Thanks to Peter Chopelas for showing that high aspect ratio paddles are more efficient. Why don't all long distance paddlers use them, particularly if they are nearly twice as efficient? Should the same paddler, paddling over the same distance in comparable conditions, expend nearly half as much energy with a high aspect ratio paddle as with a low aspect ratio paddle? If so, this is such a dramatic difference that high AR paddles should take over for most tourers. But, they don't. Putting it the other way, if a fit paddler was able to input greater energy into paddling with a high AR paddle, shouldn't he or she go faster and last longer than with a low AR paddle? Does anyone have experience of longer distance races where paddlers use both high AR and low AR paddles? Who wins, and who is in best shape at the finish line? If a race is not the best practical test, what is the speed cut-off point where a high AR paddle comes in? The equations seem to suggest that high AR paddles are more efficient at any speed, assuming an equal blade area. Am I paddling up the wrong creek with these questions? Cheers, PT. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Peter, I think there's more physics to it than just being twice as efficient (Although, I'm no expert -- I'm working solely from observation here). The hull speed of the boat, paddler's overall strength, etc, still are huge factors in the equation. This past christmas, I gave my girlfriend a custom Greenland paddle that I built for her. She had paddled for several seasons with a low aspect ratio paddle manufactured for racing, thinking it would improve her speed. She could keep up for half the day, and then was always the last in at the end. The first time she used the Greenland, she kept up with me for 7 miles heading into a 20 knot wind, and has improved her ability to keep up all day dramatically. She now keeps up all day with just about any group when she uses the Greenland. Even though I'm a Greenland paddle enthusiast, I can't say it's all the paddle so much as it is that the paddle is more suited to her ability and strength/stamina. I think the high aspect ratio paddles conserve enough energy to make a difference over a given distance, and that distance is individual to each paddler. I would think a guy like Greg Barton would do as well with any paddle over any distance, but the average mortal will see a difference. In short, the goal is to tailor the propeller to the motor to get the most out of it, in my opinion. Wayne > Should the same paddler, paddling over the same > distance in comparable conditions, expend nearly half as much energy with a > high aspect ratio paddle as with a low aspect ratio paddle? If so, this is > such a dramatic difference that high AR paddles should take over for most > tourers. But, they don't. -------------------------------------------------------------------------- ------ Wayne Smith wsmith16_at_snet.net Check out my sea kayaking & homebrewing page: http://pages.cthome.net/wsmith16/home.html *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Peter Treby Wrote > Thanks to Peter Chopelas for showing that > high aspect ratio paddles are more efficient. > Why don't all long distance paddlers use them, G'Day Peter, Peter and Paddlewise, If you're paddling at sea and with so many shapes and sizes of people and boats, so many idiosyncratic but effective paddling styles and the infinite variety of sea states, is it possible that chaos reigns and there's no fixed answer? For example I choose a short paddle with long blades because: - 1. It maximises my bodies ability to efficiently do work over long distances. 2. Its slippage through the water is forgiving at the end of a long trip when tiredness might make me forget to closely link my upper body and shoulders, so I avoid tendon injury. 3. The long blade and short shaft let me use broken vertical paddle strokes to keep the boat (a Pittarak) moving straight in a following sea. On the other hand if there is going to be a lot of surf involved I'll choose a low aspect ratio paddle because I can roll better with it and my high aspect ratio paddle is not as strong. I'm guessing that many people will have different but equally valid ways of optimising their person/boat/sea efficiency and that physics and biophysics are not the most important issues when at sea. I'll bet a decent bottle of red that they are important for racing on flat water though. All the best, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 10 Jun 2003 at 18:56, Peter Treby wrote: > Thanks to Peter Chopelas for showing that high aspect ratio paddles > are more efficient. As Bob points out, Peter's analysis is based on some assumptions that are not valid and we've argued with him about it several times (this is the third or fourth time he's posted it here or on Baidarka), however, he takes it personally and will not discuss it. Another example of the flaws in it is the horsepower requirements he estimates for a Euro paddler; 0.4hp. I've pointed out that a normal human being is incapable of this level of output. When I suggested a lower value being appropriate, he said _my_ estimate was too high. However, he still hasn't corrected his analysis to reflect what he admits is an unrealistic value. I've said it before and I'll say it again: You cannot prove a physical phenomena with mathematics. You can prove a mathematical concept with mathematics. A mathematical model of a physical process must be demonstrated to be reasonable by experiments and those experiments have not been done by Peter. Hence his "proof" stands as nothing but mathematical fiddling. Another issue is that he will not resolve his definition of efficiency with that of everyone else. Those who have done the experiments know that a _low_ aspect ratio paddle is more efficient (see "The Shape Of The Canoe" by John Winters). Those of us who have paddled with various paddles know from experience that the high aspect ratio paddles tend to be lower in efficiency. As I said in a recent post, when paddling a long day with my Greenland style paddle, my muscles get sore but my joints don't. The lower efficiency means I do more work with less accumulated stress. The basic concept in generating paddling forces efficiently is to move a lot of water at a low velocity. Greenland paddles don't do that and are therefore not as efficient as short, fat Euro paddles. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Peter T. wrote: > Why don't all long distance paddlers use them, particularly if they are > nearly twice as efficient? I think mostly ignorance. As I stated, fluid mechanics is a very complex issue and not intuitive at all, so it is easy to fall victim to the marketing of equally ignorant paddle makers, many who have built reputations making perfectly fine racing or WW paddles (but unsuited to long distance seakayaking). Their experience or knowledge does not translate to the different conditions. Consider how different a sail plane wing is from a fighter wing, different conditions, very different design. Most who PROPERLY learn how to use a high AR native paddle, usually stay with it. But they do feel VERY different, and they are used differently (just like a sail plane vs. a fighter aircraft), so many are not comfortable with a native blade when they try it, and do not want to make the transition. When I first saw a Greenland paddle up close, my reaction was "how can you generate any trust with a skinny stick like that?!". It was years latter that I read a detailed article about a guy who transitioned and found not only less effort and less stress on his body, but also he was cruising at the SAME SPEED with less effort. If forced me to think through the stroke mechanics, and what was actually happening at the blade. It was quite a revelation since it was not obvious even to me, who has many miles in canoes since a child, and now more than a few in kayaks as an adult, and have spent a good part of my professional career doing computational fluid mechanics. Should the same paddler, paddling over the same > distance in comparable conditions, expend nearly half as much energy with a > high aspect ratio paddle as with a low aspect ratio paddle? If so, this is > such a dramatic difference that high AR paddles should take over for most > toreros. But, they don't. Again, ignorance, and fear too. If "looks" odd to most who see what the WW and racers are doing, and since it also feels very different in the hands, most will not given a fair comparison or use the proper criteria in measuring the value of the paddle. Most consumers are greatly influenced by the store sales clerk too. Market acceptance is a very serious concern, no matter how good your product is, if no one will buy it because it "looks funny", you will go broke. I know this from personal experience in more than one industry. > Putting it the other way, if a fit paddler was able to input greater energy > into paddling with a high AR paddle, shouldn't he or she go faster and last > longer than with a low AR paddle? you are confusing terms. NOT faster, or input of greater energy-- you will expend LESS energy over the SAME distance, at the SAME speed, with the higher aspect ratio of otherwise two identical paddles. Or you could go further with a given expenditure of energy, at the same speed (you might notice this if you come to the point of being out of energy before it gets dark). So over the same distance you would have a greater reserve of energy at the end of the day. This is hard to measure in a recreational paddle since most days vary any way. And since almost no paddles are the same in all ways except AR, you would have to specially make them this way to compare them. > Does anyone have experience of longer distance races where paddlers use both > high AR and low AR paddles? Who wins, and who is in best shape at the finish > line? If a race is not the best practical test, what is the speed cut-off > point where a high AR paddle comes in? The equations seem to suggest that > high AR paddles are more efficient at any speed, assuming an equal blade > area. Again you are confusing what I am saying (go back and reread my post). Even a long distance racer is trying to optimize distance over time (i.e. absolute speed). You need to measure energy out put (with perhaps an oxygen uptake mask that measures total volume of air consumed), over a given distance, AT THE SAME SPEED (and yes, any speed, as long as you are comparing the same speed). When you go faster, the hull drag goes up, you must expend more energy to get there in less time, any type of race is not a valid comparison. Even different paddlers will expend energy in different amounts, so you have to measure heart rates, or air consumption, with the same paddler, with the same hull, at the same speed, with different paddles of the same shape, area and weight, with different ARs. I am willing to volunteer to assist with running such comparison tests of as many paddles we can put together for a magazine article or equipment review for anyone that wishes to put together such a comparison. How about it Matt? Anyone at SK mag on the list? > Am I paddling up the wrong creek with these questions? Yes you are, as noted about. IOW, these are the wrong questions, so how can you expect answers that make sense if you, like most people, do not even know what the right questions are? Not your fault, it is just the general lack of understanding of such complex issues as fluid mechanics. Consider that humans have been attempting to build flying machines since the dawn of recorded history, perhaps 3000 years or more, yet it was only about 100 years ago that enough was understood to make the first controlled flight, (and only some 40 years later fly faster than the speed of sound). So the technology required was not obvious, and not intuitive. As an aside, it is interesting to note that the design of the kayak has changed little in perhaps 2000 or more years (except for the materials), and it is still a pretty good design in general for moving long distances in changing and often rough conditions over water by muscle power. A remarkable accomplishment. And why I think often native designs, like the paddles, are superior. Peter C. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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