twin-fins-or-more-on-a-race-board/so it begins

[Larry Allison]

All this debating cracks me up because it shows that most don't even know how a paddleboard moves thru water and what the function of a fin is and does, LOL but yet argue points that make no sense in the real world of Mother Nature. The last few days I have received some PMs from people sending me information about what some companies are posting about Fin Function and Performance on how to pick the right fin, LOL! Sometimes it's best not to say anything then posting Koolaid that the consumers are smarter then the Manufacturing sector.  I experienced the same in Windsurfing but yet the best riders in the world later rode my fins, proof is in the Pudding, LOL!

Thank you Ukgm, Ponobill, Bean, Luc, Burchas, Brodog and Stoneaxe to name a few that stepped up to Infinity and Beyond.

Thank you Ukgm for doing the work of showing what we simple people already experience. Yes since a year ago I have created a few new designs that increase the speed numbers more so because of the request from the consumers and some pros that are looking and now learning the advantage of multiple fins. Yes in simple terms, In the World of Standup riding a Single Fin which is a Pivot point along with a balancing act with a small range of reaction that tires you out. Or a multiple fin set-up which takes the balancing act out with a larger range of reaction and aiding in other aspects to better your water experience.

Yes it is a changing world for sure from 8 years ago since I started this push of multiple fins to now where the board designs scream Multiple fins even more so because the boards are higher on water putting the fin dynamics more in play from the boards of yesterday that were water subs that you almost didn't need a fin, LOL!

I am here to help people push their experience on the water which is my Passion which I am blessed to do myself. So if a old guy like me can ride a board 23 wide it tells you I am not a Travis Grant for sure but it's the equipment, lol!

 

[Eagle]

That sounds interesting. But here’s a couple of extra points:

1. Of course it would be possible to do the test with the paddlers blind to the fin setup. I’ve done experiments with much harder manipulations than that!

2. The principle you are trying to establish, surely, is whether the LA system is better than a single fin? .....

3. With fins, what aids you in one situation can hinder you in another. So just because a setup is faster in windless flat water when you are paddling alone does not mean it will be faster in real race conditions, or in the sea, etc. So ideally you’d test the setups with a variety of paddlers in a variety of conditions.

4. It is tough to test fins scientifically in such a way that the results are more than just marketing. .....

1. ..... Plus, as I say, even if you did, the answer needs to be specific to a paddler, not a sample. The latter is relevant for a manufacturers claims but the former more relevant for a paddlers performance needs.

2. No, it's to see whether its better for me and me alone. The benefits to a broader cross section aren't my concern and I don't need the benefits of penalties to be averaged out across a sample. That's not what I set out to prove. .....

3. Agreed and I have not claimed otherwise. .....

4. Yep, agreed. .....

The bottom line is would I use the Allison set up in my races, yes, some. Would I for all of them ? - no but gaining the objective understanding to make this decision is what I'm doing here. Having been asked to read and comment on both Starboards and Fanatics 2019 catalogues recently, I just can't bear any more pseudo science bullcrap.

Which races would you use that setup for and how would you come to that determination?

[ukgm]

That sounds interesting. But here’s a couple of extra points:

1. Of course it would be possible to do the test with the paddlers blind to the fin setup. I’ve done experiments with much harder manipulations than that!

2. The principle you are trying to establish, surely, is whether the LA system is better than a single fin? .....

3. With fins, what aids you in one situation can hinder you in another. So just because a setup is faster in windless flat water when you are paddling alone does not mean it will be faster in real race conditions, or in the sea, etc. So ideally you’d test the setups with a variety of paddlers in a variety of conditions.

4. It is tough to test fins scientifically in such a way that the results are more than just marketing. .....

1. ..... Plus, as I say, even if you did, the answer needs to be specific to a paddler, not a sample. The latter is relevant for a manufacturers claims but the former more relevant for a paddlers performance needs.

2. No, it's to see whether its better for me and me alone. The benefits to a broader cross section aren't my concern and I don't need the benefits of penalties to be averaged out across a sample. That's not what I set out to prove. .....

3. Agreed and I have not claimed otherwise. .....

4. Yep, agreed. .....

The bottom line is would I use the Allison set up in my races, yes, some. Would I for all of them ? - no but gaining the objective understanding to make this decision is what I'm doing here. Having been asked to read and comment on both Starboards and Fanatics 2019 catalogues recently, I just can't bear any more pseudo science bullcrap.

Which races would you use that setup for and how would you come to that determination?

For now, I would use the set up for the conditions I tested in which would be uncomplicated flatwater events. I haven't got the information or the data to know if this would be useful in other water states. I like to look at this testing as a stepping stone. Larry's intuition, as good as it is, won't beat a computer CFD package as an optimisation method though and I personally believe that further refinement using such tools could lead to further gains using the concept. I haven't got the time for that so I'm keeping things simple for now.

I'm purely interested in what can this do for me. To that end, my next port of call is to try it in slightly rougher conditions but I'd also like to try the ventral on its own with something like a Black Project Tiger on the back (whose aspect ration is optimised by computer for the speeds I'm personally racing at) to pick up on Area 10's point about whether the roll and yaw stability is where most of the gains are coming from. In some ways, it's like a process of elimination. I may well be shopping for my next board next month and I'd like to know how many fins its going to have !

[Luc Benac]

I'd also like to try the ventral on its own with something like a Black Project Tiger on the back to pick up on Area 10's point about whether the roll and yaw stability is where most of the gains are coming from. In some ways, it's like a process of elimination.

Isolating the effect of the twins would be a great demonstration in both flat and choppy water.

I have run the ventral with the 6"Stinger (flat)  or the 7" Stinger (choppy) only on my Whiplash and was quite please.
It looks like in September I could receive a Stealth kick = 4" deep and plan to run the full Stealth  kick and twins on flat water.

[PonoBill]

You can do some simple instrumentation that might give you useful data. Most important is speed changes. I don't really mean acceleration, which is easy to measure, but the curve of instantaneous speed, which is a trifle harder. I used an Eagle Tree systems datalogger--the new version is $69--and a free-spinning propeller that triggered a hall-effect sensor 24 times per shaft rotation.  Theoretically you could use GPS and accelerometers to do the same thing, but I found both the sample frequency and sensitivity obscured information I wanted to see.

Specifically, I wanted to see the acceleration curve, the peak speed, and the deceleration curve. I was testing paddles and stroke, but if I wanted to see what a set or fins were doing I'd want to see the same data. I think some fins let a paddler reach a higher speed because they do a better job of converting off-center vectored thrust into centerline acceleration. But if they do that at the expense of a lot of drag, or added turbulence at higher velocity, then the speed curve will be shaped differently and the area under the curve will be different. Average distance traveled will be different.

Using my primitive Paddle Pod I realized that the speed curve is complex and there's no such thing as glide. Just a curve for acceleration, a peak speed, and deceleration. Acceleration in the first few inches of the stroke is rapid, but it tails off before maximum speed is reached. Deceleration is also rapid as soon as the stroke ends, and tails off more slowly as speed drops. If there is any such thing as glide it happens only when a paddler strokes with such a slow cadence that the board almost comes to a stop.

The curve is different for high vs. low cadence--the high acceleration in the beginning of the stroke does not occur since the blade speed and the board speed ate more closely matched.

[Luc Benac]

So I am hoping to try on the low volume Whiplash:
1) Abuelo ventral with Aercor centre (soon)
2) Stealth kick and twins (should be able to receive a Stealth kick from a generous Zoner in September)

I usually do not have a problem with tracking. For me it is all about quartering and side chop while maintaining speed and a strong stroke.

[PonoBill]

Aeorcor works as well or better on my old Blackfish for downwinders. Doesn't seem fast though for flatwater. Too much tail wagging. Maybe if I cleaned up my stroke...

[Luc Benac]

Doesn't seem fast though for flatwater. Too much tail wagging.

I usually do not have a problem with tracking. For me it is all about quartering and side chop while maintaining speed and a "strong" stroke.
I will have to see the combination as the Aercor on its own might not work on flat but with the ventral, I am curious.

[ukgm]

1) Theoretically you could use GPS and accelerometers to do the same thing, but I found both the sample frequency and sensitivity obscured information I wanted to see.

2) Specifically, I wanted to see the acceleration curve, the peak speed, and the deceleration curve. I was testing paddles and stroke, but if I wanted to see what a set or fins were doing I'd want to see the same data.

3) I think some fins let a paddler reach a higher speed because they do a better job of converting off-center vectored thrust into centerline acceleration. But if they do that at the expense of a lot of drag, or added turbulence at higher velocity, then the speed curve will be shaped differently and the area under the curve will be different.

4) Using my primitive Paddle Pod I realized that the speed curve is complex and there's no such thing as glide. Just a curve for acceleration, a peak speed, and deceleration. Acceleration in the first few inches of the stroke is rapid, but it tails off before maximum speed is reached.

5) Deceleration is also rapid as soon as the stroke ends, and tails off more slowly as speed drops. If there is any such thing as glide it happens only when a paddler strokes with such a slow cadence that the board almost comes to a stop.

6) The curve is different for high vs. low cadence--the high acceleration in the beginning of the stroke does not occur since the blade speed and the board speed ate more closely matched.

1) You'd be amazed as how good the humble iPhone is for this too. I can get data sampling from using its built in sensors at 200Hz+. For the stuff I did here, I didn't go above 50Hz for now. The raw data file is frankly enormous.

2) The 'rowinginmotion' app spent a lot of time trumpeting this importance for rowing too. I didn't use this app here but i have done before. I actually prefer the raw data CSV file from an iPhone as it gives me 30 different metrics to drill into.

3) I agree completely. I have suspicions that the fluid management and drag are not always consistent with each other when comparing two fins. Deceleration is non-linear and its why my testing is aligned to speed ranges that I would personally race at for around 60-90 minutes. If people were selecting equipment for longer or shorter racing distances, I would suggest they change their tests accordingly.

4) Larry Cain had a nice article on his old blog page about this when he borrowed some tech from his C1 coaching day job to try it with a SUP board (and compared it to Jim Terrell). It's about profiling when comparing athletes in general and relative comparisons when optimising an athlete in particular. Put simply, I've had a few friends ask me what's fastest but all I can tell them is 'it depends'.....

5) Yep, I agree. My profile is more akin to Larry's than more of a pure sprinter like Terrell. Interestingly, I see similar characteristics in my cycling too which suggests how important physiological profiling and biomechanics are when you're trying to take an athlete and make them faster (and then how unique that is in comparison to another).

6) Yep, the Terrell vs Cain blog article nicely illustrated this (if you haven't seen it yet).

[Larry Allison]

Here is a recent conversion done from a Probox Tech Installer in Washington. Thought I would share the review from the owner of this board. THese are customers that seek me out when they want to better their water experience.


Marcus Chiu
Marcus Chiu · Friends with Sup Race Fins and 5 others
I tried my new fin setup, first with the Dolphin Keel and Ventral, then ProBox twin and Ventral.
Dolphin Keel was better than stock fin for stability, but the ProBox twin was way more stable and tracked like it was in rails.
I felt more confident and was able to focus more on paddling than keeping my balance with a faster top speed.
I look forward to putting more time on the water with this new setup.
Thanks Sean Thomas / Echo Composite for the install.🤙

[Larry Allison]

Same board showing Box placement from stock placement.

[Bean]

Hey Larry, have I been installing my boxes backwards?

[Larry Allison]

Hey Larry, have I been installing my boxes backwards?

Bean if the fin sets in a concave which is Rare in this case or on a flat then screws face the inside to allow the inner changeable Probox Cant bringing the fin vertical.

Notice you see more of side of the fin with the Cant in this picture, that is what water sees which slows you down. 

[Larry Allison]

Hey Larry, have I been installing my boxes backwards?

When you have "V" in the bottom or flat then screws are to the outside allowing the Probox inner changeable inserts to bring the fin Vertical like shown in this picture. Notice you see NO side of the fin looking down in this picture which is why water does not react to the flow from nose to tail.

[Larry Allison]

Hey Larry, have I been installing my boxes backwards?

In this picture the same fin is put in like a SURFBOARD setup flat side in. Notice the Toe in front reacts with the water flow coming from nose to tail. This is all wrong in a Probox Race Twin World.