There are so many fins but whats sort of effect do you get by moving the area of the fin from the base to the tip ?
My guess is that if you have two fins of the same area…
the fin with the greater area close to the base will
1/. turn faster
2/. have a greater drive and hold due to the water flow being cornered between the fin and hull.
Here is what I understand from it:
The area distribution is one way to balance between these two.
Thanks for that Hans. I’m thinking about the Hockey fins and other fins where the bulk of the area is at the top of the fin… They would get drive from the overall area and the big head but does the drive have a different feel ?
Also with the bigger top there’s more glass and therefore volume that I’m guessing that these style of fins are slower due to the displacement and form drag.
“make the tips thin and the ‘stalk’ part thin / narrow [? like the wavefin, pictured?] , for flex ” , is what I’d been told.
… hopefully , ’ IF ’ the forecast swell and offshores eventuates here , on thursday , I may get a chance to ride both a thruster AND a quad setup of my hockey stick fins [ that will be on two **completely different **boards , by the way …]
cheers
ben
Hi Ben, are you starting your Summer surf program ? How cold is the water ?
Check out the Square Cut Fin thread for something new i surfed today.
yeah , the ones I recently made for a west coast vicco kneelo , had the wide base like the c drive fcs fin you pictured , brett.
he was adamant that the wider base had produced drive and hold , and that the flex had produced á lively 'feel . He wanted them EXTREMELY thin …so , hope he hasn’t snapped them all on his first turn ?! I made HIM a thruster set , and his mate wanted a quad set [which I made a bit thicker.
took a LOT of time to cut out and foil .
The ones I made for myself , have a much shorter base , more like the ‘wavefins’ winged fins we have. A mate , Dumpy, has the wavefin , at the moment . But is awaiting a hip operation , unfortunately , so …new test pilot needed [? me?] .
cheers
ben
'around maybe 17 degrees ’ , I heard
depending largely , of course , on the absence of the usual 5-10 degrees windchill
"
… oh well
Standard fin
Wide base
Area narrowing and moving forward
Area then moving rearward and increasing in width.
My fin design works as one area reducing as it moves up and back
Wow, thats a work of art Greg.
Greg, That fin outline and foil are amazing.
My view is that the water runs from the leading to the trailing edge so the area distribution from front to back is just as important.
Looking at a lot of outlines shows how similar fins are. All the leading edge curves are so similar resulting in a common feel for the rider. And plotting the area distribution from front to back results in a similar set of figures for almost all fins. There’s a strong area increase to a maximum followed by a sharp drop. This would mimic the favourable bio-mechanics of a turn where hold would quickly increase into a turn but reduce even quicker to allow the board to pivot rather than track.
Widest at the base closest to being part of the board .
Back edge moving upward and back .
Leading edge curve designed with trailing edge curve to reduce area as it moves upward and back reducing pressure as the surface area moves to the higher pressure - back and deeper position .
Never moving forward then back like most “designs” :-)
I made a 9’, low rocker, narrow pin tail, single fin, with a fin I made like the Greenough stage 6. There was probably a picture, but I think it was lost in the switch over.
9" deep, oak, stainless steel, carbonfiber, glass, and epoxy. @ 15 degrees rake, 1 1/2" wide “stock”, @ 4"X4" paddle/head.
All I can tell you about it is this: that fin held in the tube/foam ball/white water, better than anything I’ve ever ridden.
The theory (All this was by way of inspiration from Dale Solomonson) goes - having that fin area down in the “clean” water, as opposed to the turbulance of the white water effected surface water will provide superior hold.
Great work Greg awesome foils and design, really like to try some of your fins someday, able to ship some down to N.Z ?
Greg, interestingly your fin outline is where I think there’s room for improvement by moving more area into the mid area of a fin, it doesn’t affect the base length but puts the ‘Drive’ component closer to the board where the Drive is more effective.
If you can get more drive from positioning the area lower then the tip can be more upright for better pivot.
But the leading edge curve needs to stay fairly constant to make it rider friendly.
I’d like to see a fin with a higher / fuller reverse trailing edge.
the ‘Drive’ component closer to the board where the Drive is more effective.
Is this assertion based on the structural/physical interaction of the fin base and the bottom of the board?
I love this subject, because, like most board design, most fins are basically the same… I also appreciate Greg’s work with keeping fins and boards a simple unified functioning whole.
I ship fins everywhere 
C- drive is as far away from my concept and function as you can get .
You have a strip of area about 1" tall as the base then a small narrow raked fin with a tip that grows in area mounted on the front of that base .
My fins feel like wings lifting ,planing and releasing with their smooth designed in loss of area from base to tip . C- drive is a rudder like many other designs posted above.
