, Denali, it’s in the Science it seems.

[Horton]

@dw that is what I said

[eleeski]

At the risk of getting banned again, the turn is NOT a controlled slide! A good turn will minimize any sliding - and certainly not feel like it is sliding. Trick skis which slide easily aren't the best slalom skis and keeping them from slipping is critical for slippery slalom. Most slalom skiers would be best served by following a solid carving edge. The best skiers don't slide the ski as much as punch it deeper in the water.

 

A deep shortline turn is not perfectly carved or linear. A shorter ski can move easier - especially in a forced turn. But the turn isn't everything. The long ski will carve better, hold edges and angle better and be more stable - all very desirable traits especially crossing the wakes.

 

Length is just one factor in the feel of a ski. Rocker, tunnel, edges, width, shape, weight and flex matter as much as length. Try your ski to see if it fits you. And part of the trial is being willing to move binding and fin - sometimes a lot (especially if the ski isn't conventionally sized for you). You might be surprised by what can work for you.

 

Eric

[thager]

Do we really need a crazy fast turn? Probably talking milliseconds here. How well a skier uses extension and then quick compression from their core to hip initiating the turn has a big effect on how fast the ski turns. Trying to turn a ski on a loose rope will be slower and inconsistent as well. In the old days when you couldn't tune or move binding adjust wings, etc. it made sense to me. Smaller was better, but now?

 

[Than_Bogan]

@eleeski I kind of disagree with you because I do think sliding is important, but overall I like your comments and I decided it was more "Like" than "Disagree."

[Stevie Boy]

When the ski slides are you losing time, surely you must lose momentum, a race car driver does not always take the shortest route, same with snow skiing the more you can keep the skis in contact with the snow the quicker you are ?

[thager]

@Stevie Boy Warren Witherall wrote a great article on that. Wonder if I can find it. Used to be included in the AWSA membership packet way way way back!

[Horton]

@Stevie Boy a slalom ski is in a constant state of slide.

[Horton]

@eleeski I can't give you more Pandas but no

[Spineofgoo]

@Stevie Boy watch a sprint car race,con state of slide. Faster than a raped ape!

[Spineofgoo]

Constant

[eleeski]

A downcourse component of motion does not guarantee slippage (and most skiers would appreciate a ski that minimizes slipping away distance downcourse). At the apex of the turn, the ski is aligned with the boat so there is zero slippage during part of the turn. Any ski slippage characteristics of a ski will be least important in the turn.

 

Sometimes I earn my pandas. Sometimes the "common knowledge" deserves the panda.

 

Eric

[Horton]

@eleeski I know you are working on your HOF nomination but seriously no.

[Spineofgoo]

@eleeski,if a ski didn't have some degree of slippage it would pitch you out the front or you would high side,G forces would come into play. @Horton?

[eleeski]

@Horton I don't understand you. "No"? To what?

 

Ski slippage has NEVER been a good thing for buoy count. Until some recent voodoo engineering explanations come along. (Remember coordinates?) I'm not going to Guyana with Jim Jones to drink Koolaid either. Panda me again if just having a dissenting opinion based on decades of experience that disagrees with the trend du jour is wrong.

 

Get on roller blades (which don't slip much). Have a friend pull you behind a bike. Weave around like running a course. You can run a sinuous path (like a slalom course) with no slipping.

 

@Spineofgoo An F1 car will easily outrun a drifting car by sticking to its line. Sprint cars are fast because of minimal rule limits - but not as fast as other race classes (that don't skid away their speed). And in the real world, there is slippage. It's just something that is minimized for optimal performance.

 

Eric

BSME (Bachelors of Science in Mechanical Engineering - not social media management)

[Spineofgoo]

@eleeski,the first 2 letters are correct BS you are comparing a solid environment to a liquid one.apples vs oranges.and a sprint car will turn faster lap times than f1.2 different surfaces,again apples vs oranges.

[Horton]

@eleeski if the following is true...

 

Any ski slippage characteristics of a ski will be least important in the turn

 

Why not use much deeper and longer fins? Why not have a deeper concave at the tail of the ski? Why not run the fin as far back as possible?

[Horton]

@eleeski also what is the cause of spray?

[Zman]

And, it's only December.....

[bishop8950]

@horton thanks for all your effort and moderation.

 

 

[Horton]

@eleeski comment?

[slow]

Every carve has some degree of slipping it wont hold the carve. Even on ice skates you to sink into the ice ever so slightly.

[eleeski]

@Horton Does the fin actually do that much relative to slippage in the turn? Big old Vogue fins were able to run passes. Fins are effective at controlling the angle a ski achieves. At the narrow tail, it is most effective. I did mount a fin mid ski - it didn't feel good. Fin placement relative to the back of the ski matters a lot. Not sure how that affects slippage or how big a ski feels. I wonder if a 60 inch ski with a fin hanging 4 inches out the back would work? Geometrically, the fin is a minor factor in ski slippage when a ski is on an acute edge - like in a turn.

 

A concave bottom tends to make a ski ride deeper. Why would you want the tail to ride deeper? Instead, lift on the tail when at a steep angle will make a tighter radius turn and keep the tip down - both good characteristics. That's probably why most skis have a relatively flat tail.

 

Spray is generated by the speed of the ski, the pressure on the ski and the angle of the ski to the water and direction of travel.

 

The underwater picture shows minimal slippage by the buoy and a non carved turn after the buoy. Is that because the ski is slipping or the tail has been stuffed deeper in the turn because the front of the ski is not slipping? It's certainly not a sideslide.

 

Note that if the ski was slipping (along the lines of what a flat trick ski will do) the ski would be quite a bit further downcourse. Would you be able to get the ski heading cross course? You'd be late for the next buoy. Real world slippage may happen - but too much limits your buoy count.

 

For some reason, you have embraced slippage as a critical factor in ski design.

I'd agree if minimizing it is the critical factor. But slipping downcourse is NOT a good feature of a ski. A ski that is loose in the turn is not going to feel good - unless the alternative is too locked in. Ski design is a balance between stability and responsiveness that is personal. Every person will have different preferences. Someone whose preferences are different from yours is not wrong.

 

@Spineofgoo I did Google Sprint cars before posting. They run on both dirt and pavement. F1 runs on pavement so there is overlap. Google also noted a significant advantage to F1 in speeds the cars attain. Your statement about solid vs liquid???

 

I'll stand by my claims - and my engineering understanding.

 

And I usually like shorter skis because I can set them up to turn tighter and hold more angle across the wake - no theoretical basis just a lot of empirical experience. I do run my bindings quite forward as well but that's a different thread.

 

Eric

[TEL]

You guys are giving me a headache, I am glad I just go out and ski and not over think whats going on or I would never enjoy this sport.

[Stevie Boy]

@TEL This is Sport, it automatically takes over, when people are staring at perfect water that is too cold, unless you want to put all the clobber on.

It is a waiting game that drives water skiers stir crazy.

 

I apologise for being off topic

 

[Than_Bogan]

@TEL That may be true for you, but there are some who find trying to figure out the physics to be one of the entertaining pieces of the sport!

 

If I'm reading between the lines correctly, the "opinion gap" here is smaller than it sounds. It's more about emphasis and focus than a fundamental disagreement about physics.

 

Suppose I ask "Is the Empire State Building big?" There is no correct answer, but only a follow-up question: "Compared to what?"

[UWSkier]

Water is awesome. There's never any slippage. That's why my Response LX goes 41 MPH at 3600 RPM with a 12p prop. :)

 

(3600x60)/5280

[ALPJr]

I think for me a little extra length helps in two ways - I’m 6’2” and feel more stable with slight for and aft movements on a 68 vs. a 67. Also feel likes it’s a little easier to work for angle and speed across course. Never had any trouble turning sharp, to sharp sometimes, but seldom not sharp enough. I tried a couple of the wider 67’s and didn’t get a good for and aft feel.

[VONMAN]

Nate weights probably 150-155 and skies on a 67 inch ski. Kind of out of the normal weight to length charts. But the added length/volume (yes Horton I said it) allows him to keep the ski moving.

I've found you can make a long ski, ski/feel like a short ski. But you can't make a short ski feel like a long ski if your body weight is over powering the ski. you can't keep it moving without sinking at the ball loosing speed and then work to regain your speed back.

That was the old days. Now we have Science! Now I'm on a 65" ski, skiing at 32mph and loving it. all because its a wider ski with more volume. It doesn't loose speed and auto turns in the blink of a eye. And yes all skis slide.

[Horton]

Not really about ski length but...

 

@eleeski

To really clarify this we need to use the right words. Below are my definitions specifically for this argument.

 

1] YAW is a movement around the center of the ski that changes the direction it is pointing, to the left or right of its direction of motion. In a race car, oversteer and yaw are basically the same thing. Tail slide is a yaw movement. Smear is a term I have abandoned because the readers of this forum have too many definitions for what it means. To me, smear means a yaw approaching and leaving the ball.

 

2] A SLIDE is any movement of the WHOLE ski in a direction not in the same direction as the ski is pointing. 4 wheel drift is a slide. (I am aware this is not a typical definition of "slide")

 

Throughout the course the ski is almost always in a state of slide and a state of yaw. If the skier pulls past centerline, then exactly at centerline, the ski is sliding in the same direction as boat and at the same speed as the boat. Think about that for a second. If you are leaning on the rope at centerline then at that exact moment, in addition to your cross course speed, you and the ski are moving down the lake in the same direction and speed as the boat. I am sliding down course at 55k every time I cross the wakes.

 

As the skier transitions from pulling edge to turning edge and heads out to the next ball the tail of the ski is on a path that is outside of the path of the skiers feet. The ski is in a state of yaw / oversteer / smear. The longitudinal axis of the ski is pointing inside the path of the skiers feet. The best skiers in the world yaw the ski farther and earlier than the rest of us.

 

At the same time the ski is also in a state of slide as the skier’s feet and the whole ski slide away from the path of the handle.

 

One definition of an ideal turn might seem more carving then yawing but for the ski to rotate enough to make cross course angle the tip of the ski must point inside the direction of travel and the tail of the ski must travel outside the path of the skiers feet. That is yaw / oversteer / smear.

 

Leaving the ball yaw is less of a factor as is slide. A more efficient skier might carry more speed to the inside and prevent some of the slide but as long as the rope is tight the boat is dragging the skier down the lake.

 

So - the ski is almost always in a state of slide and yaw. The amount of slide or yaw can be seen by the amount of spray. Spray is literally the result of water displaced by the ski. A ski going straight and not siding or yawing makes a minimum amount of spray. Maximum spray is created by the ski that is in the greatest state of yaw & slide with the most force. That is not to say that a bigger spray is a sign of better skiing or ski setup.