Slightly uneven fin foil. big deal?

Ahoy Swaylockians,  So i am foiling an 7.75 singlefin for a 6’8 shortboard.  The fin is 9/16 thick.  The foil is a tiny bit rounder on the leading edge of the fin than the other side.  Will this slight difference in foil on the one side of the fin negatively affect the way the board rides?  Thanks guys!

just to clarify, one side of the leading edge is slightly rounder than the other side of the leading edge.  The trailing foil is pretty even in my opinion.


Hey Chrisp, I will upload some pics soon hopefully but the uneveness probably wont even be perceptible in a photo.  it is pretty slight but I thought I would post because I didnt find anything that answered this particulr question in the forums.  

At a high speed, and a high AoA, there is most likely a difference going left or right, but I don’t believe it would be perceptable to you.     Negative effect?      Probably not.

Without pics difficult to say.

But the good news is: the leading edge is far less important than the trailing edge.

You’ll probably not notice the difference.

Cool sounds good guys. should be fine.  cant wait to glass it up!



Why don’t you just take a little more off of the rounder side?

Wait a minute, I just reread the question

What do you mean by the other side? The opposite of leading edge is trailing edge. And you definately want the trailing edge sharper than the leading edge.

I hope you are meaning the other side of the profile, along the width of the fin, close to the leading edge.

Hi Surfer O-

The enclosed NACA 0012-0014-0016 picture is over in Swaypedia. Leading edge is at 0.0, trailing edge is at 1.0 

Is it that you leading edge sides are different, or that leading edge is different than trailing?

If you can post some pics you’ll get a quicker (and maybe more brutally honest) answer.

Are you making a glass-on or one that goes in a box?



What Surfifty said.  Why don’t you just fix it?

Hey guys,  Just to clarify, one of the leading sides was slightly rounder than the other leading side.  The trailing foil on both sides appears to be even.  I didnt originally want to fix it because the rounder side of the Leading edge was the orignal shape I was going for.  I removed more material from this side the other day and now it is very even.  Looks Pretty good to me.  Thanks for the help eveyone.  Gene, I watched The VISSLA video of you making a redwood/glass fin for the 60’s style gun.  Aweome stuff.  I am going to attach my fin to a temporary base like you did in the video.  I am going to try and add a glass bead around the fin while it is on this temporary base by sandwhiching the saturated roving in between 1 layer of glass for each side of fin.  I will then cut the fin off the temporary base and cut off the excess I left at bottom of the fin.  It is going to be a glass on.  will post pics soon.  I dont have an Iphone so i need to remember to bring a camera to my shop.

You know… Just consider the possible benefits of a different foil on each side including the leading edge. 

Sure every side fin is already differently foiled but think of the possibilities for single fins or centre fins. Think how differently surfers attack fore and backhand waves. You could even make a left hand wave fin for goofy surfers and one for natural. 

Talking about assymetrical single fins:

Fins for breaking the windsurfing speed record are assymetrical and used in a single fin setup. This gives the highest lift/drag ratio and allows a lower angle of attack. Altough only in one direction (not the band).

In the other direction, they are good enough to get you back to the beginning of the speed strip.

Hi Hans, I’ve been a windsurfer since the early 80’s, maybe I’ve seen the idea before and forgot it, even Roy just thought of it too. He’s quite a mobile thinker. Dunno how he keeps going.

Exactly the case with my ‘‘Twingle’’ fin setup.     Pop one fin out, and you have not only an asymmetricaly foiled single fin, but asymmetrical fin placement as well.     Think about it.

In windsurfing they are only a very recent development, to try to reach the 100km/h milestone.

Hans, I took the concept of a flexible hull to a windsurfer back in the 90’s by hollowing out the middle of the hull and making it an inflatable like a Surfmat. Very smooth, fast, a little loss of directional control. The current speed guys do everything but with a solid hull. I’ve told them about a flexible hull but they’re not interested. 

Having a hard front rocker slows any craft by the degree that it moves forward. The slater Genie Boot is an obvious example.