It looks like you're new here. If you want to get involved, click one of these buttons!
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.
this is getting pretty silly.
The clever Aleuts put the ridge there for extra weight. The paddle then served double duty as fish bat to finish off their prey.
Give it to me, paddle brothers. You know I'm right.
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'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).
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.
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.