Author Topic: Board flex / tuning fork  (Read 3011 times)

SupTrip

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Board flex / tuning fork
« on: August 24, 2014, 09:29:38 PM »
I've been wondering if anybody here can offer some input or opinions on the effect of board "flex" has on the performance of a racing sup. Is it beneficial / detrimental? Why?

Personally I don't think manufacturers intentionally engineered the flex into the boards. I think they noticed it, and then creatively labeled it and touted its benefits.

Im sure if there is a effect on performance, its minimal, but races are lost by small differences in time right?

All my experience with this stems from my 2014 allstar i reconstructed, and my unmodified 2014 allstar and 2014 sprint. If i pick up the tail of my sprint and raise it 2' off the water, then drop it, it reverberates significantly.

My reconstructed allstar does not do this, and feels generally stiffer. Obviously this is the result of the large sections of overlapping layers of carbon fiber added during repairs.

Instincts tell me, board flex could be a parasitic loss of the energy from my stroke, i.e. anything happening other than forward movement is a waste. 

So whats the general consensus? Any sound reasoning behind it?

pdxmike

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Re: Board flex / tuning fork
« Reply #1 on: August 24, 2014, 09:43:45 PM »
It seems like all flex would be bad.  Nobody lets air out of inflatables to speed up.  My Javelin is my fastest board, and I'm sure part of the reason why is it feels like it has no flex at all.  The 14' Surftech Bark Dominators of 3 or 4 years ago were known for being very flexy, and lots of people moved onto other race boards because of that (part durability issues, but also part performance).

DavidJohn

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Re: Board flex / tuning fork
« Reply #2 on: August 24, 2014, 11:08:34 PM »
Personally I like no or very little flex.. I'd rather a heavy board that's stiff rather than a super light board that flexes all over the place and does the boing-boing thing when you paddle over a boat wake..  :)

karl

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Re: Board flex / tuning fork
« Reply #3 on: August 25, 2014, 12:10:38 AM »
There's a very in-depth discussion of resonant frequency over on Swaylocks and how it influences surfboard performance, including how to measure it.

I can recall a soft epoxy 12' SUP resonating while paddling at certain speeds over small chop. i felt that was bleeding off paddle power.

But it makes you wonder if you can match a paddle stroke with resonant frequency of a race SUP to enhance overall performance.

Anyway, it will make your head hurt!

http://www.swaylocks.com/forums/hard-numbers-flex-demystify-flex-patterns

SupTrip

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Re: Board flex / tuning fork
« Reply #4 on: August 25, 2014, 06:58:45 AM »
Really good point about the inflatables.

I think the swaylocks info is very cool, but i can see where flex would give those guys more ability to hold a line in a turn etc. like suspension in a car.

As far as matching resonant frequency with stroke etc., im not Wile E. Coyote - super genius- but wouldn't the best possible result of this harmonic matching up be the recovery of energy put into it making it? Better to never lose it at all than worry about my riddims.

I like the stiff board too, the reconstructed allstar is heavier but solid, its the lead sled.

baddog

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Re: Board flex / tuning fork
« Reply #5 on: August 25, 2014, 11:36:48 AM »
For actually surfing equipment, we know snappy flex is crucial.  I'm undecided on racing SUPs, but I'm leaning towards a bit of flex for a couple of reasons.  Just like in making a surfing turn, a racing stroke might benefit from a bit of 'pop' from the board.  Also a bit a flex will dampen shock in rough conditions.  I also believe you cannot make a long race board super stiff without it being super heavy or super expensive.

Here's what Scotty from Starboard said regarding our 2014 All Stars when I asked about features and construction.  "TSar flex carbon= 100 grams biaxial carbon. Is the angle of the weave of the carbon which makes a massive difference regarding flexibility, which equals life in a board. controlled flex and recoil of the board (developed by Starboard)".

JimK

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Re: Board flex / tuning fork
« Reply #6 on: August 25, 2014, 12:44:26 PM »
Stiffness is critical in race boards PARTICULARLY to us Big guys. It is alot of the reason boards don't perform for big guys like it does for others. There is no STANDARD I've found to discribe flex in a board like we have in say windsurfing masts
I doubt there ever will be
but my 2cents (non scientific) I love Fanatics stiffness to me (accross the whole line) is stiffer than other (production) boards but again it is what I FEEL when I put my 300# 's on it

Let's not start another S__T fest like the last post I responded to

JimK

SupTrip

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Re: Board flex / tuning fork
« Reply #7 on: August 27, 2014, 10:02:24 PM »
Can one of you guys tell me if my 2012 brushed carbon coastrunner is the same pvc sandwich construction as the newer carbon boards from starboard? Or is it just glass/carbon over eps?

I think the pvc sandwich is a good idea, but i wonder, isnt just plain glass over an eps core a sandwich of sorts? I mean, if the the board is stressed to deflection at the standing area wouldnt the the topside of the board be in compression and the bottom in tension? Isn't that the intent of the sandwich structure?

My coast runner is stiffer than my new boards, and the carbon fiber looks like that traditional heavy bi weave stuff, vs the paper thin 2k ultra stuff.  It also seems lighter than my new carbon boards. I dont know much about composite design, im just making assumptions from what ive observed.

cnski

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Re: Board flex / tuning fork
« Reply #8 on: August 27, 2014, 10:52:01 PM »
Yes, plain glass over an EPS core is a sandwich by a composites definition. But usually when you hear "sandwich" in regards to a SUP, or more commonly a sailboard it refers to EPS, PVC, and glass. Not sure about your coastrunner, however.

 


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