Fin Measurement Tutorial

[bdougherty]

Can anyone point me to a tutorial that shows the correct way to measure your fin/wing and make appropriate adjustments? I have read the literature from the ski manufacture and reviewed the adjustment suggestions on various ski manufactures sites. I would like to see in picture or video form someone adjusting their fin so I can better understand where on the ski the measurements are taken. Also, any hints or tricks to make this as consistent as possible would be appreciated. Thanks, Bryan

[davemac]

Here is something.... d3skis.com/help_answer.asp?ID=17

 

There was a really good write up by Chris Rossi, but it seems as though his slalomguru website is not currently active.

[The_MS]

Good stuff Brent

[bdougherty]

Thanks for all the posts so far each one is very helpful! I have also concluded that this is not an exact science so numbers from someone else could be slightly different if the measurements are not done exactly the same.

[DW]

One key will be to mark or make sure you can replicate where you start from, so if you make a change you don't like or down the road you are way out, you can get back to your starting point. Pencil marks on the ski and fin are good markers.

 

The EZ fin tool, slot caliper are tools that make the job more repeatable. Each person will measure anything slightly differently, so keep that in mind. There are several good cause and effect charts/lists, Goode has one as an example.

 

Generalizing here, but Length is the longest length you can measure so right at the intersection of the fin to the ski bottom, Depth is the greatest measurment of the fin away from the ski bottom so at the peak of the lowest point of the fin and DFT, well that is a PIA, but the distance forward of the trailing edge of the fin to the tail (the tail is the difficult definition as it tends to be curved and hard to measure. That is the measurement you will struggle with and have more of a challenge comparing.

[SkiJay]

I discovered this handy little trick by accident, and it's such a cheap simple solution to

DFT measurment issues that it must be shared:

 

[davemac]

Interesting video....throws yet another variable as to the lack of consistency with the methods and reported DFT measurements. I've also wondered how much difference there is with the thickness of the jaws of different brands of calipers. When measuring the DFT, this would have significant effect over where the jaw contacts the bevelled rear edge of the ski.

[SkiJay]

This technique has absolutely NO effect on where the jaws hit the bevelled rear edge of the ski, or the fin, other than making it consistent. It doesn't add a variable; it removes a host of variables. You would get exactly the same measurement if you held the caliper perfectly in line with the base of the ski while measuring (the goal not quite achieved by slotted calipers as the slide dips into the concave while the stationary jaw pivots up on the ski's edges). The problem is that the tail of the ski has rocker, concave, and a rear edge that is both curved and not 90° to the base of the ski. All these curves make repeatable measurements nearly impossible. The ruler (or whatever you use to fill in the concave without lifting the caliper away from the ski's edges) provides a flat stable surface on which to lay the caliper taking most of the tail's curves out of the mix.

[davemac]

Gotcha...I get all that, and am all for it....that video solves a big part of the problem...getting a consistent and repeatable measurement. I just find the DFT measurement frustrating... and with the host of different tools, gizmos, and lack of standardization of measurement methods ...one person's numbers don't equal/translate to another person's numbers...that is the inconsistency variable I was trying to refer to. Heck, has it even been determined how consistent the rear bevel is from one ski to another (of same model)...as that would also factor in the measurement?

As a side note, I had a machinist friend cut a notch out of the "ruler" of my calipers. It surprised me how different the #'s register when using the slot vs not...with the same caliper....presumably due to the concave issue.

 

 

[ForrestGump]

Yes, you will find that there is an "offset" between the slot caliper and non slot. You have to take that into account. You can typically figure .020 difference you need to account for.

[MattP]

[Garn]

Great videos! Chris makes fin adjustment look easy.

[The_MS]

I am at .765 dft on my DFT 67. If he is using the slot to get that number I wonder if I am jacked up?

Chris or Eddie, what is the latest on DFT for a regular caliper?

[RichardDoane]

I'm @ .765 DFT on my 66"

[I5boi]

Good stuff. But I'd like to find a better explanation for the two (2) top setting screws and how to use them appropriately.

[TravisNW]

The set screws will make life way easier. Give the fin a pop to make sure it's seated up against the three set screws then use an Allen tool to adjust the fin via the screws. Real easy. Then when you move the fin start with quarter turns, measure frequently and the more you do that the more feel you will acquire and you will be dialed!

[Waternut]

As @davemac mentioned, lack of standardization makes this difficult. For those who are just getting into fin adjustment I think it's very important to understand how your ski manufacturer measures their fins. You'll save a lot of headaches once you learn this. Rossi shows how Radar does it in a youtube video shown above and D3 and Goode show how they do it on their website.

[6balls]

OK guilty confession...I have never measured my fin on any ski I have ever owned. I find the best binding spot first, then tinker a bit for what I'm after or think it needs...snug it up and call it good.

Pretty low tech, I know. Skied with Andy last fall, he didn't adjust it at all...thought it looked good for me both sides of the wake.

[Steven_Haines]

this question seems to fit in with the context here. yesterday I was skiing and got the feeling of my ski slowing down to fast or getting behind me on my off side turn. other than that the ski feels pretty good. one thought would be to go back a little bit with my bindings. but looking at some of the recommendations posted above, it looks like adding a little more depth might be the answer to. any ideas?

thanks Steve

[I5boi]

I wasn't able to locate this anywhere but it appears that the front set screw is for length, the middle is for depth and the rear is for DFT and combinations for diagonal. I'm not making any changes yet, just wanted to get to the factory setup which I was told it would be when I purchased it but it was not so.

 

Thanks for all your input. Much appreciated!!

[Drago]

@steven haines, take a little length out. But first, see it it happens tomorrow. Yesterday was only one day

[Steven_Haines]

@Drago,

I'll try that. thank you for the suggestion! I may have been getting tired also as I haven't been skiing much.

thanks again!

Steve

[lpskier]

Hey, I just noticed that my ski (red Fogmans and camo sock) are featured in the screen shot for the second video. Aren't I the big shot...

[TallSkinnyGuy]

I used this thread today and the video above to help me learn how to adjust my fin. I am just trying to set my fin to factory settings (was delivered with fin quite far from factory settings). I thought I was doing well when I got the DFT and depth just right, but I can't get enough length because the adjusting screw hits the top of the ski and stops before I can get the front of the fin down enough to get the length I need. I then loosed everything up and tried shifting the fin around to re-position it and started again. Got DFT and depth perfect but then again not enough length. What am I doing wrong?

[MISkier]

@TallSkinnyGuy, I believe I have had to remove the front adjusting screw on my skis in order to allow the fin to protrude through the top of the fin box to get the correct length. Others may have more insight. I would probably just take that screw out permanently.

[lpskier]

Your fin is hitting an obstruction. The solution is to file away the fin at the obstruction point to create the space needed to make the adjustment. If you have an HO, I noticed last spring that you couldn't get the recommended numbers on a 68 VTX without a file. I believe this issue was later resolved. I had to do the same thing with my T3 to get the numbers I wanted.

 

If you do modify your fin, make sure to remove any burr on the fin. If the fin has a burr it may not seat correctly in the clamp and then might move when in use.

[TallSkinnyGuy]

Actually, my problem is the opposite of what you guys are describing -- it seems I don't have enough fin material under the front adjusting screw (rather than too much that has to be filed away). It seems my fin is not hitting an obstruction but rather the adjusting screw is hitting an obstruction (the obstruction is the top of the ski) making the adjusting screw not be able to push the front of the fin down enough to get the necessary length. Should I just forget about using the adjusting screw and simply use my fingers to pull/push the fin into position? Would there be any downside to that?

[BraceMaker]

Just helps the adjustment but it can also help keep it from shifting - you might also do well with a dog point set screw - so long as the dog is narrow enough on the screw dimension to go into the slot.

 

https://www.mcmaster.com/#dog-point-set-screws/=19s3vu9

[S1Pitts]

@TallSkinnyGuy I am hearing you. I bought a ski that the previous owner ran a very short length fin on by filing off the top of the fin and slot where the front set screw contacted. I had to replace the fin in order to achieve stock fin placement. Pull that fin out and have a look. It's very obvious if it's been filed because the anodizing will be gone off the edge of the fin.

@6balls I am with you on moving the fin until I get it feeling more to my liking, then I start to measure when the final tweaking starts to get that last little bit dialed in. I quite often go to extremes just to see how sensitive the ski is to each parameter to get a feel for what kind of resolution to use: IE 1/4 set screw turns or 1/2 turns.

 

[TallSkinnyGuy]

I'm working on a brand new 2017 Radar Senate Graphite, so no previous owner to make modifications. Seems odd to me that I can't achieve "factory" settings on a new ski using the supplied adjusting screws. I figured I must be missing something and not smart enough to figure it out (still concerned that might be the case).

[TallSkinnyGuy]

So I just spent some more time trying to adjust the fin and found that if I cranked down hard enough on the front adjusting screw it would crush down the surface of the ski enough to reach the fin and move it. Kind of a bummer to have to crush the ski surface, but it is obviously all covered up under the fin block, so not an aesthetic issue.

 

I was then able to get all the settings correct and am now looking forward to trying the ski with factory settings. I skied it twice last week before measuring the fin and was surprised how far off the fin was from factory specs when I measured it for the first time yesterday.

[S1Pitts]

I would be talking to someone at Radar - Should not have to be crushing the surface below the fin block in order to achieve published stock fin settings on the Radar site.

[TallSkinnyGuy]

I ultimately did talk to Brooks and he told me they had fixed that problem in Senates going forward, so I suspect that means it isn't an issue for the 2018 line.

[C5Quest]

Had the same issues on my 17 Senate Lithium. The fin block doesn't really allow for factory settings. I took the whole block apart and filed the fin which gave better numbers. The 18 models now use the a new fin block which comes on the Vapor models. I'll be swapping out to the new block next time I'm down at Perf Ski.