Some fins I took pictures of this week. Dolphins, right whales, orcas, and hammerhead sharks. I rotated them to make them shape-comparable. They all have aspect ratios close to 1 and rakes close to surfboard fins. Enjoy and discuss.
I’m liking the Orca as a big 'ol glassed on single for a noserider… 
And one not so raked and with a higher aspect ratio:
Raked and high aspect ratio:
different strokes for different fish ?
Not to forget horizontal flukes… . . they are not all vertical fins:
Marine Biology 101:
Comparing a static foil (surfboard fin) to a dynamic system (animal fins)
is not productive venture. Shark & whale (& dolphin) fins have bones & cartilage
as a base with flexible muscle that allows the animal to modify the shape, foil & rake.
Also, micro-muscles in the skin create variable drag surfaces. I could go on…
Make a fin that does all that and you’ll put Merrick et. al. out of business…
We already have flexible boards with flexible fins ridden by flexible riders. . … … better update your schoolbooks ‘teach’ !
Make a better fin and you will go faster. . … . we are already doing that too .
The discussion is supposed to be about aspect ratios and the rake of the leading edge, comparing fins used in nature with man made fins. . … or something like that . . … now don’t tell us that it’s an entirely unproductive venture because it isn’t
BTW your assumption that the goal of analysing fins is to put other people out of business means to me that you haven’t found the plot yet. . . what a jaded way to look at it, this thread has a lot of potential for fun and learning. . . . don’t you think ‘Teach’ ?
Your post gets a Bullshit rating of 8/10 that’s a pass with BS merit.
:})
AHA! Finally somebody gets the fin thing right. Good job, Dave.
ST, all respect for your degree, however
LOL I think it has been and continues to be a highly productive and profitable venture. Look around. And I daresay Blakestah will be along shortly to tell you about the latest productive iterations of his particular translation
The sub-dermal micromuscular thing is happening in the main fuselage, I think a Marine Biology 101 prof would tell you, not on the pectoral fin surfaces, or even in the tail or tail fins. Those are using macromuscular dynamics and firm control surfaces – I think/see that the dermis is fairly taught on those surfaces
Again, ignorance rears its ugly head.
I don’t want to get into a pissing contest Tom,
but to clarify I didn’t say anything about flexible.
(or parabolic either) I said dynamic. Look up the meaning
the same way you chastise others to do.
A dynamic biological system is multivariable, not just on
a few parameters such as your fins/boards. If your fins were
computer controlled internally and externally they might approach
the interaction of a shark pectoral fin on a shark’s bad day.
Not to put down what you do, but just looking at something in
Nature without understanding how it works in totality is IMHO
A waste of time. I didn’t refer to analysis of surfboard fins as
A waste of time. Read my post again………
And speaking of BS, I have never ragged on your posts regardless
On how useless I found them…….
Janklow: I am a prof. and you don’t know what the latest
research is so read the post again!!! Dynamic is the key word
here (the correct word in your post is taut, as in tight)
and I’m not knocking anybody’s surfboard fin research/design,
Just the comparison to living biology……
For what it’s worth I swear by speeddialers for full figured fish boards.
…some Tuna fishes has fins that when they dont use them, put em totally flat and hidden in the back…
good for some futuristic board tricks…
Ouch. Ignorance, eh.
Lemme see if I got you right here: " Marine Biology 101:
Comparing a static foil (surfboard fin) to a dynamic system (animal fins)
is not productive venture (sic). Shark & whale (& dolphin) fins have bones & cartilage
as a base with flexible muscle that allows the animal to modify the shape, foil & rake.
Also, micro-muscles in the skin create variable drag surfaces. I could go on…
Make a fin that does all that and you’ll put Merrick et. al. out of business… . "
Nobody would say that there isn’t a heap more happening on a dolphin’s fin, but nobody would or could look at it and say that it wasn’t more a question of number of controllable dynamic factors than an outright red herring, so to speak.
Taut. Right. I had that, but I fucked it up somewhere in there. I didn’t realize we were being graded on spelling or grammar. Pedant much?
Whenever you ladies are done…
I was at the Monterey Aquarium at a stop over on a bike ride down the coast I was on. Regretfully, I had to make it to the north side of big sur and only got a chance to spend a few hours at the most amazing aquarium I have ever had the chance to go to. One thing that did fall in my slot was the feeding at the outer bay tank. All open ocean pelagics and the such, yellowfin, bluefin, sunfish, dorado… the feeding was intense. Watching th dorado “flash” was cool, but the most amazing was the retractable fins in front of the dorsal fins on the tuna. Watching them go from 5 to 40 mph was cool, but seeing the fins drop in appearing “seamless” was pretty rad. Had the wheels turning looking at tuna fin rake and the such…
Ive heard of some footage from Greenough of tuna and dolphins, surfing and swimming…
Would I be throwing myself under the bus, if I said that if GG thinks open ocean swimming species as inspiration, maybe theres more there going on than a nice outline.
thank you blakestah for bringing this up and thank you tombloke and surfteach for your (in my view) radical positions because they really create an inspiring room for thinking.
i´d like to share some of it: i think even if watercreatures can alter the shape of their fins, natures evolutionary achieved efficiency would suggest that there has to be a normal effortless shape perfectly designed for a general purpose. if so it would be most interesting to know about this general purpose, as there are fins creating forward drive in a pendular motion, fins more for stability, fins for fine steering adjustments and whatever man doesn´t know of yet.
eventhough i have the feeling that the stabilityfins came closest to the purpose of surfboardfins and eventhough i´d figure stabilityfins to be the least dynamic ones i got hooked on the idea of a fin which mechanically changes it´s flexibility in respond to flexing forces on itself.
this thought must seem to be nebulous and speculative up to this point, but here it clears up:
keltic warriers had a sophisticated chain for attachment of their swords to their belts. the chain was blacksmithed in a way, that it would stiffen under torsionforces, enabeling the warrior to run faster without getting the sword in the way.
don´t ask me about the exact design of the chainelements because all i know about it comes from a tv-documentary on recent findings in northern italy.
may this also inspire you to design a halfway dynamic fin!
greetings - d.
Quote:
Marine Biology 101:Comparing a static foil (surfboard fin) to a dynamic system (animal fins)
is not productive venture. Shark & whale (& dolphin) fins have bones & cartilage
as a base with flexible muscle that allows the animal to modify the shape, foil & rake.
Also, micro-muscles in the skin create variable drag surfaces. I could go on…
Make a fin that does all that and you’ll put Merrick et. al. out of business…
Changes in foil are not substantial with the fins that have been evaluated. There’s a good paper on the leopard shark’s pectoral fins movements in a flow tank.
http://jeb.biologists.org/cgi/content/abstract/203/15/2261
The fin is subtlely concave on the high pressure side when generating lift, and flat/assymmetric when generating negative lift.
They do change substantially in AOA, something like ± 12 degrees. Someone has already made fins that dynamically change in AOA at the base.
And changes in rake appear non-advantageous for surfing, and also not substantial in dolphin/shark pectorals.
But there is still much to be appreciated about rake and changes in chord length vs depth from studying nature’s pectoral fins. The biggest advancements in fin planshape came in the 1960s from modelling a surfboard fin after a dolphin fin.
A professorial appointment doesn’t relieve you of the need to use logic instead of appeals to authority in your arguments - quite the opposite. Your job is to make it understandable.
Al Merrick didn’t get where he is because of fin expertise.
Quote:
…some Tuna fishes has fins that when they dont use them, put em totally flat and hidden in the back…
good for some futuristic board tricks…
The old school tuna designs are classics forever. Who can forget this one.
Quote:
I said dynamic. Look up the meaning
the same way you chastise others to do.
A dynamic biological system is multivariable, not just on
a few parameters such as your fins/boards.
Dynamics: dy·nam·ics (d
-n
m
ks) n. 1. a. (used with a sing. verb) The branch of mechanics that is concerned with the effects of forces on the motion of a body or system of bodies, especially of forces that do not originate within the system itself. Also called kinetics. b. (used with a pl. verb) The forces and motions that characterize a system: The dynamics of ocean waves are complex.
Dynamics by definition includes the study of flexible boards, surfers, and fins in interaction with waves.
Clearly the study of marine animals has led to more dynamic surfboards and fins Multivariable, by the way, means more than one variable, so a surfing setup which flexes in two direction is multivariable
Next !
Quote:
If your fins were
computer controlled internally and externally they might approach
the interaction of a shark pectoral fin on a shark’s bad day.
My fins do better than that they are controlled by a finely tuned human brain. . . designed by one too !
By the way I wasn’t just referring to my fins and boards, there are lots of boardsout there which flex, and there are lots of fins which flex. … and then there are Blakestah’s dynamic surfing trux, and rotating fins, not to mention tinkler tails, soft boards like boogie boards, and of course Dale Solomonson’s mats, which are probably the most dynamic of all.
Also note that I didn’t say that my flexible boards and fins are as efficient as a shark body. … . the point was that by studying those animals we can sometimes learn from them and get a little closer to their level of efficiency.
No need to start arguing with something I didn’t say, that’s a no-no in the book of logical skullduggery in argument.
Minus 50 Gazillion marks, dunce cap for eternity (squared) hehehehe
[=1]
Quote:
[ 3][/]Not to put down what you do, but just looking at something in[/]
Nature without understanding how it works in totality is IMHO
A waste of time.
You imply that I just look at something without understanding it ?
It’s like this: I look at something, then I think about how it works then I look at it again, then I think about it some more, then I maybe go and read something relevant about it, then i think some more, then I visualise variations which can be applied to surfboards, then I go through a long thought process involving imagining the behaviour of the various variations in a variety of surfing sitauations, then sometimes run some calculations and comparisons with previous designs
This process has gone on continually for decades… . . it hardly ever stops, even when I sleep.
Today I designed flexible parabolic planshape cutaway keelfins with mini vortex generators, and started building them. . . the latest result from my efforts combined with fin research seen here on Swaylock’s. … . just another day in the think tank. . .
In other words you got it wrong minus a Brazillion points for you
Quote:
I didn’t refer to analysis of surfboard fins as
A waste of time. [=1][ 3][/]
We are in agreement here, I didn’t ever say that you had. . . . it was analysis of marine animals as a basis for fin design which you described as a waste of time.
That was a foul, you can’t catch me out by attributing arguments to me which I did not make.
[/]
[=1]
Quote:
[ 3][/]and I’m not knocking anybody’s surfboard fin research/design,[/]
Just the comparison to living biology……
For what it’s worth I swear by speeddialers for full figured fish boards.
FISH boards ???
Come now sir, that’s a biological heist there isn’t it ?
And speeddialer. … .? care to back THAT one up by any chance,?. . . definitely fast i’m sure (rolls eyeballs, purely for exercise)
Torturing Profs and lecturers who can’t cut it is an old sport of mine, they used to call me Roy the Terrible, sometimes I used to take over the class
Another favourite is rolling blackbelts in the dust. . . .
CHEEERs !
Good stuff, Dave. I didn’t realize the dolphin fin had been modeled–I had been thinking the current state of templates was just incrementally arrived at from Greenough.
RS,
I think you could ease up just a hair, although I understand whence the irritation you lay down herein above, bro.
I would enjoy seeing that last bit.
Yr F,
greg
Quote:
Good stuff, Dave. I didn't realize the dolphin fin had been modeled--I had been thinking the current state of templates was just incrementally arrived at from Greenough.
Greenough was a key player. The key player.
It was mostly D fins in the early 60s. All “dolphin”-style fins by mid 60s. Its fun talking to 70 yr old lifetime shapers. They can ID the years the fins were D fins made of wood (and tell you they were lammed with 2 layers of 10 oz Volan on each side, followed by fin rope on leading/trailing edge) - I think it was 61-2. Then 62-4 it was fiberglass D fins (still unfoiled). Then dolphin fins took over.
If you go ride D fin longboards and then try a dolphin fin, it is a HUGE step forward.
Greenough was inspired by a blue-fin tuna, though, I think. But the common longboard fins were called dolphin fins and shaped like the pic…
I know I’ve seen that before about the tuna and GG, but
TSJ vol 7 #4 (article on Greenough): “…I made this balsa kneeboard in wood shop at school in 1959…Originally, it had a fin similar to what they were using on conventional stand-up boards at the time. I eventually designed the one you see here, which was the first flexible, high aspect ratio fin I tried. It was based on a dolphin’s dorsal fin, and it made an unbelievable improvement to the speed and handling of the board. The fin moved with the water flow, so it never cavitated or stuck in a track. The success of that first fin influenced everything I’ve designed since.”
(pic is of the Velo and basically the fin you’re familiar with on it AFAICT)
I really don’t have time to defend myself from posts that are veiled attacks as I have too many boards to shape and classes to teach, but for the last time, I’ll make some
comments and apologize if they sound too “educational”……….
Roy, I said dynamic (adj.) not dynamics (n.)………… glad you know how to use
Wankerpedia……. and there is no such number as gazillion…………
Also, a biological feature such as a fin is a part of a whole and is affected by biological
forces such as behavior, reproduction, etc. that are not quantitative by nature but are
part of the equation in their evolution. Example: the post of the humpback pectoral fin
whose shape has more to do with behavior/reproduction than hydrodynamics….
Again, I was referring to the pics of the original post with my comments before Roy
Blindsided me with his negative comments………
AC: Glad you liked the Monterey Aquarium, hope you got to see the great white……
Be sure to check out the Steinhart in SF……
Blakestah:
Good comments on the leopard shark stuff and the other fin stuff too. My point was
that people like you who design interesting fin shapes/systems are using more flow
dynamics and physics to try and improve/invent new stuff for surfing. Biological systems can be inspiring sure
(I was at Rincon and saw GG surf that first winter and immediately went home and failed miserably in trying to make a spoon) but there is more going on. As far as changing rake of pectorals goes, sharks do that by altering the orientation of the fin to the body as in a high speed turn. (there is some good videos
of makos pursuing a trolled fish and making hard banking full speed turns and changing pectoral rake)
What I meant with my Merrick comment is that a new surfing invention can put an established icon brand out
of business as happened to lots during the shortboard revolution and we might see that someday…
I’m done & out…
IMHO surfboard fins serve much like underwater sails a sort stationary propeller if you will. Fins can create too much drag or not enough. They can be too engaged or too washy. The right balance of a single or fin combination for a given board foil is the aim in fin choice. Each sea creater make his living differently as so has become conformed to accomplish it by the natural process we are all a part of. The evolution of surfboards and surfboard fins is a similar process. At times I feel I am in control my process in this realm. Other times I let go and just surf, watch what’s around me and listen to my mentors. Then go and fashion something new and thereby learn another small lesson.
Man’s great creations are all ones that imitate the visions he takes from this majestic living world. The fins we humans place on our surfboards can never have the dynamic, living, metamorphic quality that the fins of a sea beast have, but as we dreamers better understand how such fin features as bouyancy, flexibility, recoil speed, outline – those of fin placement, cambering, cant, and toe in differential – can read how cord length, thickness and arrangement change effect – better marry many complex curves in a similar way to those of the divine creation – how to best apply the vast quantity of composite options available to these fins we fashion they will better serve the performance curve recquired by a surfer, his particular board and the surf conditions he finds himself in. A we will live the dream.
Gotta fix a few dings, Rich