Author Topic: Which fin on your DW board?  (Read 15599 times)

pdxmike

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Re: Which fin on your DW board?
« Reply #15 on: August 29, 2016, 05:26:03 PM »
Area 10,
Check your facts.


It would be nice to know who you are.  Are you an owner of this company? Employee?


And I don't know why you told Area 10 to "check your facts".  You countered several things he didn't say, but not really anything that he did say.
« Last Edit: August 30, 2016, 06:02:31 AM by Admin »

Larry Allison

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Re: Which fin on your DW board?
« Reply #16 on: August 29, 2016, 05:30:51 PM »
Check out these fins from Cape Hatteras. The guys that make these fins are the real deal. Engineers that design the foils using fluid dynamics modeling. Then they are reproduced precisely using cnc manufacturing.

http://cncfins.com/

Travis Grant placed 2nd in the Maui to Molokai with their fin.

http://www.maui2molokai.com/2016-maui2molokai-results/

Lots more stuff on their Facebook page.

https://www.facebook.com/cncfins/photos/a.828467717189497.1073741829.828126137223655/988617811174486/?type=3

https://www.facebook.com/cncfins/posts/1013599102009690
Fins shaped like that have been around for a while now (eg. the FCS Weedless). But they haven't proved particularly popular. They don't really give you any special benefit in any way, excepting that they are quite low surface area.

Several companies have taken windsurf shapes and turned them out for SUPs. It doesn't work well IMO because the speeds and forces at work, and the way the board is used, is totally different in SUP compared to windsurfing. If you want to look at fins from another discipline, you are much better off looking at surfboard fins IMO.

No-one is going to be applying fluid dynamics software to SUP fin designs because the software doesn't exist for SUPs. Everyone is just using various forms of trial and error, from a starting point that is little more than a guess based on experiences from wildly different vessels and applications (boats, kayaks, windsurfers, surfboards etc). So IMO beware of people telling you that their products are the result of the appliance of science because I don't think that for SUP the scientific principles exist, never mind the data to apply them. It's just another marketing strategy. The SUP world is, sadly, full of instant gurus. Buyer beware. The only real way to tell if a fin is right for you and your board is to try one. Personal preferences are so particular anyway: what I am convinced is best, and improves my performance, might be torture for you and ruin yours.

Agree with Area10, The CNC fins are very specific for downwind riding a bump where water is pushing you from behind and very little Paddle stroke is used for power. That is why Future Fins uses a cutaway fin for the same reason easy PIVOT TURNING BUTTTTTT!!!! when you hit the flats and swell city starts to hit from all sides these fins are the biggest joke like cutaway fins and you go swimming. Again people play off this foil section cad program crap to sell product. Listen to my interview https://soundcloud.com/stand-up-paddle-the-world/larry-allison-master-of-racing-fins  and I talk about this over tech engineering hype that means nothing except a over priced piece of circuit board material (G-!0).
« Last Edit: August 29, 2016, 05:34:17 PM by ProBox-Larry »
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Larry Allison

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Re: Which fin on your DW board?
« Reply #17 on: August 29, 2016, 05:48:49 PM »
Ok, please explain to me how a fin creates "lift" as you claim, in flat water paddling, and what amount of force this "lift" typically amounts to in a SUP moving at 5 mph in still water and no wind.

If you are the real deal then you should easily be able to explain this claim- taken from your rant above - in a way that the average reader of this forum will understand. And then we can measure this for ourselves and see if your claim is right. I'll even pay full price for the fin myself. If your claim is correct, then I will make sure I say so in this forum perfectly clearly. However if I find your claim to be false or misleading, then I hope you will equally accept that I will also give details of that here, and that you will give me my money back.

You can create lift by a little thicker foil in the thickest part of the fin at low speeds but not without pushing water. So the fin has to be short enough in depth which water sees as drag to balance out the drag or push of water. The 2" Ventral fin creates a slight lift which is noticed by the water wake coming off the nose of your board. With a Ventral fin the water wake is small, without the Ventral fin in the same board with the same or close paddle stroke the water wake becomes bigger meaning the board is pushing water. This happened on some boards we tested with multiple riders. But in the case of CNC I agree with Area10, they did not take in account the depth of their fins and determining lift in a specific downwind situation which is not actuate to how they are promoting their fins in a Sup market use normally, HYPE with G-10 on top which kills me, LOL!!!!!
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DavidJohn

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Re: Which fin on your DW board?
« Reply #18 on: August 29, 2016, 08:26:54 PM »

Ok, please explain to me how a fin creates "lift" as you claim, in flat water paddling, and what amount of force this "lift" typically amounts to in a SUP moving at 5 mph in still water and no wind.



I agree.. but IMO there are times downwinding that you can feel lift from a fin and you don't need to be going very fast.. When you opposite rail a board across a swell when planing and sometimes not even planing but surging you can feel the upwind rail wanting to lift and doing this can help to cut across the wave and wind and I often use this technique to hold my line when the gust blow me more offshore and out to sea..

Some fins seem to do it better/more than others.. IMO fins like that Mirage shape do it more (but I haven't actually tried that particular one) but although that lift feeling can be seen as a good thing sometimes I don't like it because when you get your DW board up to max speed dropping into a huge runner/trough and the board is flat and not railing left or right you can feel the fin tiring to left a rail left or right or even both in a wiggling motion and the board becomes unstable to the point where you get bucked off.. I've been bucked off a few times..

It's a similar feeling to heading off the wind on a windsurfer with a pointer fin that too big for the wind strength and conditions..

Another reason I like the more donphin shape over the Mirage shape is when your fin touches in shallow water.. The pointy tip like on the Mirage tends to dig and grab rather than slide like the dolphin and Arecor fin even thought the Mirage shape has plenty of rake..

IMO the best fin it one that feels like it's not even there.. It does its job with tracking.. stability and turning.. but doesn't give too much tracking or stability.. turn too much or feel slow..

But how much tracking.. stability or turning ability is just right might vary from person to person.. There's a big difference between science and seat of your pants with what works best... IMO..   8)

coldsup

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Re: Which fin on your DW board?
« Reply #19 on: August 29, 2016, 08:30:43 PM »
Check out these fins from Cape Hatteras. The guys that make these fins are the real deal. Engineers that design the foils using fluid dynamics modeling. Then they are reproduced precisely using cnc manufacturing.

http://cncfins.com/

Travis Grant placed 2nd in the Maui to Molokai with their fin.

http://www.maui2molokai.com/2016-maui2molokai-results/

Lots more stuff on their Facebook page.

https://www.facebook.com/cncfins/photos/a.828467717189497.1073741829.828126137223655/988617811174486/?type=3

https://www.facebook.com/cncfins/posts/1013599102009690
Fins shaped like that have been around for a while now (eg. the FCS Weedless). But they haven't proved particularly popular. They don't really give you any special benefit in any way, excepting that they are quite low surface area.

Several companies have taken windsurf shapes and turned them out for SUPs. It doesn't work well IMO because the speeds and forces at work, and the way the board is used, is totally different in SUP compared to windsurfing. If you want to look at fins from another discipline, you are much better off looking at surfboard fins IMO.

No-one is going to be applying fluid dynamics software to SUP fin designs because the software doesn't exist for SUPs. Everyone is just using various forms of trial and error, from a starting point that is little more than a guess based on experiences from wildly different vessels and applications (boats, kayaks, windsurfers, surfboards etc). So IMO beware of people telling you that their products are the result of the appliance of science because I don't think that for SUP the scientific principles exist, never mind the data to apply them. It's just another marketing strategy. The SUP world is, sadly, full of instant gurus. Buyer beware. The only real way to tell if a fin is right for you and your board is to try one. Personal preferences are so particular anyway: what I am convinced is best, and improves my performance, might be torture for you and ruin yours.

Agree with Area10, The CNC fins are very specific for downwind riding a bump where water is pushing you from behind and very little Paddle stroke is used for power. That is why Future Fins uses a cutaway fin for the same reason easy PIVOT TURNING BUTTTTTT!!!! when you hit the flats and swell city starts to hit from all sides these fins are the biggest joke like cutaway fins and you go swimming. Again people play off this foil section cad program crap to sell product. Listen to my interview https://soundcloud.com/stand-up-paddle-the-world/larry-allison-master-of-racing-fins  and I talk about this over tech engineering hype that means nothing except a over priced piece of circuit board material (G-!0).

Larry, you are basically saying my Futures Cali DW fin might be fine on the wave but not so great in between the bumps?

Larry Allison

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Re: Which fin on your DW board?
« Reply #20 on: August 29, 2016, 08:41:08 PM »
Check out these fins from Cape Hatteras. The guys that make these fins are the real deal. Engineers that design the foils using fluid dynamics modeling. Then they are reproduced precisely using cnc manufacturing.

http://cncfins.com/

Travis Grant placed 2nd in the Maui to Molokai with their fin.

http://www.maui2molokai.com/2016-maui2molokai-results/

Lots more stuff on their Facebook page.

https://www.facebook.com/cncfins/photos/a.828467717189497.1073741829.828126137223655/988617811174486/?type=3

https://www.facebook.com/cncfins/posts/1013599102009690
Fins shaped like that have been around for a while now (eg. the FCS Weedless). But they haven't proved particularly popular. They don't really give you any special benefit in any way, excepting that they are quite low surface area.

Several companies have taken windsurf shapes and turned them out for SUPs. It doesn't work well IMO because the speeds and forces at work, and the way the board is used, is totally different in SUP compared to windsurfing. If you want to look at fins from another discipline, you are much better off looking at surfboard fins IMO.

No-one is going to be applying fluid dynamics software to SUP fin designs because the software doesn't exist for SUPs. Everyone is just using various forms of trial and error, from a starting point that is little more than a guess based on experiences from wildly different vessels and applications (boats, kayaks, windsurfers, surfboards etc). So IMO beware of people telling you that their products are the result of the appliance of science because I don't think that for SUP the scientific principles exist, never mind the data to apply them. It's just another marketing strategy. The SUP world is, sadly, full of instant gurus. Buyer beware. The only real way to tell if a fin is right for you and your board is to try one. Personal preferences are so particular anyway: what I am convinced is best, and improves my performance, might be torture for you and ruin yours.

Agree with Area10, The CNC fins are very specific for downwind riding a bump where water is pushing you from behind and very little Paddle stroke is used for power. That is why Future Fins uses a cutaway fin for the same reason easy PIVOT TURNING BUTTTTTT!!!! when you hit the flats and swell city starts to hit from all sides these fins are the biggest joke like cutaway fins and you go swimming. Again people play off this foil section cad program crap to sell product. Listen to my interview https://soundcloud.com/stand-up-paddle-the-world/larry-allison-master-of-racing-fins  and I talk about this over tech engineering hype that means nothing except a over priced piece of circuit board material (G-!0).

Larry, you are basically saying my Futures Cali DW fin might be fine on the wave but not so great in between the bumps?

No my friend, What I am saying is your fin is ok when being pushed by mother nature from the rear of the board which involves little to a few paddle strokes. But when your conditions change that involve a higher count of paddle strokes now power coming from the front of your board the Cutaway fin falls by lack of push because of a small base line to push off of to move forward and pick up speed. Along with tail drift left to right due to the pivot plan shape of the fin causing the board to Yaw like crazy which now you are fighting the fin to go straight to gain speed for stability. Hope this helps explains my self better. Mahalo
« Last Edit: August 29, 2016, 08:42:53 PM by ProBox-Larry »
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coldsup

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Re: Which fin on your DW board?
« Reply #21 on: August 30, 2016, 12:15:43 AM »


No my friend, What I am saying is your fin is ok when being pushed by mother nature from the rear of the board which involves little to a few paddle strokes. But when your conditions change that involve a higher count of paddle strokes now power coming from the front of your board the Cutaway fin falls by lack of push because of a small base line to push off of to move forward and pick up speed. Along with tail drift left to right due to the pivot plan shape of the fin causing the board to Yaw like crazy which now you are fighting the fin to go straight to gain speed for stability. Hope this helps explains my self better. Mahalo
[/quote]

Thanks Larry - got you this time.

Bean

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Re: Which fin on your DW board?
« Reply #22 on: August 30, 2016, 07:39:37 AM »
Why are Reynolds posts being deleted...what a bunch of narrow minded sheep

mrbig

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Re: Which fin on your DW board?
« Reply #23 on: August 30, 2016, 08:26:13 AM »
Don't have a dog in this er discussion..

But, there does seem to be resistance to open, honest, dialogue that I find disturbing.

Don't think Travis would be using a fin that wasn't working better for him..


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Quickbeam

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Re: Which fin on your DW board?
« Reply #24 on: August 30, 2016, 08:26:43 AM »
Larry and Area 10,
you guys can't seem to take an opinion that is different than your own as my posts have been deleted twice. so much for fair open discussion forum. have fun with your fan club. too bad we couldn't actually share real information to help the sport progress, you provide a great disservice to all SUP racers and downwinders by spouting pseudo science voodoo baloney.   so i ask you...i'll post my reply one more. time.. do you have the balls to let it up and let people ask questions? Keith cncfins.com

I see that your posts have been deleted, but I think you are blaming the wrong people. As far as I know, Area 10 and Larry would not have the ability to delete your posts. I'm pretty sure it must have been the Admin. that deleted them. Not sure why.
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Eagle

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Re: Which fin on your DW board?
« Reply #25 on: August 30, 2016, 08:32:11 AM »
Some fins seem to do it better/more than others.. IMO fins like that Mirage shape do it more (but I haven't actually tried that particular one) but although that lift feeling can be seen as a good thing sometimes I don't like it because when you get your DW board up to max speed dropping into a huge runner/trough and the board is flat and not railing left or right you can feel the fin tiring to left a rail left or right or even both in a wiggling motion and the board becomes unstable to the point where you get bucked off.. I've been bucked off a few times.....

..... IMO the best fin it one that feels like it's not even there.. It does its job with tracking.. stability and turning.. but doesn't give too much tracking or stability.. turn too much or feel slow..

But how much tracking.. stability or turning ability is just right might vary from person to person.. There's a big difference between science and seat of your pants with what works best... IMO..   8)
^^^
Interestingly the M-14 skitters when planing - but the Bullet 14V2 does not skitter.  My interpretation of this was because the M-14 has a flat bottom at the tail - vs the Bullet a panel vee.  The M-14 also planes late and abruptly - while the Bullet sooner and easier.  This was attributed to the flat M-14 midsection - vs the single concave Bullet. 

The fastest though was with the old carbon Bullet 14V1 that has a double concave and panel vee.  That board planes the earliest and the most and is crazy fast.  All boards were using the SIC 8.3 fin in short period waves in about 20 kts.  Oddly the Bullet 14V1 was more tender side to side than the Bullet 14V2.  But for fins - just try different ones and use what keeps you dry and stable and planing at top speed.  Most importantly though - ones that allow you to turn when you want and do not broach.  Basically a fin that does not hinder you in any way.  Or the least anyways.

And yes - would be interesting to see Reynold's actual response at this point.
Fast is FUN!   8)
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Larry Allison

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Re: Which fin on your DW board?
« Reply #26 on: August 30, 2016, 08:34:59 AM »
Larry and Area 10,
you guys can't seem to take an opinion that is different than your own as my posts have been deleted twice. so much for fair open discussion forum. have fun with your fan club. too bad we couldn't actually share real information to help the sport progress, you provide a great disservice to all SUP racers and downwinders by spouting pseudo science voodoo baloney.   so i ask you...i'll post my reply one more. time.. do you have the balls to let it up and let people ask questions? Keith cncfins.com

Reynolds, Not sure why your posts are deleted but don't tell me I can not take a opinion because I have done what you are doing in the 80's and I Windsurfed working with some of the best. Now I Standup Paddle and ride and test everything I make along knowing what's wrong and right. So if you don't like my opinion so be it but don't accuse me of spouting pseudo science voodoo baloney which is exactly what you are doing. I have been doing this for over 40 years probably longer than you have been alive.
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Area 10

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Re: Which fin on your DW board?
« Reply #27 on: August 30, 2016, 09:55:34 AM »
Larry and Area 10,
you guys can't seem to take an opinion that is different than your own as my posts have been deleted twice. so much for fair open discussion forum. have fun with your fan club. too bad we couldn't actually share real information to help the sport progress, you provide a great disservice to all SUP racers and downwinders by spouting pseudo science voodoo baloney.   so i ask you...i'll post my reply one more. time.. do you have the balls to let it up and let people ask questions? Keith cncfins.com

I see that your posts have been deleted, but I think you are blaming the wrong people. As far as I know, Area 10 and Larry would not have the ability to delete your posts. I'm pretty sure it must have been the Admin. that deleted them. Not sure why.
Quickbeam is right, and you need to calm down, friend. I can't speak for Larry, but I certainly don't have the ability to delete posts on this forum - and I doubt that Larry can either. If deletions have occurred it will probably be because you have broken forum rules. For instance, you have quoted advertising material from your website in one of your posts, and unless you are a site sponsor this is probably not permitted. You need to direct your anger - and questions - about this matter to Admin.

However, I note that you have avoided answering a straightforward question about the physics of something that you claimed in a previous post, and it seems to me that you are now trying to bluster your way out of this.

You will find that this forum is generally extremely open-minded to new ideas. In general we are a bunch of "early adopters", hence why we got into SUP from the very start. But being open-minded does not translate to being gullible. You have made a claim that your are bringing a superior knowledge of the fluid dynamics to fin design. And I am calling you on that. Please answer my original question to you (how does your fin generate "lift" in flat water, and what degree of force does that lift translate to?).

Getting aggressive with people on this forum won't make us back down. We are generally too experienced (ie. old, haha!) for that. In fact it will just stiffen our resolve. So I'd suggest you take a different approach because the one you are using currently is getting you nowhere.
« Last Edit: August 30, 2016, 10:05:20 AM by Area 10 »

Eagle

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Re: Which fin on your DW board?
« Reply #28 on: August 30, 2016, 11:06:49 AM »
However, I note that you have avoided answering a straightforward question about the physics of something that you claimed in a previous post, and it seems to me that you are now trying to bluster your way out of this.

You will find that this forum is generally extremely open-minded to new ideas. In general we are a bunch of "early adopters", hence why we got into SUP from the very start. But being open-minded does not translate to being gullible. You have made a claim that your are bringing a superior knowledge of the fluid dynamics to fin design. And I am calling you on that. Please answer my original question to you (how does your fin generate "lift" in flat water, and what degree of force does that lift translate to?).

Getting aggressive with people on this forum won't make us back down. We are generally too experienced (ie. old, haha!) for that. In fact it will just stiffen our resolve. So I'd suggest you take a different approach because the one you are using currently is getting you nowhere.
"Please answer my original question to you (how does your fin generate "lift" in flat water, and what degree of force does that lift translate to?)."

This seems like a fair question that deserves a response.
Fast is FUN!   8)
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PonoBill

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Re: Which fin on your DW board?
« Reply #29 on: August 30, 2016, 11:35:51 AM »
There's no doubt that fins develop lift, it's why they are shaped as they are. The question is in which direction the lift is being generated. The ability of a fin to keep a beard going straight is a function of lift. For a double foiled fin, any angle of attack other than straight on generates lift that corrects the skew. The lift is perpendicular to the fin, and as soon as the board is going straight it goes away--or more accurately is balanced by the flow on the opposite side of a fin. No one uses a single foiled fin, for the simple reason that it would constantly work to turn the board sideways to the direction of travel in the direction of the foil. Single foiled thrusters balance each other out when the board is flat and traveling straight. With the board turning they generate unbalanced lift due to akerman effect--the outer fin travels faster, in a wider arc than the inner fin which helps stabilize the tail a little. With one thruster buried in the face of a wave and the other waving in the air, the buried fin pulls the tail into the wave face and helps keep it from being shoved out.

But talking about lift raising the tail of the board or reducing drag is a little nutty. There is such a thing as keel and rudder lift, caused mostly by heeling a sailboat, and there might be some miniscule lift generated by a raked face--with the high density of water, it's tougher to discount even trivial surfaces at an angle to the direction of travel, but claiming to have calculation to support that is just silly. There's way too much going on for simple models to be meaningful.

I've seen a lot of strange force diagrams, and most of them are baloney. Treating a SUP board in isolation, on flatwater, with only a paddle for propulsion there is only one propulsive force being applied--that from the paddle--and it is being applied off-center to the board. If there were no fin the resultant force vector  would turn the board in circles and only the rail and board drag would resist that movement. So it's valid to talk about fin efficiency in resisting that vector and optimizing the propulsive force as forward movement--and that's all. There's no magic force being generated by the fin. If there were you could give your board a gentle shove and watch it accelerate away.

The complexity of the interaction between the board shape, fin locations, fin shapes, turbulent surface, various flavors of drag, and weight shifting make explanations dubious, and I doubt anyone is really spending the money to develop anything authoritative.  I'm a lot more convinced by "we tried this and it works" than I am by any claim of science.
« Last Edit: August 30, 2016, 11:53:06 AM by PonoBill »
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