Author Topic: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard  (Read 13697 times)

Larry Allison

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I know you have been asking this question for awhile: Why 4 Fins over Single Fin on a Race Board. Thanks to a Paddler in New York, John Judge took the time to do a in depth break down. Enjoy my friends. Mahalo,Larry

https://www.youtube.com/watch?v=4ysPPYOcXw8
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Night Wing

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Although I don't do any sup racing, I enjoyed watching this video. I really like all the detailed information John Judge provided plus his commentary.

Thanks for sharing it.
Blue Planet Duke: 10'5" x 32" x 4.5" @ 190 Liters (2 Dukes)
Sup Sports Hammer: 8'11" x 31" x 4" @ 140 Liters
SUP Sports One World: 11'1" x 30" x 4.5" @ 173 Liters
CJ Nelson Parallax: 9'3" x 23 1/2" x 3 3/16" @ 78.8 Liters (prone surfing longboard; Thunderbolt Technologies build in Red construction)

burchas

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I have the same fin setup as John Judge on my SIC FX 12'6 and I'll second his findings.
Aside from the top speed test which I haven't gotten around to yet, I share all the other
conclusions:

  • Improved stability
  • Better tracking
  • Improved handling in chop and confused water
  • Improved foot steering control

I should have more flat water speed results this week
in progress...

krash

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Thanks for sharing, I read a lot on fins and first time seeing a fin forward like that, may solve some of my issues will look more into those.
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BroDog

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Great review John Judge!!!  I've been riding on the 4 fin system for the past 3+ years.  I agree with everything already mentioned.  The system offers amazing versatility in fine tuning your sup board to various water conditions. Speed, stability, projection, tracking are superior to a single fin.  In addition, the probox system offers innovations in fin technology that Larry Allison is continually pumping out of his lab.

ukgm

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I really enjoyed this video. Having done a fair bit of equipment testing now myself, I was pleased to see someone else doing a decent number of runs and being pretty organised about what they are doing. I would like to have seen the raw data and stats of the runs themselves (and worked them through) but then I'm a nerd for that sort of thing.

The only criticism I would have is I would not rely exclusively on sprint efforts as I think that is not representative of racing and steady state sustainable efforts typically generates better quality test data  (and is more representative of races if the right velocity is selected)

Bean

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What exactly is fin "projection" in straight-line flat water paddling?

Here is why I ask.  I've always undestood "projection" to be the energy that's released by a fin, usually under a heavy turn.  For instance in surfing, a flexible single fin will give you more projection off a bottom turn than a small quad set up.  The flexible single fin loads up in the turn and releases that energy as the rider changes direction creating what surfers call "projection".  There is a cost to projection, in a heavy turn you put more energy into the fin than you get out of it, but who cares, in this case the energy is coming from the wave.

Clearly it's different in flatwater paddling.  Are you saying that when we paddle, we load up our fin(s) on every stroke and they release, providing "projection"?

PonoBill

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Good stuff. I don't know what projection is. Perhaps resistance to torque? I'd like to see longer distances as well. There's not much question that multiple fins add drag, that's just physics, my question would be how much the increased tracking and stability lets the paddler overcome the drag with more efficient stroking. The equation might shift the other way with greater distance.
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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Clearly it's different in flatwater paddling.  Are you saying that when we paddle, we load up our fin(s) on every stroke and they release, providing "projection"?

I thought that was 'drive' ?

supuk

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i think the results would me a lot more if there was a third test with the single rear and the ventral fin, you wouldn't test a sail boat without a daggerboard and expect to get the same performance.

Bean

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #10 on: August 16, 2016, 10:41:09 AM »

Clearly it's different in flatwater paddling.  Are you saying that when we paddle, we load up our fin(s) on every stroke and they release, providing "projection"?

I thought that was 'drive' ?

Projection and drive are a little different.  For instance, on a bottom  turn you will experience drive as you push off on a stiff pivot style fin.  (You need drive to maintain direction but the cost is increased drag.)  Moving to a more flexible fin, you'll get a little less drive and maybe a little less drag but you will get more projection as the fin releases (or springs back). 

But again that's surfing, and the wave is doing all the hard work.  What I'm interested in here, is understanding how "projection" translates to a flat water board.  BTW, I don't think it does, but would love to be wrong about that.

Larry Allison

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #11 on: August 16, 2016, 11:40:08 AM »

Clearly it's different in flatwater paddling.  Are you saying that when we paddle, we load up our fin(s) on every stroke and they release, providing "projection"?

I thought that was 'drive' ?

Projection and drive are a little different.  For instance, on a bottom  turn you will experience drive as you push off on a stiff pivot style fin.  (You need drive to maintain direction but the cost is increased drag.)  Moving to a more flexible fin, you'll get a little less drive and maybe a little less drag but you will get more projection as the fin releases (or springs back). 

But again that's surfing, and the wave is doing all the hard work.  What I'm interested in here, is understanding how "projection" translates to a flat water board.  BTW, I don't think it does, but would love to be wrong about that.

Looking at the simple diagram, 1.)Paddle stroke pulls the board forward and Torques the nose of the board. By adding the Ventral fin here. It counter acts the pull of the nose right to left which is greater on a heavier, taller, stronger paddler. This aids in Projection. 2.) Lateral drift left to right at the tail then is stopped by the center fin which depending on structure built of the center fin will give lateral resists for the board to push off of creating forward movement 3.)Projection 4.) the flex twist off the tip of the Sup fin is release which reacts different then loading up the fin in a bottom turn of a surfboard that snaps back after coming out of the turn which then has power by the wave from behind. Unlike a Sup fin which is always carrying lateral load in a flatwater situation. Again my friends a Surfboard World is not a Sup World. Thanks for sharing your thoughts.
« Last Edit: August 16, 2016, 11:42:01 AM by ProBox-Larry »
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Larry Allison

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #12 on: August 16, 2016, 01:51:30 PM »
Here is a cart from Blkbox Rider Maggie Adams with a breakdown of fin combinations in same board:

Tests Performed by Blkbox Rider Maggie Adams
Table 1
Fins                                            Time (min)    Miles   MPH     SPM    D/ST
Twin Box/Ventral/kicker                 6.24           0.43     3.96    48         8.2ft
Twin Box/No Ventral/kicker            7.21           0.43     3.49    47         7.5ft
Single Fin Blk Box Fiberglass          6.24           0.43     3.96    48         8.25ft
Single Fin Kicker                           5.49           0.4       4.12    47         8.4ft

Conditions: Heading W-Head on wind & chop, & some boat wake, E-down wind
SPM= stroke per minute
D/ST= Distance/stroke


Twin Fins: 4" by 9" Stealth Twins with Small 2" by 9" ventral
 Small 2" by 9" Ventral
Kick Fin 5-3/4"
Single Fin Blk Box 7" Fiberglass Blue
Board Blkbox Uno 12'6"   
« Last Edit: August 16, 2016, 01:55:02 PM by ProBox-Larry »
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PonoBill

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #13 on: August 16, 2016, 02:12:49 PM »
I think you're inventing a force that doesn't exist, Larry, but I've given up on trying to talk Physics here.
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.

Larry Allison

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #14 on: August 16, 2016, 02:24:56 PM »
I think you're inventing a force that doesn't exist, Larry, but I've given up on trying to talk Physics here.

Bill, Please share, if I am using a word out of contexts.
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