Disparity in fin depth measurements.

[Gloersen]

It seems like on some skis a discrepancy results when measuring fin depth on one side versus the other.

Occasionally a slight visual tilt can be seen as was the case with an ’09 Elite which turned out to be a flaw in the machining or casting of the mating surface on ½ of the fin block; easily cured with a file, after which the depth measured within .001 on either side.

 

 

Seen an HO A1 has a .004 disparity.

 

 

Now working on an ’11 Strada, the fin looks just fine visually when viewed from the back (maybe barely a tad tilt to the right). However depth measures 2.504 on the left (side typically measured) and 2.496 on the right. The bottom surface on either side seems perfectly symmetrical, its got to be a tilt of some sort. .008 difference just seem huge.

 

 

This gets in my head.

 

 

Anyone else ever noted these differences?

 

 

If so, what is the consensus for conventional wisdom as to which “depth†to assume is having the effect? Split the difference?......

 

[Dirt]

I have had the same problem on a couple different skis. I have 2011 Vice that has a pretty large difference. The Ball of Hair told me to measure it on the side with the allen heads on the fin block. I don't know the correct answer though.

[Horton]

I have wondered for a long time if anyone else knew about this.

 I guess you let the cat out of the bag.My assumption is most of us lay our ski down a bench with the tip of the ski to our left and the bottom of the ski facing us. If that is the case the fin block screws on every skiing industry should be facing up. If you measure the side of the fin facing up [the left side of the fin] your measurements are consistent.

I think this discovery may upset some people who always believed they knew what their measurement was. The truth is as long as your measurements are repeatable and consistent I'm not sure what the difference is.

I have enough skis around the house that I could do a survey and see the difference between all of them. I'm not going to bother because I'm pretty sure they all have a variance.

One of the things to take into account is that the fin slot on most modern skis is cut into the ski. This means that where the head of the caliber touches the ski is exactly adjacent to where the cutting tool went through the ski. My guess is if you had a special tool that moved over 1/2 inch, you would find the bottom surface of the ski is a more consistent distance from the deepest point of your fin depth.

The bottom line is, don't let this get in your head. Measure the way you measure and adjust the way you adjust.

[skibug]

If you always measure depth from the same face of the fin it shouldn't matter.  Unless if the tilt is inconsistent; meaning, it can tilt randomly to either side depending on the tightening of the clamp.  If it always tilts to the same side it shouldn't matter since you are always using the same reference points.

[eleeski]

Symmetry? Not on my skis!

If I don't like the way it measures, I add some Superfil to the low side.

Don't stress over measurements to .001. I don't stress over .01!

I wonder if a softer mount for the fin (rubber clamps) might be an advantage. Let the fin flop a bit. Flex matters?!

Eric

[RichardDoane]

dsmart - "Ball of Hair"... that's good....

[Deanoski]

the reseason is the calipers sit on a different part of the ski when the tip is to the left the flate end points twards the tip,   when the ski tip to the right the flat end of the caliper  has more surface twards the tail.

skis are thinner twards the tail thats why we all should measure with the tip to the left.  it water skiing not rocket science.

 

Deano

[eleeski]

It is rocket science! The space program is the source for the materials that go into my skis.

But .001 doesn't make a difference.

Eric

[Horton]

Eric,

I love you man but shut up. None of the Ballers ski on home made gear and do not understand that how really bad your advise is. I get that you are having fun but at some point you are missleading readers who are asking real questions.

[Dirt]

I enjoy reading Eric's posts. I think most know that Eric makes his own skis and cuts holes in his boats. Shut up is a bit harsh, try please be quiet if you want to silence him.

[Horton]

Eric can take it. You have to hit him with a big stick to get him to listen. I banned him for 2 minutes.... by accident now he gets the pink banner.

[eleeski]

Lisa loves my new banner!

Ballers should be the exact group who might be willing to experiment and actually reasonably evaluate modifications to a ski. They also understand at some level what goes into ski construction and setup. I will admit to being a tiny bit eccentric in my approach to skiing but my skis do perform adequately and some of my ideas are on track. Maybe better than conventional wisdom?

While I have always claimed .001 doesn't matter, it's interesting to see that changes that small are lost in ski manufacturing tolerances. I strenuously claim that you should not change your fin .001 but work on your form instead. If that kind of advice gets me banned, bummer.

Of course, adding .004 of superfil to make your ski symmetrical IS pretty bad advice. Realistically you should ban anybody who takes advice like that.

Still, I bet that hook that is common on many slalom ski tails started as a dollop of added superfil.

Just having fun!

Eric

[Old MS Accout]

Eric ROCKS

[Gloersen]

I’ll rip on an Eleeski anytime, as long as it’s symmetrical.

Deanoski:

Major oversight on my part; you’re spot on. The caliper’s max displacement measuring on the Left side is approx .25†further back on the fin and thus the head of the caliper on a thinner portion of the ski. At least .006†difference from top to bottom of bevel at sidewall from two measurements roughly ¼†apart at this part of the ski’s tail.

Good info.

Now I can ski rip with some other pesky concern.

1000x tougher than rocket science!

[JohnN]

I think you can measure it accurately being careful and using the depth indicator of the caliper.  I've had skis with a difference that went from couldn't dial it in to great by getting this consistent on both sides.  My Z7 measured pretty much perfect from the factory, however.  To level I just add strips of tape under one side of the fin block.  If you're really crazy you could add some hook to your turns by tilting the fin to benefit your style :-). 

John