Designing Fins.

Everyones wanted to make a finup with their own fin desigcan it be ?

I suppose the first thing to do would be whole lot of fins, Google, ride them, ruminate over the difference in perforwatching YouTshow fins behave and there’s always oceans of Hydrodyna and theosorb.

 

welcome back !

 

  WHERE have you been ?

 

  … making fins ?  hydrofoiling ?   boards ?

Guys like GG have made a science of fin design / placement.  My hat’s off to guys like that.

I’ve made several fins, always of my “own design” (meaning I draw it myself, but clearly a copy of other fins I have seen), but not as technical or analytical as you.  I just look at fins, draw up some sketches, arrive at a design that looks good to me, draw it up, cut it out, and foil to the best of my ability.  I’m just a hobbyist builder, no fin designer really, but I don’t let that stop me from drawing and building my own fins.  All of my fins have worked well enough for me, a recreational surfer.  Your creative / analytical mindset would likely yield a more original design than I could come up with!

 

@ Huck, same for pro, hobbyists or complete newbie, somewhere in the back of their head is a door and behind that is a another door that leads to a bar where new ideas are formed. I was interested in finding out if it’s inspiration, perspiration or random luck that makes ‘design’ happen.

@ Ben.  A bit from Column A, a bit from Column B…

How about you Ben, still making fins ?

I thought this topic would be good for all the people who build fins to discuss how they came up with the design.

Inspired by the History of Fins thread,  I wondered how people actually come up with the intellecual concept of a new Fin… Did they just copy a standard shape, modify an existing template or create their own ?

 

.

Similar to surfboard template design .

Function of area .

What was wrong with that reply? GG copped two negative votes for it. How come? Seems like a perfectly reasonable answer as to the primary factor he considers in how he designs fins.

Nice-looking fins there Huck.

Full marks on the construction and joinery demonstrated in them.

As regards to the design side; if you’re happy with the way they’re peforming for you, then you’ve done well enough on that side of things.

Don’t write yourself off Huck; you and the other mod’s have to demonstrate a fair bit of creativity and analysis of situations in how you manage and deal with users to moderate the forums in order to keep Sways on a more or less even keel. And you’ve collectively managed to successfully do that for a long time now.

Cool topic.  Long story long…I didn’t design the template but worked with the designer Mike Black.  He wanted a fin made and I helped as much as I could.  He designed it from a different angle and one that he is passionate about.  Math!  He is stoked on the fin and so are others.

Here is what he writes about coming up with the template.

Size: 8’’ deep 10.5’’ base

As the name suggest, this fin is built using a mathematical algorithm. Mathematically modeling nature was the inspiration. I built a golden ratio spiral up to the 8th number (1,1,2,3,5,8,13,21). I drew a radius 21 units wide, then I went in and up 8 units from the arc. I used that as the center of my next arc that was again a radius of 21 units.

This fin has a tremendous amount of drive and it has a tight turning radius when one commits the rail on a top turn as well as projects off the bottom. Although this fin has a .807 to 1 height to base ratio, the fin has never spun out on me while nose riding. This fin features the Kumano Fin System bearings instead of the traditional screw and plate. By eliminating the screw and plate I am able to place the fin closer to the tail where these fins belong. 

– Mike Black

started out like this

I recently had a another shaper call to get wooden nose and tail blocks made and installed, plus the customer wanted a wood fin. Customer sends me a pic on my phone of the fin template he wanted, it was on the phone 1-1/2" tall and his order called for 9-1/2". Long before this I regretted being such a slacker in Mrs. Sugino’s algebra and geometry classes in Hawaii. After a bit of head scratching, I came up with the correct ratio, 6.333, measured carefully the base, rake and got it to look like the tiny image. He called to say he’ll be using me again, no thanks!  And he wanted the glass on to be 11" from the tail !!!

Fibonacci spiral.       Found throughout nature.

Which approximates the “Golden Spiral.”

Just a contribution to your point, not a challenge.

Which has nothing to do with riding a wave .

Not a challenge .

Lets discuss the use and functions of area in a fin . 

 

If you want to compare the differences of the fin outline, you can start by tracing your favorite fins in finFoil. Then modify the outline. And as a last step scale the fin by it’s depth to get the same area as the original fin.

Area is a very important factor, but very difficult to compare without software.

Hi Hans, I just got a new laptop so after the usual setup routine I’m downloading your free Finfoil program. Thanks for doing so much work on it, it’s just amazing.

Like your program - good fun .

Back to this :  

discuss the use and functions of area in a fin  :-)

Dave, that flow-thru in Volan is an amazing design.

Even as a single fin, something like that is appealing and the design makes me want to ride one just to find out how it works, how good it is in all sorts of waves. It’s quite a piece of art just to look at !

 


I believe that area should be the main parameter to characterise fins.

It’s like volume for boards.

In the early years of windsurfing boards were mainly compared by their length (like surfing). Around the year 2000 this changed to comparing volume, and now windsurfers are talking about their board’s volume.

With fins, we are still mainly comparing depth, and this should change. Length is still a somewhat valid characteristic parameter if the same fin-style is compared, but doesn’t allow to compare significantly different shapes. e.g. In windsurfing a ~20cm freestyle fin, can hold the same sail as a ~35cm slalom fin, while the areas are equal.

Sails (airfoils) are all compared by area, time to start doing this with our fins (hydrofoils) too.

Its all about Size .

No its not , I give up .   :slight_smile:

WSubject