Author Topic: Black fish, three fin vs. one  (Read 16022 times)

Eagle

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Re: Black fish, three fin vs. one
« Reply #15 on: August 28, 2016, 05:36:37 PM »
Tried a LA 4 fin modified 25" BW Eradicator with only the ventral and small centre fins in place.  The board was extremely stable and very fast without the side twins.  Can see adding more fins if you really required crazy side to side stability on flat.  But in most cases - would just use the OEM single fin set-up for up down AW use.  The 25 is a nice stable board already.

NH was the original owner of the board before it was modified by a zoner.  Up in Squamish a year ago - Norm used that board with the OEM fin and he just planed and surfed that board with complete ease.  It was crazy to see how easy he pulled away from all of us.  And he told us he was slow compared to Connor and Kai.   :o
Fast is FUN!   8)
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stoneaxe

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Re: Black fish, three fin vs. one
« Reply #16 on: August 28, 2016, 06:46:50 PM »
Ventral is great in flat out speed sprint on flatwater but once you get water movement I feel the same...negative outweighs any positive.
Bob

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burchas

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Re: Black fish, three fin vs. one
« Reply #17 on: August 28, 2016, 10:02:56 PM »
from my experience i have been playing with 3 fins for a while now but just fitted the ventral. i could not feel hardly any difference with the rear sides in, the ventral made a small positive difference on the flat but quite a negative difference on the ocean. Considering my board is 21" wide they are quite stable so perhaps it is not so noticeable. The rear fins have been proved to slow the board down it seams and getting extra stability all the way at the tail is never going to be that effective which is why i think the ventral makes a lot more sense in the flat but not in a moving ocean.

I would like to know what are the negatives you experience with the ventral on open water? What is the measurements and shape of your ventral.

Fine tuning took some time, long time. But after several months of back and forth with Larry, going from over fined to under fined with several fin configurations, I now have a 4 fin setup that works better than any single, center/ventral configuration in most cases for me.

4x10 twins, 6" stinger and 2x9 ventral. I found it to be the best combination of speed and balance, being able to commit to my best stroke on my high cadence (50 spm) without having to worry about loosing balance.

I usually use variety of center fins with small ventral for my day to day, but when I need to preform, my 4 fin setup is my go to choice.

I do have my winter setup with the 7" stinger and the slower 2.5x12 ventral, but it's a small price to pay considering the other option is 35F water.
in progress...

ukgm

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Re: Black fish, three fin vs. one
« Reply #18 on: August 29, 2016, 02:41:51 AM »
If the testing were done blind such that the rider didn't know the fin setup, then we'd be talking a bit more testing rigour. This and many many runs would be a way to normalize the rider's effort and remove any bias.

Once we get solid empirical results then we can get on with figuring out the why.

You can't really get that with equipment interventions though so you have to rely on typical statistical techniques to tease out whatever robustness you can find.
Certainly, blind trials would be virtually impossible with paddles and boards. But with most fin setups it should easily be possible.

The placebo effect is so strong that tests that don't take it into account are highly suspect. Notice how whenever you get a new board you seem to set a PB soon afterwards? That's most likely the placebo effect in action. Without even being conscious of it, you are cleaning up your technique and trying that 0.5% harder in the belief that your new board or paddle will make you go faster.

I've noticed that the larger the sum of money I've spent, the quicker that new PB happens!

And yes, it could also be that equipment is getting better. But I'm talking about effects above and beyond that.

Trials should really be conducted with several paddlers in order to minimise the placebo effect. Our Australian friends (PT and crew) did an interesting comparison of 14fters of this type a few years ago.

Placebo can often be teased out as its magnitude isn't generally reliable. In other words, do enough runs and you'll see something is wrong (although this could be construed instead as a poor experiment design or conditions).

Using several paddlers may help reduce placebo (or might just create variable levels of individual bias) but might not help as that will only tell you what is good for that specific sample (rather than what you really want to know - i.e. what is good for me). The reality is to just crank out enough runs and really look hard at the stats. Test/retest strategies might be worthwhile too.

Area 10

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Re: Black fish, three fin vs. one
« Reply #19 on: August 29, 2016, 03:51:28 AM »
I repeat, the best way is to use several paddlers. Period.

I've earned my living for the last 30 years doing scientific experiments on human performance. If you want your results to be applicable to a population of people rather than to just one, then you need to test a representative sub sample of that population of people.

You can establish proof of principle with a N of one (and I've done that too) for eg. creating a particular method. But that isn't much help here: The fin setup that might make one person faster might make another slower. This happens often with SUP: if you are on a board that is too tippy for you, or your technique is not good, you can sometimes go faster by using a large area fin with a wide base. But once you improve your balance and technique, you will probably find that a smaller area fin with a narrower base will be faster for you.

Using a group of people to test will usually ameliorate any placebo effect since people will differ greatly in terms of their beliefs. One person who is convinced that X fin is fastest will still be faster using that fin so repeat testing doesn't really solve the problem: testing a group of people does (and using multiple runs, balancing the orders of them across the group using eg. a Latin Square design).

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Re: Black fish, three fin vs. one
« Reply #20 on: August 29, 2016, 05:40:20 AM »
I repeat, the best way is to use several paddlers. Period.

I've earned my living for the last 30 years doing scientific experiments on human performance. If you want your results to be applicable to a population of people rather than to just one, then you need to test a representative sub sample of that population of people.

You can establish proof of principle with a N of one (and I've done that too) for eg. creating a particular method. But that isn't much help here: The fin setup that might make one person faster might make another slower. This happens often with SUP: if you are on a board that is too tippy for you, or your technique is not good, you can sometimes go faster by using a large area fin with a wide base. But once you improve your balance and technique, you will probably find that a smaller area fin with a narrower base will be faster for you.

Using a group of people to test will usually ameliorate any placebo effect since people will differ greatly in terms of their beliefs. One person who is convinced that X fin is fastest will still be faster using that fin so repeat testing doesn't really solve the problem: testing a group of people does (and using multiple runs, balancing the orders of them across the group using eg. a Latin Square design).

This all make sense and to emphasize the complexity of said tests you need to add one more complication: Different Boards.
Based on my discussions with Larry I know that different boards call for different setups. Metrics such as Tail volume, width and rocker and board overall volume and length will dictate the setup.

And than there is the complexity of open water testing. It's all nice and perfect when we test it in the flats but it's almost useless
for me as I rarely get to ride in these conditions.

Just for my own board I had about 20 combinations of setups:

  • 5 Center fins
  • 4 sets of twins
  • 2 ventrals

I'm not a numbers guy, but lets take the 20 combinations, add just the 5 most popular boards on the market, bring 5 paddlers
and lets test it in open water conditions. The end results is nice mixed salad :) not to mention it's a ridiculous undertaking.

For the time being I'll rely on my own tests and read other members tests results and then talk some more to Larry to get his
take on things and maybe suggest an approach.
in progress...

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Re: Black fish, three fin vs. one
« Reply #21 on: August 29, 2016, 07:27:38 AM »
Yes - up to a point.

I analysed the data from Robert's first group test, and PT Woody and crew's subsequent 14ft test. And I've conducted several of my own since. And I can tell you that the performance differences you'd find between different fin setups will be so small, over a large number of people, that it would be quite an enterprise to collect enough data to prove differences to normal scientific criteria. The effort and skill required would be pretty trivial for a professional researcher who has some funding behind them, but would be prohibitive for the average Joe paddler.

Does this mean that fin setups make no difference? Certainly not. It just means that a particular setup will suit one person but not another. And one board but not another. And some conditions but not others.

So, my advice is to try to understand some of the basics of what fins do, and fin design (which might take a couple of hours of research to establish), and then try some setups for yourself. Learn what is right for you and your boards by trial and error. And beware of anyone making very broad statements about how "good" a fin is, or how it will improve performance: "for whom, in what board, and in what conditions, and why?" are the questions you need to be asking them. If you don't get a clear and unambiguous answer then be suspicious, IMO.

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Re: Black fish, three fin vs. one
« Reply #22 on: August 29, 2016, 07:59:38 AM »
The other thing I've noticed is that all the testing done mostly speak to speed performance and neglect
to emphasize the other benefits of the 4 fin which are much easier to prove and more important to me.

To begin with, I didn't subscribed to the 4 fin setup due to improved speed. Although in my tests I did
find the setup to be marginally faster in most cases (but not all), at my level or where I see my self at, It would not worth the hassle.

The added stability, improved tracking, better handling in confused conditions and the ability to avoid close to surface obstacles (namely rocks) definitely worth the hassle, even if it did mean I have to take a slight hit on speed, which I don't 8). For my use case it's a no brainer.
in progress...

Board Stiff

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Re: Black fish, three fin vs. one
« Reply #23 on: August 29, 2016, 08:44:00 AM »
Empirical testing aside, what are the theoretical advantages/disadvantages of a 3 fin setup vs a single fin on a raceboard? I've never seen the multi-fin setup on anything other than a surf SUP before. Is it to improve performance in BOP or downwind races where some surfing is necessary? Or would it provide any benefits on flatwater too?

ukgm

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Re: Black fish, three fin vs. one
« Reply #24 on: August 29, 2016, 10:08:02 AM »
If you want your results to be applicable to a population of people rather than to just one, then you need to test a representative sub sample of that population of people.

......which is exactly why I said it wasn't necessary. The results of any evaluation in this case don't need to be applicable to a population. They only need to be a robust case study - i.e.  To know what is needed to be fastest for you (the paddler doing the testing for themselves). A sample group would be detrimental to that aim (in my view). Granted though, to a company themselves (or someone trying to prove the overarching concept), yep, I'm with you all the way - a large population study would be needed..... however, I suspect that you would not be able to obtain the statistically recommended sample size.

The other thing is using different board and fin combinations just won't help because no single design feature created in isolation will work wholesale statistically reliably. It's entirely plausible that a board with a heavy concavity (like an Allstar) may not benefit at all whereas something very flat may well benefit enormously.

As you know, I'm working on some fin testing at the moment but the real area of interest to me is whether you can start detecting measurable changes in performance with smaller and smaller incremental changes in equipment when field testing.

« Last Edit: August 29, 2016, 10:36:04 AM by ukgm »

Eagle

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Re: Black fish, three fin vs. one
« Reply #25 on: August 29, 2016, 11:10:24 AM »
The fin setup that might make one person faster might make another slower. This happens often with SUP: if you are on a board that is too tippy for you, or your technique is not good, you can sometimes go faster by using a large area fin with a wide base. But once you improve your balance and technique, you will probably find that a smaller area fin with a narrower base will be faster for you.

^^^
We do plenty of upwind DW and loop routes in the ocean - and conditions change all the time.  It seems for DW in waves a 4 fin set-up will not play nice.  Even using a single fin with too much hold and tracking -> is a dangerous broaching hazard and detriment.  So we go with the smallest fin possible that provides sufficient hold yet releases when you want.  Interestingly on a narrow board like our AS23 - secondary stability improves tremendously using a small single fin once your mind and body adapt.

Once you learn how to ride a narrow board - you want less fin so you can exert more control when you want.  Being over finned prevents this.  With time - initial stability also improves dramatically.  Our AS23 has been the best purchase we have made because it has forced us to move outside our box and learn new skills - and how better to apply power.  We simply test this via our own sprint and 5 mile GPS time trials.  Those are the truly accurate ones.  There is no doubt our AS23 is plenty faster on flat than our Dominator -> in a sprint and over 5 miles.
Fast is FUN!   8)
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PonoBill

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Re: Black fish, three fin vs. one
« Reply #26 on: August 29, 2016, 01:15:08 PM »
Im honestly not too interested in what works for most people, I only care about what works for me. When I was testing paddles long ago to try to make a better one that wasn't so, buy Im not going to sell boards or fins. Its just me,me,me,me.

In that selfish vein I think my results with the three fin setup on the Blackfish was quite significant--for me. It wasn't the result i expected or wanted. Now Im going to have to add a ventral fin and see what that does. As I've said before, listening to Larry's technical explanation of what his fins do gives me heartburn, but I certainly can't argue about the results.
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Re: Black fish, three fin vs. one
« Reply #27 on: August 29, 2016, 01:58:38 PM »
This gives me a chuckle, Pono, as I remember when I lined up next to you before the PPG start last year.  I believe your exact quote was:  "why'd you put all those fins on your board?" (but I can't capture the hint of disdain in your tone.)
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SlatchJim

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Re: Black fish, three fin vs. one
« Reply #28 on: August 29, 2016, 02:38:03 PM »
Who won between you two?   :)

supuk

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Re: Black fish, three fin vs. one
« Reply #29 on: August 29, 2016, 02:46:31 PM »
from my experience i have been playing with 3 fins for a while now but just fitted the ventral. i could not feel hardly any difference with the rear sides in, the ventral made a small positive difference on the flat but quite a negative difference on the ocean. Considering my board is 21" wide they are quite stable so perhaps it is not so noticeable. The rear fins have been proved to slow the board down it seams and getting extra stability all the way at the tail is never going to be that effective which is why i think the ventral makes a lot more sense in the flat but not in a moving ocean.

I would like to know what are the negatives you experience with the ventral on open water? What is the measurements and shape of your ventral.



the ventral i have recently been using is 2 x 6 and found on the ocean you are very much effected by what the currents are doing. If you are not going straight up or down you get drifted sideways fast and it takes more effort than its worth to correct it. Its like flying a plane in winds if you one to go in a tight line towards something the board does not necessarily want to be pointed straight  directly at it in a current and the ventral stops this. We also get quite a bit of back wash of our seep beaches and having swell moving at you for booth sides took me by surprise a lot more with the ventral than without.

Im pretty sure the placebo effect is stronger than the difference the fins makes in most situations.

 


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