Michael Daly wrote: >On 17 Sep 2004 at 9:50, Gary J. MacDonald wrote: > >>I know that runners, for example, can often measure distances within 5% >>or less when they run at particular speeds where their body just clicks >>into rhythm. >I used to keep a training diary when I was a "serious" athlete (XC ski >racing, running and bike racing). Being an engineer, at the end of a year >of keeping the diary, I plotted the data and analysed it. I found that >there was a significant variability - much more than 5%. I also had the >info in the diary on how I felt during the training. Please allow me to >doubt your claim :-) Please doubt! It is in doubting that we learn! What I was thinking of is that when I was a serious runner, I found that if I focused on measuring an unknown path or trail, I could come up with a pretty good measurement most of the time. When possible I checked against maps or surveys, and usually found that I was quite close. Some days I just couldn't do it. I would start out and find that I couldn't maintain the pace. Terrain I could allow for in my time/distance relation, but not the state of my body. The pace I used for measuring was not fast, but some days I just couldn't "do it" with the confidence necessary to measure. GaryJ *************************************************************************** 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 20 Sep 2004 at 10:22, Gary J. MacDonald wrote: > Terrain I could allow for in my > time/distance relation, but not the state of my body. This is the key and is what really stood out to me when I examined my diary data. There was an obvious variability in my performance that wasn't noted in the diary entries - no matter how I _thought_ I did, the actual time vs distance said something else. John W. has commented in the past about the unreliability of using humans to evaluate kayaks/paddles/etc. If I know that I couldn't be consistent on the same bike over the same route when I was highly trained, how could I possibly be objective in evaluating the performance of different kayaks in different conditions today? Clearly, any testing method for this stuff has to be designed to remove the human element or at least reduce the influence of human subjectivity or inconsistency. 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/ ***************************************************************************
-----Original Message----- From: owner-paddlewise_at_paddlewise.net [mailto:owner-paddlewise_at_paddlewise.net] On Behalf Of Michael Daly Subject: Re: [Paddlewise] Testing Clearly, any testing method for this stuff has to be designed to remove the human element or at least reduce the influence of human subjectivity or inconsistency. Mike -----Original Message----- Good science doesn't necessarily require the removal of the human element, especially where it is an important component of the variable your trying to test. Ignoring the diversity of paddling styles strikes me as odd ... for me the motion of the paddle is complex, its also very different with Rasmunsen style racing wing blades, greenland sticks, single bladed canoe paddles, or flat 'euro' blades. Paddles don't paddle themselves, and the paddle is not just for thrust but also for turning and support and feedback about what the whole boat-paddler-paddle system is doing. I can't imagine that it would be easy to replicate the different motions of just one paddler with different blades even approximately by a robot in a tank. Even if you manage to build a half decent robot which can move a paddle in sort of the same way a paddler does, applying power sort of when a paddler does ... how would you test the rather wild assumption that the robotic paddle tank data had any validity when extrapolated to human paddling? Eventually you would have to design an experiment to test the tank data (or a new paddle design derived using it) against real paddler performance for it to have any rigour anyway. DOH! Perhaps for testing paddles an experimental design making appropriate use of replicated performance with samples of paddlers (a methodology common to many rigorous scientific disciplines) might actually be more appropriate than robotic tank testing? But wait, such an experiment exists! ... its called 'competitive sport', and the results are pretty clear .. If you want to go fast in a kayak (sprint, marathon, ww racing) use (feathered) wing paddles, if you want to do a lot of turning and stroke work (slalom, polo) use (feathered) flat 'euro' paddles. No Greenland paddles are seen in competitive sport outside greenland ... and there is a reason for that. I'd wager if wing blades were permitted in the greenlandic races, they would absolutely toast the sticks. If you train with wing paddles and also use greenland paddles this is immediately and blindingly obvious. The paradox is that even though my own experience indicates and the experience of competitive canoe sport proves as a whole which paddles are most efficient and fastest I still prefer greenland paddles mostly, because I just like the feel of them. Test that in a tank or evaluate it in a kayak? Cheers Colin www.kayakscotland.com *************************************************************************** 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 22 Sep 2004 at 9:42, Colin Calder wrote: > Good science doesn't necessarily require the removal of the human > element, especially where it is an important component of the variable > your trying to test. While all your comments are valid in their context, the purpose of the tests proposed is to evaluate the paddles independent of the paddler. If we want a fairly complete understanding of the paddles, we need to study them both independent of the paddler and in the paddler's hands. Since the big debate lately is on the paddle performance characteristics in the water (lift vs drag, efficiency etc) we need to isolate the paddle from the paddler. Once we understand the paddle, then we can look at the paddle in the hands of the paddler. It's like any investigation of physical phenomona. We examine the behavior of the components before the behavior of the composite. Engineers study beams and columns before they study building frames. Wind tunnel tests of wings are done before wind tunnel tests of complete aircraft. Considering how much we know about hulls and humans, it's surprising how little we know about 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/ ***************************************************************************
Mike, I hear what you and JW are saying, but I counter with the argument that reductionism isn't necessarily the most appropriate or only methodology. An analogy: knowing about paddles independent of a paddler might be like knowing about a bat's wing independent of the bat, its not the same problem as knowing about a glider wing independent of the fuselage. We also actually do know a lot about paddles from collective experience. Wing paddles, and greenland paddles in particular only work effectively through specific angles of attack, which change dynamically throughout the catch and stroke. If you fail to replicate that complex motion (be you a tank test dummy or a novice paddler), then they don't do very much very well. If you fail to appreciate this, then the tank tests might not tell you what you think they are telling you - and my argument is the only way to test the validity of an analysis of the fluid dynamics/mechanics of a static paddle in flowing water or a paddle stroked through air and water would be through a comparative methodology (combined or not with an analysis of the bio-energetics) investigating real paddlers proficient in the use of their paddles. Another analogy - Knowing about the fluid dynamics of a disembodied swimmers arm would tell you what? yet small changes in the complex motion of that arm result in great changes in swimming performance. Cheers Colin www.kayakscotland.com <entire previous post removed by moderator> *************************************************************************** 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 23 Sep 2004 at 9:10, Colin Calder wrote: > We also actually do know a lot about paddles from collective > experience. Wing paddles, and greenland paddles in particular only > work effectively through specific angles of attack, which change > dynamically throughout the catch and stroke. If you fail to replicate > that complex motion (be you a tank test dummy or a novice paddler), > then they don't do very much very well. What we know about paddles is largely subjective - well, certainly for GPs and non-racing paddles. I know of many GP users who make very different assessments of their paddles after years of use. There are very different claims about cadence, efficiency etc. In a tank test, we could keep varying the parameters (such as the stroke length and cadence, the angle of attack, etc) and objectively measure the performance. If the person conducting the tests is in any way creative, they will follow a trend to see where it takes them. Aside: There seems to be a tendency among the general public to assume that scientists blindly follow a narrow path and believe everything they see. Having spent a number of years in research (both at university and in the business world), I know this is far from the truth. Given any interesting problem, a good researcher won't want to quit until they've tried everything they can think of - including some really oddball ideas. I can honestly say that the researchers I've known have been among the most creative and imaginative people I've ever met - more so than many of the artists I've known. This is backed by psychological studies that show scientists and engineers think more abstractly than artists; the latter tend to be very concrete thinkers. This is entirely opposite to general perceptions. > my argument is the only way to test the validity of > an analysis of the fluid dynamics/mechanics of a static paddle in > flowing water or a paddle stroked through air and water would be > through a comparative methodology (combined or not with an analysis of > the bio-energetics) investigating real paddlers proficient in the use > of their paddles. Another analogy - Knowing about the fluid dynamics > of a disembodied swimmers arm would tell you what? yet small changes > in the complex motion of that arm result in great changes in swimming > performance. How far apart should the fingers be to maximize the swimmer's power? A test of a disembodied arm can tell you that more accurately than any swimmer could. Once you know that, you can teach the swimmer to use it. Another example is skiers - they get in wind tunnels to measure the resistance of various body positions. This is something that cannot be done without the wind tunnel. No snow, no bumps, no screaming fans - just wind. If we want to really understand the paddles, there are several steps we need to take. One is to analyze the paddle in various flows so we can make some concrete statements about lift vs drag, performance vs angle of attack, steady state vs pulsed/dynamic flow changes and so on. Once we know that, then we can then analyze the way in which the paddle is used by competent paddlers - what is the flow vs time within the stroke. Then we can use the two groups of information to determine whether the paddle is used optimally. Both the tank and the paddler will come into the situation. One without the other is a waste of time. I think that from a point of view of complete understanding, don't jump the first step. However, the origin of this thread (Peter's proposal to estimate efficiency with cheap and dirty tests) is a legitimate step along the way. It won't tell us everything, but it could settle one argument*. Mike * and probably start another :-) *************************************************************************** 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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