What is the GP style paddle called

Wow, very interesting. Questions.
Live and learn on pnet. I had never heard of or seen such a paddle before.



What is the purpose of that sharp ridge, and why and when would you use the ridged side vs. the smooth side?

I Asked That Very Question
in a thread a while back. The answer I got was that the ridge prevented flutter. Since my GPs don’t flutter it’s not the paddle for me.

I was making wood chips before
I started paddling and I think they look cool, so …

What is the power face?
If the ridged side is supposed to be the power face, that sharp ridge seems to be a rather primitive and overly aggressive means of preventing flutter via what we (somewhat confusingly) today call camber or dihedral. My first assumption was that the ridged side was the back face.



The ridge must degrade slicing and feathering the blade, and also must have some effect on rolling.

Stagnation line
The function of the ridge is to anchor the stagnation line on the paddle face, or at least keep it from wandering too far. Flutter can be interpreted as oscillation of the stagnation line, causing flow to preferentially spill over one side of the blade, then the other, in rapid succession. The resulting pressure fluctuations on the blade cause the paddle to wobble side to side.



A GP held in a canted manner will generally present enough asymmetry to the flow to anchor the stagnation line in the right place, so a canted GP shouldn’t flutter, unless pulled way too hard. An Aleut paddle can be used with the smooth face as the power face in the same way.

It’s the flutter thing.
That’s the purpose of the ridge and it works well to stop any flutter, which can be a problem if you don’t cant a GP.



You should trust the Aleuts and the Inuit on anything with a kayak. They were sophisticated in their technologies for their intended uses, and this wasn’t entertainment to them, it was literally life-saving!

Trust doesn’t work
I do trust the ability of ancient paddlers, but I don’t necessarily trust us to understand what it is they intended. I’m still not convinced the ridge isn’t a cambered back face.



Second, how can you “trust” inconsistent propositions. X and not-X cannot both be true propositions. If a minority of ancient paddle makers made paddles with ridges and a majority made paddles without ridges – both groups depending for their lives on their paddles – which design am I supposed to “trust”. It doesn’t work logically for me.



I’ll await some empirical reports on slicing and rolling with the ridged paddles because there’s more to the sport than a forward stroke.


There’s plenty of info
If you want reports on the behavior of Aleut and GP in various scenarios, you can start reading over at qajaqusa.org, there’s a wealth of info there, most of it very well reasoned and perceptive.



Per your logic argument, there are generally multiple solutions to engineering problems. Neither the GP or the Aleut is a single design — GP and Aleut paddles, with their wide spectrum of sizes, shapes, etc represent a family of solutions to the paddling problem. To pose them as competing designs doesn’t seem particularly useful.



As far as the intentions of the builders in crafting a ridge on a paddle, of course that lies shrouded in mystery. From the standpoint of low-speed fluid mechanics, however, the behavior of the ridge in determining the flow pattern over a paddle is not really an issue of trust, but of analysis and observation.



As far as the effect of the ridge when slicing the blade or rolling, I don’t remember reading anything about a difference between the two. The difference may exist, but I wager it’s subtle, otherwise it would be talked about more often. If it was a real drawback, I bet the Aleut would have discarded the idea — after all, being able to roll successfully is probably more important (as in life-saving) than avoiding flutter.

Someone Handed Me One

– Last Updated: Sep-23-12 5:18 AM EST –

out on the water and I played with it some. The ridged side felt power facey to me. It rolled just like a GP.

I went home thinking it was a GP with an annoying ridge in it... and unnecessarily heavy.

And sometimes
A man’s wife would always cut off the end of a roast before cooking it. When he asked her why she did this, she said that her grandmother was a wonderful cook and that’s what she always did.



The next time he saw his grandmother-in-law, he asked her why she always cut the end off the roast. She said that she always did it because her pan was always too small!



Sometimes things get started for practical reasons and then continue on as “tradition by the experts”.

Research
Carl, I’m initially inclined to disagree with some of the general assertions in your post – re designs not competing, multiple engineering solutions (at least concerning paddles), and stagnation lines – but I agree that I should do more research on Aleut paddles.



I must begin, however, with my more than 60 years of observing paddles. The only ones I have ever seen with an aggressive ridge down the center, other than some of these Aleut paddles, are what I would call Walmart paddles. Cheap things, where the builder merely glued flat blades onto a central pole to produce a $25 paddle.



Preliminary reading of forums indicates much confusion as to the power face of an Aleut, but the consensus seems to be that the ridged face is the primary power face, mainly on the authority of someone named Wolfgang Brinck. Some users report greater stability with the ridged face as the power face; others report less power. At least one poster reports flutter when slicing the Aleut.



Do you think the stagnation line concept – assuming it is relevant to paddles at all – relates more to paddle flutter or paddle power? I think the concept of a stagnation point, or small stagnation area, may be a more relevant concept for the power face of a paddle than a stagnation line. For example, a concave and curved power face would increase and hold the stagnation area more so than a convex power face. This increases power.



It seems conceivable that a sharp and abrupt power face ridge might result in a less laminar and “bumpier” water spillage off the face than a smoother and more flowing dihedral convexity. After all, a paddle is rarely pulled perfectly flush to the water, and hence that edge seems as likely to cause drag and disturbance as it does smoothly parted waters.



Finally, I can’t help but observe that I have paddled with hundreds of canoe and kayak paddles that have no excessive flutter and that none of these has an Aleut ridge. Moreover, no racer in any paddling discipline that I’m aware of uses a paddle with an Aleut ridge. If such a ridge solved any efficiency issue – flutter, power, slippage – why haven’t racers rediscovered that solution?



These are questions I’m asking mainly to myself as I conduct some further research. I’m not confident, however, of finding anything truly objective and empirical. Hardly anyone spends any real money doing real research on canoe or kayak physics. I think you told me that.


The garbage theory of the Aleut ridge
Here’s a theory similar to grandma’s roast.



Once upon a time, many years ago, Aleut paddle makers had a lot of time on their hands. They experimented with lots of sizes, shapes and even goofy appendages. One day, a guy put a ridge down one side of a paddle and declared that it produced some beneficial paddling effect. His buddies tried it out, thought it was worthless, and tossed all his goofy ridge paddles onto the midden mound (garbage heap).



Now guess where archaeologists find most of their ancient stuff – midden mounds.



So some 19th century archeologists discover a few relics of these ridged paddles. They draw pictures of them. They take pictures with their newly invented Kodaks. Because the ridged paddle relics were so mysterious and sexy, the pictures of them proliferated in books out of proportion to their incidence, along with unsubstantiated performance myths.



Finally, some modern paddle makers, seeking distinctive paddle shape niches, and trying ride the late 20th century wave of aboriginal paddling worship, begin to replicate, talk excitedly about and essentially market the ridged paddle.



As the curtain comes down, the goofy garbage of yore is being bling-blinged via the internet as a sacred relic of paddling performance passed down from ancient sages.



Just a theory. Just a theory.


Concept vs actuality
The stagnation line is not a concept, it is a fact of 3-D fluid flow over an object. It marks the boundary between the flow that goes over one side of the object, vs flow that goes over the other side.



A stagnation line exists on a paddle as it must, because some fluid flows around one side, and some flows around the other. A stagnation point only exists in 2-D flow; flow over a paddle is decidedly 3-D. There is no such thing as a stagnation area. Any intro fluids text should suffice to explain the concept in more detail.



Re: the flutter argument, it’s clear to me that the ridge will reduce flutter, based on my experience in experimental fluid mechanics. No one is saying that a ridge is the only, or even the best way of avoiding flutter - that’s your supposition, I think.



The fact that you’ve only seen a ridge on a cheap Euro paddle, and that racers don’t use paddles with a ridge means nothing, of course. It’s an argument, of course, but not proof of anything, as I think you must admit.

Ask a simple question (that was simply
answered) and you get a p.nut pissing contest! Maybe those Greenlanders weren’t skilled enough to put ridges on their paddles.

Concepts are reality
Of course there are stagnation points in 3D flows. Otherwise there couldn’t be a Kutta condition on an airplane wing.



I agree that if you freeze frame a paddle in the water, there will be a spill line, which you can call the stagnation line. But that line will constantly shift along the face of the blade, and may be crooked, as the paddle moves through the water, unless the paddle is pulled perfectly flush to the water at all points along stagnation/spillage line, which seems literally impossible.



Maybe “stagnation point” or “stagnation area” is the wrong term to describe how a cupped paddle “holds” water better than a flat paddle, but there are experiments that show that. The longer the water is “held” before spilling, the more power the blade has.



My experience is mainly with canoe paddles, but I have paddled with dozens of kayak paddles including GP’s. Many paddles do have a mildly raised dihedral line down the center of the blade; others have a more rounded camber. Many argue this helps helps avoid flutter; others say it does so at the penalty of reducing power (the “held” water). Completely contrary, however, is that there are many flat-faced bent shaft canoe racing blades that don’t have any undue flutter.



However, I have never seen any paddle in all my life that has the very high and sharply defined ridge of the Tuktu Aleutian paddle. That’s not meant to be some sort of statement about my paddle knowledge. Rather, it’s supposed to reflect the complete absence of this supposed performance feature in the minds and designs of competitive paddle makers over the last 60 years.

Hey, that feels pretty good
I think that neither the ancient Aleutian islanders nor the Greenlanders had a strong theoretical knowledge of fluid mechanics or access to nice laminar flow test tanks.



They had sticks and carving tools.



And plenty of free time on winter nights.



So they made paddles and tried them.



Eventually they both got to “hey that feels pretty good", and the respective culture’s standard paddle was set.

Chill

– Last Updated: Sep-21-12 6:46 PM EST –

this is getting pretty silly.

Getting way technical
Interesting history, but getting way out there!

Maybe Greenlanders didn’t have any
material to waste.

Re dimensions
Sorry but there is not a stagnation ‘point’ in 3D flow. A cross-section of 3D flow will show a point, but overall on the paddle itself, it is a line. The shifting of the stagnation line you describe is exactly the behavior that causes flutter. I think we’re talking about the same phenomenon, and having a misunderstanding re: terminology, which is understandable for internet discourse. We should really be standing at the blackboard (with a beer?), and all this would be a lot more productive.