*** Official Fin Thread ***

need 4 speed

Phil Edwards status
Nov 1, 2003
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but I think cant makes more sense as a benefit to twins.
In what way?(on a quest for knowledge)
Question(s):
Cant creates lift and promotes turning on rail
Toe promotes turning by increasing AOA
How much of this is the right amount? on twin in particular with lack of center stabilizer
Not really interested in keels, they lack toe and cant for drive and their short length promotes turning. (Its not the 70's)
I currently run app. 4° of cant and 1/16-3/16" of toe (settling in around an 1/8) I'd go 3° ,but its tough making 5°Fusions roll up that much
 

sushipop

Michael Peterson status
Feb 7, 2008
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The Dagobah System
I was thinking of it in terms of the extra surface area of the twin—when toed in too much might cause drag. Also, since twins can get squirrelly (if you’re not using the now now fin placement) then leaving them less toed could help with drive and stability. Same as you, I was thinking cant would help with lift and rail to rail transition to keep the board maneuverable. But honestly, I am not by any means experienced on this stuff.
 
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silentbutdeadly

Duke status
Sep 26, 2005
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Tower 13
I'm finding the fins with more can't have better rail to rail but I also have more episodes of the fins not engaging or staying engaged as much as I'd like. I don't know if that's the cant or the template.
 
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need 4 speed

Phil Edwards status
Nov 1, 2003
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@silentbutdeadly
My guess is a product of a couple things, sort working together or not.
I've tuned my boards to where they suit my style and feel I'm looking for
Got a lot of advise from @ghostshaper @retodd and @griffinsurfboard to get where I am (some experimenting too) making fins myself opened up opportunities. Fun to nerd out on surfboards and ride what you make yourself
 
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silentbutdeadly

Duke status
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absolutely. I admire people like yourself that can do that. I've actually been going back and forth with Tim on templates and little tweaks. we're working on dialing things in as I type this. So fun.

Unfortunately I don't have an ounce of talent for doing anything with my hands so I leave it to the experts.
 
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griffinsurfboard

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Oct 31, 2004
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To a certain amount more a canted - tilted fin releases pressure = less resistance , feels smaller

More upright holds more , more directional , feels full size

10 degree tilt with little toe in creates something Very Special
Little toe in puts the pressure back onto the fin the increased tilt reduces
The increased tilt makes fin become winglike in the face - amazing stuff happens
 

silentbutdeadly

Duke status
Sep 26, 2005
33,488
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Tower 13
To a certain amount more a canted - tilted fin releases pressure = less resistance , feels smaller

More upright holds more , more directional , feels full size

10 degree tilt with little toe in creates something Very Special
Little toe in puts the pressure back onto the fin the increased tilt reduces
The increased tilt makes fin become winglike in the face - amazing stuff happens
awesome. Thanks

next step is to take some base out of EN's. we'll see how it goes.
 

need 4 speed

Phil Edwards status
Nov 1, 2003
6,676
3,579
113
SoCal
To a certain amount more a canted - tilted fin releases pressure = less resistance , feels smaller

More upright holds more , more directional , feels full size

10 degree tilt with little toe in creates something Very Special
Little toe in puts the pressure back onto the fin the increased tilt reduces
The increased tilt makes fin become winglike in the face - amazing stuff happens
Is this an experimentation I should explore? "please quantify "little toe" if you would
I have a board I can experiment with (ie reroute boxes)

@silentbutdeadly "next step is to take some base out of EN's. we'll see how it goes"
maybe consider taking a little tip area out instead of messing with the base
 
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oeste858

Phil Edwards status
Sep 11, 2017
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With so many factors in fins (such as template, size, cant, toe), it can be hard for many of us to decipher which aspect is causing a particular effect we may notice.
Thanks GG & retodd. Your comments make sense, specifically when I think about my experience riding an extreme example: minisims with dual keels (or halfmoon) fins with zero or almost no cant nor toe. Absolutely fly down the line.
 

tom@daumtooling

Michael Peterson status
Jan 10, 2002
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With so many factors in fins (such as template, size, cant, toe), it can be hard for many of us to decipher which aspect is causing a particular effect we may notice.
Thanks GG & retodd. Your comments make sense, specifically when I think about my experience riding an extreme example: minisims with dual keels (or halfmoon) fins with zero or almost no cant nor toe. Absolutely fly down the line.
A while back I wrote this mini article;
When you walk into your favorite surf shop and get all google eyed over the masterpieces in the racks, it’s not the fins you’re drooling over. Think about it for a minute though. What is a surfboard, but a summation of hydrodynamic surfaces. Just as an airplane generates lift from its wings and control from its tail; your board’s bottom generates lift and affects speed. But, it’s your fins working together with rail and bottom contour that most influence the feel of your board when turning. And let’s face it how many short boarders straight-line the waves they ride.
Few surfers really understand how fins affect the way their board rides and leave all the specifics to someone else. Rail and bottom contour assist fins in performing their function. But, what really influences the way your board turns is the combination of several important fin factors. No wonder so few surfers pay attention to the "Fin Affect". It’s f’n complicated!
But, today, as the form shape of surfboards goes through finer and finer adjustments, the biggest gains you can make to your board’s performance have to do with your fins. The predominant factors that influence your "Fin Affect" are:
1) Foil Shape- the curvature from leading edge to trailing edge as it changes from base to tip.
2) Template shape- The combination of depth, width, and rake that make up the profile outline of the fin.
3) Placement- which incorporates how far the fins are from the back of the board, how far apart they are from one another, toe and camber.
4) Stability and flex.

Let’s discuss each of these and how changing them will affect the way your board performs.
Foils are surfaces that affect lift and drag. If you notice an airplane wing has a flat side on the bottom and curved side on the top. The path of least resistance is the bottom side. It takes more effort (drag) to flow around the curved top surface, so more air flows under the wing than over. This creates high pressure under the wing. The air that does flow over the wing separates from the wing at the apex of the leading edge of the wing and creates a low-pressure area above the foil and a higher pressure area below. This difference in pressure forms the force (lift) that allows the wing to go up. The more curve a foil has the more drag it induces over the curved surface; which means that a foil with greater curvature will have more lift at lower speeds. The problem is that at higher speeds that additional drag will develop turbulence and stall the flow across the foil. The exact same scenario occurs under water with side fins. The big difference is that instead of lifting your tail out under water; Side fins orient the curved surface so that they actually pull your boards fin and rail down into the water. This gives you hold when cranking a nasty slash. Consequently, thicker more curvy foils for slow waves and flatter more fine foils for high-speed waves.
Template shape has to do with how the fin looks in profile. An over simplification would be deeper, rakier & wider fins provide more control. But, the more profile you have the more fin you drag around. So, you have to optimize the combination of the three so that it is loose enough for your conditions. Yet, it is also tight enough to not get too squirrelly on you. Other factors that figure into requiring more or less of these three variables are:
1) Type of wave: steep and heavy or slopey and fun.
2) Surface conditions: Choppy and irregular or clean and smooth.
3) Rider Size: Big and heavy or small and featherweight.
4) Rider Style: Subtle and flowing or Extreme and radical.


Each of the first considerations requires more fin template area and each of the second work better with less.







Placement has traditionally been left to convention. Simon Anderson set a benchmark twenty years ago for approximate location. Each shaper has their own personal preference for each of the "models" they make. But, there are subtle differences in most boards and in all riders. Otherwise why would custom boards be in such demand?
And remarkably as little as an 1/8" movement fore or aft in either or both the center fin or the side fins can have almost as much effect as going from a rakey 4 ¾" fin to a vertical 4 5/8" fin. If you move your fins closer together they act looser and if you spread them further apart they get tighter.
Toe is the amount of angle the base of your side fins are pointed in towards the center of the board relative to the leading edge and trailing edge at the base. Camber is the amount of angle the body of your fin is set at relative to an imaginary horizontal plane perpendicular to your stringer. Both affect the angle of attack that your fin foils experience as they flow through the water. More angle forces more water flow around the outside plane at lower speeds. The net affect is that it becomes easier to initiate turns on slower waves. To much angle at higher speeds increases turbulence and drag.
Finally, stability and flex are crucial to making this all click. If you have a deeper fin you can get away with more tip-flex and not wash out. The benefit of tip flex is that it dampens or smoothes out some of the bite in direction changes. The down side of tip flex is that if you get too much tip flex it will wash out. Base stability is crucial to a good set of fins. If a fin moves around at the base it will set up turbulence. Turbulence generates drag and disturbs the lift, which keeps you fins holding. So it is slow and out of control. If you like a more pivoty board you would do well to try a stiffer set of smaller more vertical fins.
Prior to eight years ago the only options a surfer had to muck with all these variables was to grind his glass-on fins off and install a slightly different set in a slightly different location and record the differences until they found the optimum. Not very likely. So, with the exception of a few elite pros, we all lived with what we were given. Now with the advent of removable fins (i.e. FCS, Future, LokBox, OAM and O’Fish’l) you can at least muck with the first two "Fin affect factors". But, if you want the ability to dial in your board with all four factors you have got to try the newest competitor to the fin system market Red X.
Tom O’Keefe
 

sdsrfr

Phil Edwards status
Jul 13, 2020
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San Diego
Son of Cobra twins are 7.5deg according to the Futures website, and other twins made by Futures are 4deg(?) per the SoC description.

Pretty positive True Ames twins have more, at least my Hobie keel set does. Not sure what Captain Fin Co does on their twins by default.

how much cant are in the AMT set?

@Duffy LaCoronilla i think you own both AMT and SOC sets and could quickly compare....
 
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Duffy LaCoronilla

Duke status
Apr 27, 2016
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Son of Cobra twins are 7.5deg according to the Futures website, and other twins made by Futures are 4deg(?) per the SoC description.

Pretty positive True Ames twins have more, at least my Hobie keel set does. Not sure what Captain Fin Co does on their twins by default.

how much cant are in the AMT set?

@Duffy LaCoronilla i think you own both AMT and SOC sets and could quickly compare....
I don’t have a protractor handy but using the eyeball method they both appear to have about 7.5 degrees of cant (3.25 degrees Hawaiian scale).
 

sdsrfr

Phil Edwards status
Jul 13, 2020
5,857
11,266
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San Diego
:cheers:

lol, yeah, that's probably the same way I've been measuring mine against one another. Lay them flat, push down on the base, and see if the tips align or not...
 
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