EDIT: I’d say the change in surface, front and rear, is negligible. However, as with a triangle, a constant increase/relatively proportional distribution of width to length over the surface of the fin inproves structural strength and reduces flex. Reduced flex will change performance as lateral pressure is applied during a cutback.
Water and air are both fluids. Water is “liquid” air is “gaseous.” Check out Bernoulli’s principles regarding lift and differential pressure gradients.
To all, please feel free to disagree with or insult me. I really don’t give a sh!t.
No offense intended. I find it more productive to see rather than link what is being discussed:
“These are some of the Fin Templates i use I have ridden and worked with these for 25 years Several sizes to cover a wide range of boards
Top is a 7’ single fin Second row are Twin fin Templates Third row are rear 4 fin templates ranging from 3 3/4” to 4 7/16" Fourth and Fifth row are rear 5 fin templates ranging from 2 15/16 to 3 7/8" Bottom are my thruster templates fronts 4 5/8" , 4 1/2", 4 3/8" Rear templates 4 5/8" ,4 1/2" , 4 3/8" ,4 1/4"
This weeks batch of fins going out
Top row are rear 4 fins for Jason Second row is a 4 5/8" front 4 1/2" thruster set for John Hume Third row is a 4 5/8" thruster set for Gordon Forester in England Fourth row is a 4 1/2" set for Livingston Reed Fifth row is a 4 1/2" thruster set for Matt Barberi Sixth row is a 5 fin set for Herb Galang for his Roberts Diamond Fish. He has a thruster set already in his white diamond. Bottom row is a 4 5/8" set for Jim Dunlap in Florida
I am using cord length as a term to describe the width of the fin at at certain place on the fin.
Since you dont feel the area change is much between these 2 fins then we cant go much further
Read Dougs review and he states like most all that ride these after riding 20 + years of others something different is going on here.
Thats what that difference in front and rear is doing.
My template starts at a width then smoothly moves up and back into a higher pressure placement while reducing its width at a determined rate to release that pressure at a determined rate.
This template works as one surface gathering energy and releasing it immediately to move forward down the face slightly to the side running more water thru the fin constantly gaining speed.
There is slightly more surface area in your fin. This will create more resistance to lateral movement (more surface-greater side pressure from lateral movement). More base to height of each successive chord through the fin’s center will increase strength and decrease flex. Flex is recoil as in a spring. Less flex = more stored “energy.” “Release” and “drive” are subjective concepts/observations (anthropomorphic sensations) related to recoil, lift, drag and centripetal acceleration.
I'm skeptical of the "science" in surf design, I feel much more comfortable discussing what works for you, or your clients. I still think there is more art than science in surfboard design. If this fin design works for you, then it works. How do your riders, or yourself, describe the difference in the way their boards ride?
Is this a thruster fin, a fiver fin, or otherwise?
Clearly your customers can feel a difference in performance. While subjective, I’m sure it is discernible. The actual source/cause of difference may be complex and is likely multi-variate.
It isn’t critical to know the science. Gestalt is important too. If it is working and pleases your customers, keep doing it … continue to explore and adapt.
EDIT: I see Huckleberry made a similar comment while I was responding.
"Now available are my custom foiled G10 fins. I custom foil these to give different types of hold and flex. I prefer very stiff to get the most out of these templates. The added stiffness of G10 enhances the designed release of the template to retain the energy of the wave."
I'm guessing the stiffness is a big factor in the fins' different feel. This quote (above) from your website sounds much like Thrailkill's dictum flex = energy loss.
I am really intrigued by the five fin setup, would love to try one of those!
Tomo is a power surfer, rips for sure. Seems to me his fins have a lot of area, I'm guessing the main flex is in the large tips, but toward the base not so much, especially as he uses glass ons a lot. Meaning his fins may have as much "stiff" area as your fins, with the addition of a wide flexy tip.
At any rate, like you say, two different directions.
I'm always more intrigued by what works for the "average Joe" surfer, because high-performance guys like Tomo push their equipment way beyond what I ever would. I'm just a recreational surfer, and I can't ride the common thin, narrow boards, because I can't catch waves with them. And I don't push my equipment in g-force mid face hacks, etc. I'm not a longboarder per se, but I'm moving in that direction as I age, LOL.
still love my small tri set GG , work well in all my boards and insanely good in the round tail they were made for !!
my take on GG’s fins
all the drive you could want , sensitive , controlled release , they give when you need them to and hold when they should . the small tabs let me fine tune the board for the conditions .
thanks for coming around and discussing Greg... regarding that 7'2" that you posted, obviously, the tail is narrower than the board next to it. are the fins also smaller? is the 7'2" a step-up or minigun?
