Fin tuning - how can it be so critical?

[Than_Bogan]

@AdamCord So ... many ... lever arms ...

 

This reminds me just a little bit of one of the easier-to-make demonstrations of extreme sensitivity to initial conditions (sometimes colloquially called chaotic dynamics): The double pendulum. Each has so much influence on the other that imperceptible differences in the state will result in very obviously different behavior a few moments later.

 

The interesting stuff starts about 20 seconds in:

 

[Horton]

looks like drone footage of @adamhcaldwell

[Fastguy888]

Pretty fun to try and scratch the surface of all the variables on a slalom run outside the skiers performance: Ski Shape, Ski Material, Ski Flex, Ski Weight, Fin, Fin Adjustment, Binding Type, Binding Adjustment, Boat, Boat Speed, Boat Path, Boat Weight / Balance, Water Temp, Water Chemistry / Salinity, Water Depth, Shore Shape, Water Surface Conditions, Wind Direction, Wind Resistance of Gear (or haircut if your @MarcusBrown).

 

All cumulatively important; what keeps the ski industry in business and fun to geek out on, but probably nothing more important than the skiers skill / performance.

 

 

 

[OTF]

Pluto- We will never forget you

[kurtis500]

I’m pretty confident that if someone added $100,000 to the prize money at every event you’d see more records go down than with micron level adjustments.

[Horton]

@kurtis500

[lpskier]

New record for quickest panda?

[ghutch]

@Horton your comment "To put it more simply - if I can not run my opening pass ( 32 off ) early and easy almost every time then something is wrong. That is the first place I will judge a ski and set up. It is not pass where the more minuscule issue arise but is a good starting place. When 32s are perfect I will work at 35 until it feels the way I want."

 

Doesn't this depend on short line set up? 28-32 will not feel as good but then the ski will start to come alive at 35 and 38? I remember Cord stating one time if your earlier passes feel off thats how you know its setup for shortline. I know there are alot of other factors here going on but if the ski is set up for the earlier passes, short line will be difficult.

[Horton]

@ghutch yes yes but if 32 is really super bad it is not going to get better

[h2onhk]

I think what @Than_Bogan is trying to tell us is that the adams need to develop a version of Denali with a dual hinge pivot point. If you don't cartwheel coming out of the turn, your ski form and fin settings must have been correct. Golf did it years ago. :D

 

 

 

 

[Fastguy888]

Curious where USAWS Rules Define what a Slalom Ski is? I would love to see some more radical designs. Would active changes to the ski be legal, like active aero in racecars. Wing tip angle changes based on ski speed using a small lipo battery and servo? Active flex / dampening? Additional small center skeg under bindings; helps my boat turn and track nice, lol. No science here, just day dreaming of some radical new designs. I assume these and other designs are rule regulated or tried and failed.

[MISkier]

Look at Rule 8.03

 

This section answers your question about active changes:

 

C. Slalom and Jump skis:

1. Any type of fixed fins may be used.

2. Devices affixed to the skis intended to control or adjust the skiing characteristics of the ski, for example, wings on a fin, are allowed as long as they are fixed and do not move or change during actual skiing.

[AdamCord]

@Horton sure if your opening pass is so bad that you might miss it then you have a problem with your ski. But if it's a little choppy, a little heavy, or you are running a little narrow that doesn't necessarily mean it won't be good when the rope gets shorter. If you spend all your time focusing on making a perfect opening pass you are doing a different sport than me.

[Horton]

@AdamCord yeah yeah

[kurtis500]

so whats the relation between the precise fin adjustment and the diameter if the hole(s) in the fin??

[JAS]

Do we really want to know? Does it really matter? The truth could be destabilize the waterskiing universe.

[Horton]

@kurtis500 none / irrelevant

[JackQ]

Many have different Philosophies, I have allways adjusted my ski for the shortest pass I can run. Don’t really care about my opener where i am less aggressive, way early and don’t have to scramble.

 

Can I tell .005 change, hell yes if length or depth. But for some reason I am tone deaf on forward/back, i can change .005 or.030 and cant tell a difference, I am sure i don’t have the optimal set up because of this.

[ghutch]

@AdamCord so...if those early passes feel like that I'm guessing at 35-38 the ski should feel alot better? Its hard to want to go on to shorter line lengths when it feels so off at longer line. This is something a skier just has to learn over time?

[Horton]

@ghutch let me try to clarify my view of what @AdamCord is talking about.

 

Using an ideal 38 setup at 32 may result in slower turns and or heavier loads than an ideal 32 setup. No one is saying that a setup where the ski substantially misbehaves is going to get better as the rope gets shorter.

 

[ghutch]

@Horton I understand that... just trying to figure out how much it can misbehave and then get better. This is some fun stuff to figure out. Thx for both viewpoints.

[swbca]

DIAGNOSE THIS PROBLEM

Watching the MasterCraft Pro tournament on YouTube, there was a woman skier, in the middle of a pack of 10, that was having a bad time on 2 and 4, her "on-side" at 35 off. Her D3 ski wouldn't turn, water was spraying up from her boots for a long time and she was breaking at the waist before the ski would turn . . . way to late.

 

The commentator made the comment that she needs to get her ski problems addressed.

If its possible, can anybody suggest what fin/wing adjustments she should make ? or should she just learn to get back on 2 and 4 like the best men on D3's

 

Its of interest to me, because that was the kind of problem I had to tune out of every stock ski I had, but that was before Fins were part of the tuning game. Occasionally I would get a ski setup to snap an on-side turn at excess speed with weight neutral - tip down.

 

[Bruce_Butterfield]

@swbca its next to impossible to correctly diagnose a ski issue with only that description. The cause and effect can be tricky to figure out and sometimes will be the opposite of what one would normally think. It could also be the majority of the problem is the skier.

 

If you can get a video snippet you will get a plethora of opinions on what to change.

[alex38]

Sorry if I didn’t read every post and this was discussed:

I believe in fin set up but run into too many variables (proper skiing technique mostly) to apply reliable assessments (to myself or anyone else).

However, I recently switched to a heavier gauge string on my guitar. After trying to ignore the extra tension, higher action, and onset of carpal tunnel syndrome I switched back and it was like butter.

The difference on the string with the largest variance was .006 of an inch!

Off topic me if needed, I was just happy to be talking thousandths of inches about something other than skiing. Rare.

[Horton]

So I don't think this thread ever actually addressed my original question. The thing that really perplexes me is how a DFT move of .003 is enough to make a difference. Obviously a move this small is only going to be noticeable to a very seasoned competitive shortline skier but nonetheless for that skier it could be the difference between a good setup and a great setup. It is unquestionably true that it makes a difference but it is still completely perplexing.

[skialex]

@Horton on a Goode? If you make a 0.003 dft move and keep fin length as it was.. yes I believe it is noticeable, if you move let say 0.003 forward and decrease Length by 0.003” then I don’t believe it would be that easy to notice. This is from personal observation, you probably know better.

[Horton]

@skialex I don't really expect to ever get a good answer but your comments align with my original question.

[Bruce_Butterfield]

@Horton the thing you are missing is that yes a good skier can tell the difference in a 0.003" movement, but the vast majority of that difference is in the skier's head. If you can't move your fin 0.020" in any direction and still run within a buoy or 2 of normal, your ski is either way out of whack to begin with or you are a total head case.

 

If you think that 0.003" makes the difference between a "good" and "great" setup, you are proving my point.

[jjackkrash]

It would be interesting to see some blind testing to see what the best skiers can actually notice. The results of blind testing is a real eye opener in the audio world.

[Horton]

@jjackkrash that would be super fun. It would take a lot of rides to do enough for it to be "scientific method".

[liquid d]

The answer is that it is very critical to get those last few bouys that you are capable of running. The problem is the that the numbers change according to all the other variables......

[matthewbrown]

As @jjackkrash said, the blind test is the true test. I couldn’t disagree more that .003 makes the difference between a good ski and a great ski. If my fin is 6.855 inches long, and I’m skiing well I should be able to move it to 6.865 and not notice anything at all or at least be able to intuitively compensate after the first couple off offside turns. But my performance should not change. That’s a .01 move which is considerably larger than the .003 used as an example. Too much energy spent on fin adjustments and not enough spent on technique. Now a change in boots on the other hand, that’s a different story.

[Horton]

@matthewbrown

 

Well with tools like https://www.mikro-just.com/ we now can have 1/32" binding moves also. I confess I rarely feel / or tweak bindings less than 1/10th inch.

 

Length and depth not as much but tiny DFT tweaks can be pretty eye opening.

[matthewbrown]

@Horton agreed, I think DFT is the most fidgety.

[RGilmore]

@Fastguy888

Some of what you're imagining is specifically disallowed By the AWSA equipment rules, to wit:

 

"C. Slalom and Jump skis:

1. Any type of fixed fins may be used.

2. Devices affixed to the skis intended to control or adjust the skiing characteristics of the ski, for example, wings on a fin, are allowed as long as they are fixed and do not move or change during actual skiing."

 

 

[Horton]

Some time in the 80s there was a system that moved your wing depending on your back heel pressure. Basically if you pushed your heel down the wing would be flat but if you lifted your heel at the ball the wing angle would increase. Cool but illegal. I wonder if that rule was written because of that system....

[AJL60]

Do we agree that binding movement fore and aft has the same effect as fin movement fore and aft (teeter totter)

[Horton]

@AJL60 Yes and no. From a simplified perspective yes. As you get into the weeds it becomes two different sets of adjustments.