What's the difference between night and day? 0.004 inches.

[MISkier]

The water temp fin adjustment PSA thread from @AdamCord is very timely. In addition to watching some accomplished skiers struggle very recently with our warmer than usual water this season, I just exited a very enlightening period of fin misadventure.

 

In response to a couple of tough sets late in the season last year, I wanted to get my ski to roll up on edge a little bit more and change edges more quickly to liven it up. So, I took out .004 of depth. I didn't ski much more before shutting down for the season, so I didn't spend a lot of time after that change. I don't think I skied much differently and certainly not better in that colder Fall water. So, that experience was quickly dismissed and forgotten.

 

At the beginning of this season, we had super high water levels and tons of kickback rollers from shore. It was also very windy. I struggled a lot, blamed the rollers and conditions, and somehow landed on the idea of moving my binding back a bit (I don't remember why). At some point, I arrived at the unavoidable conclusion that my skiing sucked. I seriously began to think it was over and time to step back, at least partially.

 

A month or so later, I didn't like how the ski was turning, so I moved the binding forward to it's original location to see if I could introduce some smear on my offside. I succeeded, but I still was skiing really narrow with the most awkward gates in 10 years. After another month (and lots of 90 degree heat), the tail was sliding excessively on the offside. So, I figured I would just add back the .004 of depth I took out in the first place. It was so bad for me at that point that I broke my cardinal rule and made that change the night before a tournament and didn't even ski a practice with it.

 

All throughout this, I was missing a lot of passes I should make, including openers. And, the completed passes seemed difficult and were scrambles. I don't think I had a gate and one ball I liked during the entire odyssey. I began to dread the next set or next tournament.

 

Unbelievable difference after the change (well, actually, undoing the original change). Everything was better. The pullout, glide, gate, turns, space and width all improved. It all made sense. Without the depth, I had likely been sliding downcourse on everything. Suddenly, I was early and retaining angle. Gone was the awkwardness of the gates and the ski was efficiently building speed again. I got a score that was acceptable (not my best), but I skied some passes easily and fairly well without all that work and disappointment from before. I even enjoyed it somewhat.

 

So, I have returned the exact same settings I had on everything and have started to ski at a previous level with much better potential to get fully back on track and improve.

 

Lesson learned. The hard way. And, it only took one change of 0.004" to initally enter that abyss.

[GregHind]

@MISkier that makes me wonder. If that’s what you get for adding .004”, what would you get if you added .008”!!!

[MISkier]

@GregHind, at this point, I’m going to ride out the season. If I’m so inclined, I could try something else at the end of this season and the beginning of the next.

 

But, that’s a good question. What would a little more depth do?

[jordanh]

I'm just a free skier and only have the skills to be a set it and forget it type of person. Also never skied a course so feel free to tell me to see myself out... But given these tolerances listed it truly makes me question certain things.

 

What's being used to measure these adjustments? If you are truly saying .004" is going to make or break your set then I would assume you are using a depth micrometer, or some sort of precision height gauge vs a typical 6" caliper. Please tell you are not using your caliper as a height gauge to set a fin at .004" . Standard practice in manufacturing is to require a finer measuring tool than a caliper on tolerances finer than +/-.005".

 

How often are these setups being checked. Are tournament skiers checking their setups before every set? What if their ski falls over on the dock, etc?

 

Only other sport that I can think of that would require such tolerances in equipment setup would be precision shooting.

 

More or less trying to educate myself as I didn't realize slalom had gotten to this lever of fin setup that two hairs is what it takes(I have thin hair, thank my mom).

 

 

[MISkier]

@jordanh, I believe I am measuring my fin the same way most everyone else does - with a caliper. But, it’s 8”. A 6” won’t work for fin length.

 

I check the measurements occasionally - probably twice a season. It doesn’t move. Of course, I don’t stand on my ski when it is resting on the fin. That part hangs over the dock or the platform.

[Bruce_Butterfield]

By far the biggest difference 0.004” makes is between the ears ?

[MISkier]

@Bruce_Butterfield, that’s what I originally thought, too, until I could actually notice the substantial difference. I also thought the same thing about a 0.030” nylon washer for an offset fin depth. That also was very noticeable.

[jordanh]

I think a blind test is in order. Have a competent individual set your ski up that you trust. He gets to pick one of the two settings. Ski your set. Write down where the fin setting is. Then verify the setting to see if you could truly tell.

 

How long until skiers are tightening their BOAs with torque wrenches and lacing up with tension gauges ?

[MISkier]

Someone else can do that test. I just got my sanity back.

[Cnewbert]

0.004” is the diameter of a typical human hair.

[VONMAN]

Yes, and it will make a difference because that little change makes more fin area in the water.

[oneski]

I’ve frequently said that with fin and bindings settings if you’re off by a little, you’re off by a lot.

[Kimbymon]

@VONMAN I ran 28.6mph again today and got 2@ 30.4mph. Thanks for adjusting my fin yesterday

[VONMAN]

@Kimbymon That's great! Keep slaying those buoys.

 

[DaveD]

@MISkier After snapping that ski in half the other week, are you thinking that 0.004" adjustment was the key to success?

[MISkier]

@DaveD, I think that recent change back to the original setting just compensated slightly for the likely overall decline in performance from a suspected structural compromise. It bought me some improvement and did change the ski in a positive way, but it’s possible the overall timing of my issues was coincidental, not necessarily cause and effect. The ski could have started failing late last year when I made the first change and worsened until I reverted the change and saw some improvement. It is true that I still wasn’t skiing up to my previous level after fixing that setting, but far better than I had been.

 

Great crash after it broke, though. That made skiing the State tournament the next day a bit tougher from a physical and equipment perspective.