Fin grooves

[dskunhardt]

Hi everyone,

 

I wanted to try milling some grooves over my fin, still don't know if horizontally or diagonal or even s pattern.

 

Just wondering if any of you have already tried this? Or if not but have some good ideas on mind I'm willing to try them.

 

Let's see where can we go with this.

[RGilmore]

It's been done. Somebody on here a few years ago posted a fin he had milled vertical step-grooves into, with the anticipated benefit being... I have no idea.

[aupatking]

Go for it! If you’ve got a mill, hopefully you have a CNC and can cut more fin blanks. You’re not getting this right on the first try B) . But hey, maybe you blow through a few dozen and find a Whisper Fin or CG type breakthrough.

On the very bright side, testing fins is way more fun than testing boot releases

[Stevie Boy]

@dskunhardt Perhaps take a look at Hydrodynamics, not sure what benefits you would achieve on such a small area, I would think that you might get away with it on the thicker fins not so sure on the thinner ones, any groove could create a stress point, resulting in fin failure.

[ScottScott]

@aupatking The fin testing could result in some release testing however....

[ski6jones]

This could produce some content for the "Why I love the internet" thread. Video testing please.

[mike_mapple]

I did some fin testing with a lot of different things, cutting grooves being one, and I have to say I didnt use them but my dad and a few other skiers tried some for me, will be interesting to see what you think! let me know and we can compare notes!

[dskunhardt]

After all the research my first approach will be golf like dimple pattern. @mike_mapple For sure, I will be posting all my notes about it.

[BraceMaker]

Dont remember who came up with this back in what 2013 or 14? I set the fin down on an angle plate with double sided tape and milled 3 steps.

 

Zero observable change. If you are RFF and want to test it send me an address.

 

 

[BraceMaker]

Had photos of the set up with dykem and lay out but I am not going to pay photobucket to relive my misspent youth.

 

 

 

Just measured the thickness did trig to figure out the depth of cut and angle then used a sine plate to set it up on my mill and touched off manually at each step on the shallow side with a cigarette paper then milled the length on the X manually. Backed off and touched on the next one and repeated.

 

Again In think the idea is sound but Denali does this with their angle cut fin holes which reduce effective area with a lot less work and more repeatable outcome.

 

NOT my idea someone posted it and I tried it. Followed by whatever rum Horton then pedaled.

[ScottScott]

Be interesting to try the effect on one side or the other, but not both (or more effect on one side or the other) Texture will reduce drag, similar to what HO does with their ski bottom. Keep the video rolling.

[BraceMaker]

This was one side only being RFF the oringinator thought the steps would cause turbulence that would reduce the offside surface area.

 

If you recall washers under the finbox you will have the same idea.

[BraceMaker]

@AdamCord did you evaluate?

[DW]

Laminar flow along a surface has less drag than turbulent flow therefore tripping laminar flow along the fin surface can increase drag. A fin sees both laminar and turbulent flow along its surface, you can see that on an anodized fin which shows the effects of turbulent flow. Flow analysis on a ski in motion is quite complicated. Hence, experimentation is the current method to analyze the effects.

[Horton]

you guys don't forget that flex matters. when you start machining material away your fin is going to flex more. More fin flex is going to make the ski slower out of the ball, potentially more forgiving, and maybe hold more angle.

 

Slower and more angle may result in sore upper back.

 

If you guys are just bored and happy to burn boat gas on an experiment, rock on. If you're doing this because you think you're going to improve your skiing I find that dubious.

[Dirt]

I can’t remember who but years ago he was messing with fins made of carbon or balsa. He reminded me of pinky and the brain. Well…pinky not the brain.

 

The idea is good, the last guy whose name I can’t remember, not so good.

[dskunhardt]

The first prototype is ready. I won't be able to put it to the test until next week. I had some error with the setup on the CNC, but I will try it anyway.

 

I keep you posted on the results.

 

 

 

[jimbrake]

@dskunhardt - "the Titleist"

 

[igkya]

@dskunhardt You missed a spot

[Cent]

Wish you well with your testing. Let us know what it does.

[thager]

If you put it on a turntable and play it backwards it says "Wake Boarding rules"!

[Horton]

@dskunhardt are the dimples on both sides?

[BraceMaker]

@dskunhardt I do recall that mythbusters episode that concluded the dimples do indeed reduce drag.

[Than_Bogan]

Looking forward to hearing about it. I could imagine no effect or unskiable or awesome!

[Horton]

My purely unscientific guess is it will increase drag

[ALPJr]

The HO Syndicate team calls it ‘speed’ skin.

[aupatking]

As long as the video is shared with us.....

[swbca]

Remember the fin holes that used to make a whistling noise ? I think it was because the first do-it-yourself holes were smaller. The resulting harmony of holes would change pitch with speed. If those small holes were used today, the skier speed range at 41off could generate 3 or 4 octave's. On our lake we could hear fin whistling a 1/2 mile away.

 

I think the golf-ball textured fin will be silent and have less drag, but not as much affect as a couple of degrees of wing angle.

[papp101]

I have a small home CNC and think this project is awesome!!