What is the GP style paddle called

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.

One last 11 dimensional point
Because I don’t think we’ll ever be together at a blackboard and I haven’t drunk a beer since the Reagan administration. Sad as it is, the internet is my only current university.



Forget paddles and paddling.



Is a line not composed of points? If so, then any stagnation line is composed of stagnation points.



Consider an egg. Consider it moving through a fluid. This is a 3D space according to Euclid, or 4D according to Einstein, or 11D according to Witten.



Not considering boundary layer effects, what is the stagnation “geometry” on the frontal end of the egg? I don’t think it’s a line. I suggest, asymptotically, it’s a point.



Back to paddles.



I accept the terminology and actuality of a stagnation line on a paddle face.



Much more reluctantly (without empirical proof), I will accept that a symmetrically spilling stagnation line will reduce paddle flutter vis-a-vis some other stagnation line.



What I have real difficulty accepting is that you can “force” this symmetrical spillage by gluing a ridge on a paddle face. Paddle face movements are too complex and changing in 3D and 4D for the spillage to maintain symmetry. (I don’t believe Witten and his 11D supersymmetry.)



And if I had spilled more many decades ago, I might have finished majoring in physics instead of Budweiser.

I’ve Got it!

– Last Updated: Sep-23-12 6:32 AM EST –

The clever Aleuts put the ridge there for extra weight. The paddle then served double duty as fish bat to finish off their prey.

Eh?

Eh?

Give it to me, paddle brothers. You know I'm right.

Geez!
It’s 6:50 in the morning. I just read this whole thread and now I’m ready for a beer.



The ancients made stuff with the materials they had. It was usually conservative and practical by design. If we have examples to study them someone obviously went through the trouble. There was a reason and as explained, it just works. I have one and have used several others and they do work. Plain and simple. Why spend the energy over analyzing this?

Yes

– Last Updated: Sep-22-12 5:22 PM EST –

Re: the egg, you are correct, in the same way that on a baseball or the nose of a jet, there is a single stagnation point at the front of the body.

On the wing of the jet, however, there will be a stagnation line down the leading edge, and another pinned to the trailing edge (the Kutta condition, as you mentioned). The difference between the two situations is obviously the aspect ratio of the body as it is presented to the flow (AR = weight/height).

An egg, ball or jet nose have AR of 1, more or less, whereas a wing will have an AR that is greater, at least 3 for it to work as intended, 5 or 10 (or more) leads to increased aerodynamic efficiency.

Anyway, the high AR forces the fluid to pick a side as it flows around the wing - the shape drives the flow. Some flow will sneak around the end of a finite wing, creating the tip vortex, but for the majority of the length, the wing separates the flow into two distinct streams.

An egg presents a fairly uniform obstacle, so the flow is free to move around it on all sides. Flow behind the body depends on its shape - an egg or baseball will have a wide wake zone, generally turbulent (bluff-body wake), a streamlined jet will have a stagnation point at the end somewhere.

A GP is a high AR body, so I was thinking of that when I misspoke in my previous post. I said 'there is no stagnation point in 3D flow' and should have finished with 'around a high aspect ratio body' to make it a correct statement.

PS a ridge anchors the stagnation line, but does not necessary make the flow symmetrical - a canted blade will not have symmetrical flow. A wandering stag. line causes flutter via pressure fluctuations; the ridge stops the wandering.

I know, I know…
I hear you and get your point. But my field is fluid mechanics, and there is no such thing as ‘over-analyzing’ an issue like this, it’s what I do. I certainly understand those who want to ignore all the technical talk - many (most?) of my students feel the same way.

then
you must also factor in that the paddle doesn’t just come straight back, it is also piercing or traveling out from the kayak. this would relieve the tip from a vortex that is caused from shedding the flow…the actual water shedding will be away from the tip.



{just feeding the fire}



Best Wishes

Roy

Engineers and over analyzing…
I’ve got a few Engineers as friends and they drive me crazy. No worries since I’m used to it. ;-]

Quaqte from an old manager:
“There comes a time in the life of every project when you need to shoot the engineer and move on.”

Engineer’s Motto:
If it ain’t broke

it doesn’t have enough added features

call it whatever you want.
I don’t care. There is a difference betw. greenland and Aleutian paddles, and a wide variation within both types.

Aleutian paddles

– Last Updated: Sep-23-12 12:06 PM EST –

I'm very late to this discussion as I was doing long overdue house cleaning instead of looking at paddling.net.

I made a Baidarka at the Skinboat School in 2003. I test paddled a number of different size Biadarkas in the bay to determine what size I should build. During those trials I used an Aleutian paddle. After those trials, I told Corey that it would take me a while to become comfortable in narrow Baidarks (the one I built is 19" at the water line with substantial flare above) but I absolutely wanted one of those paddles; I found it that impressive! I had only read about Aleutian paddles, and never seen or tried one before. The paddle I made at the Skinboat School in 03' has been the paddle I have used for 95% of my paddling in the nine years since. The rest of the time I use a GP.

Anyone can formulate a argument for anything and it frequently is done on internet forums: you argue "A" and I therefore argue "B". The question of which face is the power face on a Aleutian paddle is a case in point. My opinion is below.

When viewed from the side (with flat side down), an Aleutian paddle has a taper. The taper starts on the ridge side at loom and runs down to near the bottom (side view) of the nearly flat bottom side. The taper is the thickness of the loom minus the thickness of the paddle tip. This taper means the paddle is partially ahead of the hands in use (ridge facing paddler), promoting stability from this orientation as well as from the ridge. If used with the ridge side forward, the same taper would place the paddle partially behind the hands, promoting flutter if used in this orientation.

I was told this is how to hold the Aleutian paddle and now believe it from my 9 year experience paddling with an Aleutian paddle. This "theory" further was tested in late May when a powerboat wake threw my full weight onto an Aleutian paddle just as I was bracing while getting out of my kayak. That paddle, constructed to Renzo Beltrane's plans, is less stout than the bombproof Skinboat School paddles (with a sitka spruce core). The paddle cracked lengthwise on the power face. The crack starting on the surface nearer to the tip, becoming deep under the ridge as it approached the loom. There was no spare paddle among the 20 or so on the trip-lesson was taught. To get back to to the launch site, I had to paddle with the flat face rearward (backwards) to have water pressure close the crack as I paddled. The crack would have opened and maybe the paddle broken if I had paddling with the ridge rearward, considering the bad crack. When I reached the launch site after paddling holding the paddle backwards, my forearms hurt. I attribute this to resisting the tendency of the paddle to flutter when used the wrong orientation. The crack has been repaired with two types of epoxy and is holding up to use. I'm going to carve another paddle to the same plans with a Sitka core for greater strength.

I am not a engineer or trained physicist and do not want to get into discussions about water flow around different shapes; I would be in over my head in such discussions. What I'm offering is my 9 year experience with the Skinboat School Aleutian and two years with the Beltraine Aleutian (he attributes his design to a paddle in the Smithsonian).

Dave

Don’t pick on engineers. Other thoughts.

– Last Updated: Sep-23-12 4:45 PM EST –

I'm not an engineer, yet I'm absolutely positive I can bore a forum with over analysis.

BTW, Carldelo, are you in NYC? Why did I think you were in CA?

I'm glad Ret-Dave entered the thread because I saw Aleut posts by him in old threads I researched, and I'm especially glad he mentioned the offset nature of the Aleut blade with respect to the shaft. I'm not sure anyone has mentioned that the Aleut seems to have a pointed tip rather than a flattish GP tip.

I think four things contribute to the perceived stability (non-flutter) when using the ridged side as the power face.

1. The ridge anchors the stagnation line, according to Carl. I only buy this when the paddle face is pulled flush to the water. If the paddle face is rotated around or translated along the X, Y or Z axes during a stroke -- sliced, pitched, angled, canted -- I think this ridge will cause unpredictable water flows that could even cause flutter. So, I assume an Aleut paddler learns to pull during a power stroke in such a manner as to maximize the stabilization potential of the ridge.

2. When a paddle face is offset from the shaft, the indented face will produce less flutter as power face than the flush face will. I know this because I have a straight shaft ZRE paddle with an offset blade with otherwise identical faces, which exhibits this exact phenomenon. Therefore, the blade offset on the Aleut may be contributing as much or more to the stability as the ridge.

3. This is speculation, but the pointy paddle end may cause less flutter upon entry than a flattish end. Many aboriginal and native canoe paddles today, for example, have pointed ends.

4. Subjective superstition and hooey. It seems obvious to me that non-fluttering canoe, Euro and GP paddles can be made without Aleut ridges, because they are all over the paddling world. The Aleut shape is the outlier. (Actually, I think all paddles flutter a little at some velocities, but the flutter can easily be controlled by grip.) Therefore, while Aleut paddlers can love their ridged paddles for all sorts of functional, aesthetic and historical reasons, I'm not convinced that these paddles offer any better stability or other efficiencies than many good non-ridged paddle designs do.

There -- I proved my opening sentence.

Thanks Dave
I did a fairly leisurely paddle of five miles in an hour with your Aleut paddle. Ridge pointing back.



I don’t know why I like it better that way but I do…so you internet engineers can keep splaining…



I missed todays addenda. What a beautiful day to paddle.

reflections on Glen’s post
Re. the attributes in Glen’s point 1 and point 2— I see no reason to separate them and think they act together synergistically. That’s my opinion, not based on any experiments.



Point 3 is interesting. The Skinboat School paddle comes to a slightly rounded point. The Beltraine paddle ends in a almost flat tip. I looked at George Dyson’s 1986 book “Baidarka”, to see what it shows. In the historical painting and drawings from the 1700’s and 1800’s there are paddles tips covering the whole range from rounded to very pointed. Almost half of the illustrations show single blades being used in the Baidarkas and larger skin boats. No Freestyle moves are shown.



Re. point 4, I will just state that Aleutian paddles work for me and I don’t really need to know the official or generally accepted reason why they do.



Since we both live in Ct, a small state, we should meet at a lake such as Bantam Lake and trade paddles back and forth on a long paddle. When pondering the advantages of sharp edge GP vs. more rounded edges, I found the best method was to paddle a few hours with a friend and exchange paddles every 15-20 minutes. All 15 people I’ve done that with ended up favoring the sharp edge paddle. I started using a rounded edge GP and was surprised myself when I also favored the sharp edge GP. Live and learn.



Dave

The ridge is on my paddle to be and
it ain’t coming off.

Skinboat School. Bantam. Canoe.
Dave, where is the Skinboat School you keep mentioning? I visited a place up around Anacortes Island in 1999 or 2000, where a guy had a school to build baidarkas. I got all interested and bought Dyson’s book. Almost bought a baidarka at the Wilton Outdoor Center.



Sure, I’d love to try the paddle if I can clean all the protected mammals out of my neglected kayaks.



Since I’ve only been canoeing for the last several years, I really need an Aleut-ified single blade paddle. But I don’t have the interest or skill to build one.

So yesterday…
I set out to make an effort to try the non-ridged face of my Aleut paddle as the power face.



First I tried just paddling. It flutters.



Next I tried various canted orientations. I found that I could make it not flutter with some cant and a slow, low-angle stroke. But if I tried to increase the power of the canted stroke the paddle started to climb to the surface. I really couldn’t find a comfortable for me angle.



I tried chanting. Unfortunately I don’t know any Greenlandish chants, so I did a Welsh one that my grandmother taught me. I found it ineffective.



My hands were wet at this point, so I couldn’t get the incense lit to do any incantations.



So I went back to using the ridge face as the power face. low-angle, high-angle, slow cadence, faster cadence, high-power, low-power. It just works. It just feels right to me.



So for me, with the Aleut paddle that I made this spring, ridge face is power face.

wrong language used

– Last Updated: Sep-24-12 12:38 PM EST –

Mintjulep,

Aleutian paddles came from the Pacific North West, so Welch or Greenlandic chants would be unlikely to work even if the gods of Aleutian paddles were listening.

My 9 year experience with the Aleutian paddle and my understanding of the effects of the slant built into the paddle faces concur with your opinion that ridge face is power face.

Dave

Skinboat School
Glen,



I’ve been mentioning the Skinboat School only to identify the pattern of the Aleut paddle I’ve most used. It’s likely based on some historical paddle, I haven’t asked which. Looking at the few patterns online, Zimmerly’s looks most like the one I carved.



It is the same place you visited on Anacortes Island, WA., owned by Corey Freedman. I saw one of his early Baidarka frames (no skin) on the dock at the Center For Wooden Boats around 1993. I couldn’t get it out of my mind, so I went to the Skinboat School and built one a decade later. I also also carved an Aleutian paddle while there, which has been my favorite since. I’ve made 4 others to the same pattern, and two to Beltrane’s pattern.



No need to clear out spiders from your kayaks. I could bring two kayaks; the Baidarka and another, or a kayak and the Rapidfire. Contact me by email and we can set a date for a Bantam Lake paddle exploration. I’ll bring the two different pattern Aleutian paddles (and a spare).



Dave