Author Topic: Scientific Flatwater Board Testing 101  (Read 27460 times)

ukgm

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Re: Scientific Flatwater Board Testing 101
« Reply #90 on: June 28, 2016, 11:49:53 PM »
https://en.wikipedia.org/wiki/Planing_(boat)

I found this explanation on Wikipedia:

How planing works:
When it is at rest, a vessel's weight is borne entirely by the buoyant force. At low speeds every hull acts as a displacement hull, meaning that the buoyant force is mainly responsible for supporting the craft. As speed increases, hydrodynamic lift increases as well. In contrast, the buoyant force decreases as the hull lifts out of the water, decreasing the displaced volume. At some speed, lift becomes the predominant upward force on the hull and the vessel is planing.

Everyone knows wikipedia is gospel ;-).

Can we move on and maybe even get back on thread ? (start a new one for the planing argument)

blueplanetsurf

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Re: Scientific Flatwater Board Testing 101
« Reply #91 on: June 29, 2016, 12:08:53 AM »
Yes, you can feel it.  To me, Travis surfing on the big wave is clearly planing, no doubt about that.
But going back to this photo of riding a bump at lower speeds (less than 12 mph), I would still call this planing.

You can see the rails of the board are not touching the water, the water is spraying off the tucked under rail and not wrapping around the rails.   The paddler's weight is therefore clearly supported predominantly by the lift created by water moving under the bottom surface of the board, not by the buoyant force of the rails.  If you look carefully you can see that the rails are not really touching the water, so the lift created by the board's volume is minimal in comparison to the hydrostatic lift.

So to me there is are only these two states:
1) Displacement where the predominant lift comes from the displaced volume
2) Planing, where the predominant lift comes from hydrodynamic lift. 

The transition between these two states is very noticeable, either fast acceleration and a sensation of lifting and sliding on top of the water or deceleration and a feeling of the hull dropping back down into the water.
« Last Edit: June 29, 2016, 12:35:11 AM by blueplanetsurf »
Robert Stehlik
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blueplanetsurf

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Re: Scientific Flatwater Board Testing 101
« Reply #92 on: June 29, 2016, 12:10:26 AM »

[/quote]

Everyone knows wikipedia is gospel ;-).

Can we move on and maybe even get back on thread ? (start a new one for the planing argument)
[/quote]

Ok, sorry, I'm done
Robert Stehlik
Blue Planet Surf Shop, Honolulu
Hawaii's SUP HQ
http://www.blueplanetsurf.com

yugi

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Re: Scientific Flatwater Board Testing 101
« Reply #93 on: June 29, 2016, 01:02:44 AM »
Back to Scientific Flatwater Board Testing 101...

Is it true red boards are faster?

mrbig

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Re: Scientific Flatwater Board Testing 101
« Reply #94 on: June 29, 2016, 05:02:14 AM »
Only in pantone 805 c 2x!!
Let it come to you..
SMIK 9'2" Hipster Mini Mal
SMIK 8'8" Short Mac Freo Rainbow Bridge
SMIK 8'4" Hipster Twin
King's 8'2" Accelerator SharkBoy

Bean

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Re: Scientific Flatwater Board Testing 101
« Reply #95 on: June 29, 2016, 06:28:35 AM »
My red (Pantone 186C) 14x28 Fanatic was faster on flat water than my yellow and black 14x26 Javelin.  ;D

ukgm

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Re: Scientific Flatwater Board Testing 101
« Reply #96 on: June 29, 2016, 06:59:21 AM »
My red (Pantone 186C) 14x28 Fanatic was faster on flat water than my yellow and black 14x26 Javelin.  ;D

What year models ?

LaPerouseBay

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Re: Scientific Flatwater Board Testing 101
« Reply #97 on: June 29, 2016, 10:22:28 AM »

How ironic.  The master of spin wants lab results.   


I've been clean for ten years.

Perfect analogy, once an addict, always an addict.

/
Look at windsurfing board from the 80's, look at a modern one. We had a hell of a time getting older windfurers to plane. Why? Because they didn't have a planing hull. Talk to any shaper that did both windsurfers and surfboards. Tell him that you think your 14' rockerd board is planing. If he doesn't laugh at you it wil be because he's nicer than me.
/

http://www.standupzone.com/forum/index.php/topic,10934.msg96137.html#msg96137

Hey, this spin stuff is kinda fun! 
Support your local shaper

Bean

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Re: Scientific Flatwater Board Testing 101
« Reply #98 on: June 29, 2016, 10:37:39 AM »
My red (Pantone 186C) 14x28 Fanatic was faster on flat water than my yellow and black 14x26 Javelin.  ;D

What year models ?

2011 Fly Race and 2015 Javelin LE.  But, the Jav is a better all-rounder for sure.

mrbig

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Re: Scientific Flatwater Board Testing 101
« Reply #99 on: June 29, 2016, 02:00:42 PM »
Bean, those are the paint codes for my JP 2015 race. Fast, but really tippy. Changed in 2016 again and in 2017..
Let it come to you..
SMIK 9'2" Hipster Mini Mal
SMIK 8'8" Short Mac Freo Rainbow Bridge
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King's 8'2" Accelerator SharkBoy

Bean

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Re: Scientific Flatwater Board Testing 101
« Reply #100 on: June 29, 2016, 02:12:40 PM »
186C is really the code for the more recent Falcon, so I was just winging it. ;D


PonoBill

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Re: Scientific Flatwater Board Testing 101
« Reply #101 on: June 29, 2016, 03:02:19 PM »

Perfect analogy, once an addict, always an addict.
Yeah, well, maybe.

But ask Bill if he thinks his Maliko 14's actually plane.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

ukgm

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Re: Scientific Flatwater Board Testing 101
« Reply #102 on: June 30, 2016, 12:07:19 AM »
https://en.wikipedia.org/wiki/Planing_(boat)

I found this explanation on Wikipedia:

How planing works:
When it is at rest, a vessel's weight is borne entirely by the buoyant force. At low speeds every hull acts as a displacement hull, meaning that the buoyant force is mainly responsible for supporting the craft. As speed increases, hydrodynamic lift increases as well. In contrast, the buoyant force decreases as the hull lifts out of the water, decreasing the displaced volume. At some speed, lift becomes the predominant upward force on the hull and the vessel is planing.

Everyone knows wikipedia is gospel ;-).

Can we move on and maybe even get back on thread ? (start a new one for the planing argument)

Larry has now put his own data up here: http://www.larrycain.ca/blog/blog/

I'm going to add some stats to his FB page regarding it later in the day.

Pierre

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Re: Scientific Flatwater Board Testing 101
« Reply #103 on: June 30, 2016, 03:46:44 AM »

(Note: I'm a little sceptical of manufacturers claiming they can promote or optimise dynamic aspects such as board flex - partly since this is incredibly difficult to simulate and robustly prove and requires some degree of scientific ability that most manufacturers either don't have or just haven't invested in the resources yet - especially the smaller ones. Team athletes offer the most qualitative feedback but don't generally have the ability or the time to provide robust quantitative feedback). I guess this leaves us with what you are saying (in that elite athletes and medium level  paddlers probably should not use the same boards) but either way, we should be looking at test methods beyond just the subjective when it comes to flatwater racing.)
this is experience- based, how can we explain an inflatable works so good in some conditions, with its negative middle rocker in still situation?  something like a surf mattress surfing?...  flex stores energy and gives it back,  the most difficult is to direct this back energy the right way....
I have some plywood hollow SUP boards with minimal structure ( longitudinal only), keel is quite still but bottom sheet a bit flexible, and despite their weight, they perform unreally well.... :)
\HF/- Hi-Fun Hydroworks / custom boards,BZH, since 1982  /  *Link Removed*

ukgm

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Re: Scientific Flatwater Board Testing 101
« Reply #104 on: June 30, 2016, 04:33:06 AM »

(Note: I'm a little sceptical of manufacturers claiming they can promote or optimise dynamic aspects such as board flex - partly since this is incredibly difficult to simulate and robustly prove and requires some degree of scientific ability that most manufacturers either don't have or just haven't invested in the resources yet - especially the smaller ones. Team athletes offer the most qualitative feedback but don't generally have the ability or the time to provide robust quantitative feedback). I guess this leaves us with what you are saying (in that elite athletes and medium level  paddlers probably should not use the same boards) but either way, we should be looking at test methods beyond just the subjective when it comes to flatwater racing.)
this is experience- based, how can we explain an inflatable works so good in some conditions, with its negative middle rocker in still situation?  something like a surf mattress surfing?...  flex stores energy and gives it back,  the most difficult is to direct this back energy the right way....
I have some plywood hollow SUP boards with minimal structure ( longitudinal only), keel is quite still but bottom sheet a bit flexible, and despite their weight, they perform unreally well.... :)

If you're going to promote board flex as a performance enhancing effect (as Starboard do), you can't just use anecdotal experience for the reasons I've given. The magnitude, direction and timing of the energy return is critical (I've been involved with this problem with respect to prosthetic limbs used for running). As always, some boards might do well 'in spite of flex' not 'because of'. We need data for that.

 


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