Rail fins: Better to measure from rail or from center?

YOUR WRONG THERE,

WATCH SOME UNDERWATER SHOTS OF A BOARD.

THE FINS ARE IN THE WATER 95% OF THE TIME ,AND THE BOARD IN GENERAL, IS RIDDEN FLAT,EVEN WHEN GOING UP AND DOWN THE FACE( IN AN EXTREME TUBE RIDE AT PIPE ON A THRUSTER, ALLTHE  FINS AND THE LAST TWO OR THREE FEET OF BOARD IS FLAT TO THE RIDER AND IN THE WATER…A BAD TIME FOR MISALIGNMENT,BRA !).

…THE ONLY TIME THAT THIS IS NOT THE CASE IS ON HARD TURNS,WHEN YOU REALLY NEED THE BOARD TO RESPOND CORRECTLY////////IN AND OUT OF THE TURN.

A BOARD THAT DOESN’T TRACK CORRECTLY WILL… DIE, DO WOOPDIES,SPINOUT… IN CUTBACKS OR HARD TURNS… MAKING IT INCONSISTANT.

IT’S YOUR CHOICE…I BUILD MY BOARDS TO SUIT ME FIRST AND THIS IS WHAT I’VE FOUND TO BE THE TRUTH.

HERB

Good point Herb -

I’ve spent lots of time looking at photos for these reasons, so thanks for reminding me.  I would, however, suggest that there is a definite difference in the pressure being applied to one side of the board over the other, but I’m not sure that discounts your position. 

That being said, I’ve not experienced any problems having my fins set asymmetrically, but I’d love to hear about others experiences comparing the ride/feeling of standard tri set up v. asym set up…

Granted, we’d have to get into things like the board needing to be the same, which I do have the ability to test - one board, movable side fins - and I have not noticed a difference in the pocket, I’ve noticed slight difference in the initiation of turns/rail engagement.  Of course this could be because it was suggested to me by Tom@Duam, and I just think I feel it.

Let my ask you this Herb  - If I agree with you about the function and performance, then why/how/what is it about the fins being symmetrical from the center line which causes them to have an increase/decrease in their function.

And, lastly, what is “dragon skin?”  I’m with you on the use of nice heavy duty sanding devices.  Makes me wish I’d saved some of my old flat skate deck w/“pizza” grip…

 

Thanks for working w/me -

Off the rail.

The rail determines how you can set the AOA of the fins.

The wave doesn’t care and doesn’t know where the center line is, it does, though, know (to anthropomorphize the wave) where the fins and the rail is, and the fins and the rail are what the board is interacting with.

For the most part, the outside fin is not important, until it becomes the inside fin (like during a cutback).

Taylor,

Dragon skin is typically used in drywall/carpentry applications.

May typically be a sheet of flexible plyable steel sheet   4" wide by 15" long, the steel is perforated with holes

etc. to give it a very grit abrasive surface. Somewhat held like a shoeboys polish rag with both hands.

The stuff gained some notoriety through John Carpers Shaping 101 video/cd

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Hey Herb is this the Dragon Skin Handle your talking about:

http://doitbest.com/Sandpaper+holders-Red+Devil-model-3329-doitbest-sku-336540.dib

 

I’ll work understanding the other 2 refs later.

Your help and ideas are appreciated.

That dragon skin holder is brilliant… I really HATE the surform. Can’t tell you how many times I’ve rolled it over and put a huge gouge in the nose rail.

toe-in and camber…why?..where’d it come from?

automotive industry…where else.

yes,otis,

the red devil holder…it works killer ,so do the others mentioned.

as far as setting fins from the rail or center…it’s your choice.

the waves don’t think…you’re correct on that one ob…but do you?

of course you do…i played alot with asymetrics back in the 70s and 80s…and by my experience… an even setting on mulitfinned boards works better…period(provided the shaper is skilled enough to shape a clean board…and the glasser,if you use one,doesn’t f#%k it up).

if your shape is clean… then it really doesn’t matter where you measure from,and you should measure from both to mike it down anyway.

the real; joke here… is… you really set from both center and rails at all times,whether you are consicence of it or not.lol.

herb

Right on Herb -**“if it works for you,whatever it is,and makes you feel good about your accomplishments…do it!” **Heck - This is the frame I make my boards on.  I try to use a foundation of basic hydrodynamic principles, and go from there, but there are times when my attempts a melding some ideas doesnt’ work out so well.

I’m not trying to be dick for the fun of it, heck, I’m not trying to be one at all (Hope I’m not too much… Ha!)

I think one reason I like to “push” the issue is, in your what I quoted from you above - “If it works.”  It seems sometimes folks here are suggesting if the fin(s) are off by much, as little as less than 1/2", then the board won’t work.  My experience, and that of my test rider, a former traveling pro, is symmetry, at lest when it comes to tail out-line, foil, and fin placement, is not the primary concern.

“The outside fin does more than just sit the wait for
redirection…it’s the whole purpose for the vacuum lift
and stick.”

Herb - or anyone else - care to elaborate on this…  This is what I was referring to when I said I’d been studying photo’s and videos for insight into pocket/tube riding.  And, given the nature of the way this thread is going, and the thread I’m about to start, I’d like to see what people think about lift, speed, control, etc…

As for the Dragon skin… Looks awesome - I’l have to find some before I start the next board.

 

Dragon Skin:

I tried looking at various hardware stores…burnt up too much time and gas.

FoamEZ: http://www.foamez.com/dragon-skin-p-176.html

 

although the picture doesnt do it justice, typically you wrap each end in duct tape as handles.

Right on… Does it flex?  'Cuz, from people have written, it sounds like it does.

i don’t use the dragonskin by it self.just never saw the need/PRECENTAGES.

but in the holder that red devil makes ,it turns a so-so tool into a mean motorscooter !

as far as the vacuum goes…it IS the basic principal of,“why you toe and cant fins”.

YES,TOE AND CANT HELP RE-DIRECT THE BOARD IN TURNING,BUT IT’S THE VACUUM THAT THE RIDER BEFEFITS FROM THE MOST.

THE VACUUM CREATED FROM THE TOEIN/CAMBER HELP PROPEL AND STABLIZE THE BOARD.IT’S LESS LIKELY TO TRACK,SLIP-OUT,OR BOG THRU MANEUVERS.

ESPECIALLY IN FASTER WAVES.

THE VACUUM CREATES LIFT WHICH TRANSLATES INTO MORE FORWARD MOTION,AND GREATER STICK.

EXCUSE ME MY KEYBOARD GHOST IS ACTING UP AGAIN !

HERB

Thanks for sharing your knowledge and experience.  I can see the reasoning in both your and TaylorO's logic, but what do you do when the stringer isn't straight.  I'm sure you've dealt with a ton of crooked stringers.  If the entire stringer is bowed from tip to tail do you straight edge the stringer before you cut the outline and after you shape to set the fins?

return it for an exchange.

if this is not possible ,then yes you either re-draw the centerline and ignore the stringer or cut it out and replace it.

herb

I’m with you on lift Herb - But I’ve understood that toe-in had to do with helping in turn initiation and tracking reduction - but toe-in supposedly increases drag while going straight.

As for the car analogy - what about the fact a car, for all intents and purposes, has the same power going right/left - “front/toe side”/“back/heel side?” 

My point is this:  I’ve used asymmetry do to the fact I do not apply the same power with my toes and I do with my heels. I know this is one of the areas I feel my body is “sensitive,” i.e., I’ve really noticed the difference over the years.

Do you, or anyone, take this into account?

toein does help in turning,yes…it also helps in creating a vortex = lift and stick.

the human factor is the most important factor.

you ever see someone ripping on a board ,that was unknown to you in design,you get a chance to ride it in good surf and it does everything wrong for you… less killing you on the spot.

the human factor.

i think builders and riders have lost sight of the reasons ,why we have side fins at all,maybe because …it time to lose them…for awhile…anyway.

i got a completely new design ,fin and tail coming aboard .it should be done by this week.

it involves several theories,and countless hours of wind/tank/computer time involved.

it will be easy to shape/duplicate…and parts are readily available/already exsist.

I call it ,“spitzer boattail bullet”.

a big thankyou to bill thrailkill for the help/knowledge/and his design theories,and a big thankyou to tomatdaum for his help/knowledge/and his design theories.

w/o bill t.and/or tom o’keef this design,may never have been built.

once it’s in the water…it should prove to be superior to anything past or present,in any conditions…period.

herb

Well Herb…  Those are some mighty big claims…  Defiantly looking forward to seeing pictures.  

heck, it may end up being a dog !

 most of the people that saw my first quads back in the 70s said, the design would never work,that it was a gimmick…oooppss!!!

i have a positive attitude,and everything so far has just fell together like having the right key for the right lock…

 

…i can not only hear ,but see the tumblers falling into place…right before my eyes.

…like i’ve done this before.

probably what a true revelation must feel like…trippy.

just finished shaping the blank and it’s killer…i’ll have to fine someone to post pics of them for me.

nice swapping spit with you taylor,you too think.

a year ago i was as far away from surfing as a person could be…like i never even seen the ocean before.

today,i feel close…real close.

mom,i’m home!!!

herb

Right on Herb… Feeling a stoke shiver just reading your stoke on it…

For all the best and the good…

Waiting for pics…

yeaah,

can you see it…the future belongs to those who see it coming.

thanks taylor.

it’s going to turn heads…that’s foresure !

heading out to paint it right now !

herb

paint’s done,looks like fire and smoke in the air.

herb