Fin theory,tom,halycon and others

General Discussion
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I’ve lost (for now at least) TC’s email and snail mail addresses and I dont recall ever seeing any pictures to support the words. So for my part I’m just going to drop that one.

That said I still consider humans and their inventions part of the evolution on our planet. Why should what I say matter anyway? And who am I? NO one really. However, who can deny the existence of or that all this man made stuff everywhere is surely evolutionary. But like George Carlin said in one of his humor skits; Earth created humans because it wanted plastic. And when it’s got it’s fill of plastic it will shake humans off like a bad case of fleas.

I suppose that’s probably a more realistic scenario than we would like to believe.

Anyway, thanks for the encouraging words. It’s no secret that I get many of my ideas for surfboard fins from observing nature or human nauture (the Mulhern pump was part of my thoughts regarding how MVGs might help; did it mimic the swishing tail of the tuna?). So At least that is my kick off point. NO good idea stands alone. And I always try to give nature her due.

However, I am dumb. Still can’t find my notebooks. All this paper information I’ve been accumulating has become the biggest problem regarding finding stuff here. When I started I had one desk, now I have five. And they are all just for me. Not to mention overflowing file cabinets and bookcases. And boxes of more books. That plus getting ready for a FL run tomorrow night and my shoulder killing me with nerve damage. I’m just about out of stoke for looking. I’ll give it attention when I get back next week.

As for the bumpy trailing edge that is as I see it a step in the trial and error process formula. Not to be discounted but not the be all to end all either.

We’ve only begun to scratch the surface. With almost 9K views of this thread someone is watching. Permutation computations predict a billion billion monkeys continuously hammering away at typewriters will eventually produce the complete works of Shakespere. Or did I just make that up? i seem to remember someone saying something like that years ago. Sounds good though (grin). Anyway, fins have room to get better.

We just need a few bizillion more monkeys.

I talk this way because this is how I think and that is how I put seemingly odd ideas together. Besides I dont want to spoil anyone elses fun with promoting my ideas over anyone elses. That would also mean I would be telling what I’m making. Cant do that because I’m still thinking.

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My theory on Humpback bumps and tubercles. They have nothing to do with hyrodyanamics, in fact are probably an obstacle to it,the opposite sex finds them attractive. “The nicer the bumps, da more ya get to Hump!” Mike

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Ironically I believe I read that that was one of the thoughts prior to the hydrodynamic theory.

Back when many evolutionary changes were thought mainly to be to attract the opposite sex.

Not far off still. Better surfers get more chicks. Right?

How about this. Maybe the tubercles help the male humpback ride female humpback and vice versa by giving better perhaps interlocking grip. Maybe that’s why they need such long bumpy front fins? Maybe they do both or even more?

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I like your better grip theory, too, Mark. There are many examples of adaptations that attract mates that have no other obvious function. Some provide fewer advantages to the individual, but benefit the profundidity of the population. Example, the brightly colored feathers of the peacock certainly do not help it blend with the evnvironment to escape predators. The peahens DIG IT, though. Called sexual selection. My favorites example. Women’s boobs. Little ones do not make more or better milk than big ones. Why have big ones? Mike

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More whale craziness:

So the whales seems to play with the different realms they live in. Descriptions of close to surface upside-down swimming “at speed” with fins curved and half out of water. An ancient instinct for airborne flight? Looking at the sky from beneath the water. Even whales experiment.

Take away: curved fins… (Roy; Greg Webber, you out there?)

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Fine examples. Now you got everyone’s attention. I knew one female golf pro who had to have two reductions just to get her swing around or to see her ball. No joke. She was that serious. So big ones certainly are not a benefit in playing golf.

However:

My thought was anyone that would take man’s toys away was not a good candidate for reproduction or marriage. Last I heard she was still single so I guess I wasnt the only one who thought that. This is not about sexism, but about sexy. There is less motivation to perpetuate the species without sexy; or alcohol.

But we are getting far afield.

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Interesting thoughts there Rob. Whales are amazingly great aerialists. Imagine what it would feel like if we weighed 20 tons and could leap 50’ vert and hit the water.

Why do they do that?

From my readings no one knows for sure. Some scientists speculate that it must be painful for them due to their great size and the height of their airs. This only raises more questions.

I’d like to see Taj go 50’ vert! Bet that landing would hurt.

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Hi Guys

just a link to an interesting foil page ,note the disscussion on thickness, leading edge radius and max camber position

Mike

www.vacantisw.com/foildesign.htm

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Yet another interesting foil

www.foils.org/hysecdes.pdf

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sabs,

I am unclear on the process by which I might take one of these foils and apply it to a fin I am making.

I guess, if I were making a mold, it could all be programmed in and precise.

However, in making fins my hand, it seems to me to be exceedingly hard to make a foil match anything with enough precision to make a difference. I am not saying you cannot put the wide point as far forward or back as you like, or round the front edge appropriately, or roughly approximate a foil curve.

But getting it really close would be really tough with the tools I use. Do you have any suggestions?

I ask because posting of specific foils suggests implentation, and I feel there are very few here indeed capable of appropriately taking a foil from cross-section to fin.

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Hi Blakestah

Thanks for the responce,as you may have guessed the second link with the foils just had me interested in foils for thruster side fins

I make up my own solid stock carbon and glass epoxy, then use the large belt sanders at work,these are large machines with 8 " wide and 3’ long sand ing areas we also have spindles ranging from 1/2"through to 8"

all i do is drawup the fin with sections then take templates and start shaping

I guess with these machines its cheating cause if I just had the grinder it would be way harder

The first link may have been of some interest to the single fin people as the importance of leading edges is discussed

I will try to shape up some of the side fins as soon as I built up some more solid stock

They might be interesting with your plan shapes

I will let you know how they go

At the moment the cutaways I posted earlier are rapidly becoming my most liked

The other weekend I tried them and my much loved sloted biplane ones

I was supprized at how much better the cutaways felt compared to my previously considared perfect fins

I guess change is allways good when it works

regards Mike

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well , things have certainly been moving along without me …

some impressive concepts have been put up , its taken me hours to catch up ,plus check the various links …

sabs i was absolutly stoked to read that link on foils …it completly confirmed what ive concluded after years of fin experimentation…

the pics ive stuck in are of the best fins ive ever used to date ,confirmed not only by myself but also my team surfers and the many results theyve achieved over the years with these fins,

they have a base chord of 105mm and a base camber of 14mm thus putting them in the desired 13 - 15 % range for maximum thickness to chord ratio…

i found it interesting that trial and error and some intuitive intelligence would actually come up with the same results as NACA with there multi million dollar budget…

it kinda feels like im a little fish swimming against the tide of popular opinion,when along comes a big fish swimming in the same direction that i can swim along side…

theres alot of other comments i want to reply to but ill save it for another time …

whether the ultimate fin has been found or not , who knows?

but its really kool to see logical progression , at the end of it all ,we all stand to benefit in our overall understanding of the functional range of fin performance…

tom ! i was impressed with your appraisal of halycons fins…

tubedog ! same with your comments …i was impressed with your ability to put into words exactly what you felt ,i agreed with everything you wrote…

first day back so i had to do alot of reading and not much writing…when im on next i wanted to reply to daddio and also halycons questions on another thread…

till next time

regards

BERT

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Bert

good to have you back

lets hope that we can keep this and the washout thread going in the right direction

As i a past post of mine section shapes with one of those pin things would help fill in the pic a bit more

Check the new FCS site I have only watched the film as there is no sound on works computer I will try at home to see if what they say makes sense

Hope reason stays here on line

Mike

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And what, exactly, is the ‘right’ direction?

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Roy

A direction which has benefits us all in building and using surfing equipment and does not degenerate in to a discussion on individuals character.

I sense that you have got a bit of a problem with my comment

I would once again refer you back to a comment I made before, where I said that may be we should be more focused on a target size or usage range for our disscussions

As Bert started this highly informative thread may be it should be his preference as to what this target size and range is.

The same criteria should apply to the other washout fin thread of halcyons

And of course this would also apply to any thread that you care to start

Any moderaters have a comment?

I just like to chew the bacon not sling the mud

Mike

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Mate,

If you want to start a surfboard size specific thread, then go for it.

My comments regarding fins have not been surfboard size specific. Furthermore, who are you to decide that only certain kinds of fin theory are useful to everyone? And why does a post have to please everyone to be valuable?

Are you really suggesting that there is a ‘kosher’ board length for the purposes of fin discussion?

R.S.

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Damn Roy,

 An antagonistic point is good occassionally to stimulate discussion. But, you poison each design thread that you contribute to with your persistance. How about starting a thread of your own!
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Roy

Really I will not stoop to this level of cynicism and ruin this good thread

READ MY POST AGAIN i never suggested that I should decide what is usefull to every one

Kosher ! its a fin disscussion, what can be done on a ten foot board requires differing fins and setup to what is needed on a six foot board which is used for smaking the lip repeatedly

Before you jump to another conclusion Roy I ride both a six foot and a ten foot six board to me they are worlds apart,both are equally fun

Thats the end of my comments on this rubbish

If you want to go further with this disscussion post your phone number in a private message and we can discuss it after all we are in the same country

Mike

ps please note the name its not mate

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Kindly cease to blaspheme in your communications with me. Persistence is a quality, not a poison. I would like to discuss hydrodynamics and I am reminding you that the present level of discussion was started by Mr Burger’s obscene statement regarding myself. R.S.

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No problem Mike, I am happy to discuss fins for boards of any length. Roy