The formulas are great and the testimonials about which paddle is most efficient etc. is always exciting. The freewheeling nature of these periodic debates, with attendant certainty regarding absolute correctness of positions of respective authors is encouraged by the total lack of data from tests on the water that quantitate the "WORK" being done with one or another paddle in the hands of one or more paddlers in one or more paddling environments. No data = No meaningful conclusions! Formulas are not "DATA". I look forward to citations of published data quantitating actual "WORK" in one condition or another and paddle vs paddle. Thanks, Chuck Sutherland *************************************************************************** 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/ ***************************************************************************
not qualified in any way to weigh in on the physics of paddling but... I think we need to have someone put together an "Iron Byron" for paddling. The US Golf Association has a unit for consistently testing golf equipment with a standard swing (http://www.leaderboard.com/GLOSSARY_IRONBYRON). I'm sure something like this would be quite inexpensive to build ;o)...I'm certain we'd need some sponsors!! C'mon all you garage inventors...let's see your best mechanical paddler to test these paddles!! And as a bonus, what a great stoker to have in the back of your double on those long stretches into the wind. Of course, unless it is a solar powered unit you've got some power issues. K *************************************************************************** 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/ ***************************************************************************
I think the optimum paddle is only optimum for a particular paddler, using it for a particular set of circumstances. In both canoeing and kayaking, I started with a paddle too long and too heavy for me to paddle most efficiently. If a paddle is too long and/or too heavy, a person's stroke rate may be too slow to maintain speed in their particular boat. Thus each stroke feels more like the first one when the boat is being accelerated. The preferred shape of the blade is also a function of the paddler's style and preference for speed, long paddles with the least effect on the body, or boat control. I'm 5'2" and need a narrow boat to be confortable paddling over it's sides. I like to keep my paddle close to the boat to prevent the sweeping back and forth that happens in response to a low, partially sweep stroke. I found that when I manintain a kayak or canoe at it's best cruising speed, I am mostly feeling like I'm stirring water. I've also found that differently shaped paddles behave differently in the water and I now pick ones that feel good when paddled in my own paddling style. I currently use mid-Swift paddles. This paddle has enough support for bracing while not being too big for me to be able to give it the quick move through it's forward motion part of the paddle stroke. The spoon allows for a very quick and solid plant so the initial part of the stroke is very fast. But... it is grabby at the end of the stroke and must be allowed to drift back alongside the boat before being taken out of the water so my speed could be improved by changing to a different shape, probably a modified wing. But I currently paddle faster than most people I paddle with so I don't need a faster paddle unless I take up racing. I have had physics courses and taught high school physics and I am sure that while a manufacturer wants to know how to make his paddles optimal, the definition of what is optimal is very much subjective. Each of us develops paddling strokes based on our body types, training and equipment. I have used paddles that fluttered and found that I could change the angle of attack and have them work better. But formulas for how a paddle works in a test situation don't have enough impact on real life paddling to matter except when comparing bottom and top end paddles. If you are a big guy and like to apply a lot of force, get a paddle with a big blade. But if you are short, female, don't have a lot of boddy strength, get a very small blade. You will be able to paddle just as fast as the big guys if you have the right sized paddle for you and learn the correct paddling techniques, using your stomach and leg muscles to paddle forward, and your arms to lift and push the paddle. The biggest variable in paddling is technique. The second biggest one is size and, strength, and stamina of the paddlers. Then comes boat design, and finally paddling design. So you really first have to learn how to perform a really efficient forward stroke as well as the other strokes you need for the places you paddle, then find the paddle that works best with your technique and boat. Weaker people need to paddle with a high stroke rate and less attack, while the big guys can continue to use their big paddles with a slower stroke rate. The trick is to be sure you are using a paddle and techinque and stroke rate so your boat doesn't slow down between strokes. That way, you take inertia out of the picture and get to travel in high gear all the time. This results in the least output from your body for the maximum forward motion. Remember that work, after all is just force X distance. So if we have exerted a lower force (our energy on the paddle) over a long distance (the 14 inches or so of the forward part of the stroke (times the stroke numbers) both paddlers come out the same but the one using the least force on the smallest mass does less bad stuff to the body. The equipment we started out with rapidly becomes obselete as we gain new skills and find our preferred paddling envrionment and styles. We adapt to out equipment and then find it will no longer do what we want it to do as we gain new skills. Since I haven't reached perfection in my paddling skills, I expect I may need different equipment in the future. I've already changed my kayak from a Eddyline Raven to a Mayan Seas Performa so I could master higher level skills. (The Eddyline is too wide and has too much volume for be to be able to do higher level paddling in it.) So the best way to judge a paddle is to just try it out under the conditions you wish to use it. The second best would be descriptions of how if feels to you, under the described circumstances you use it. You also have to tell us about your size, including torso hight and width of shoulders, strength, paddling skills, attack angle, paddling circumstances such as flat water or big waves,etc. Then we could judge if the paddle might work for us and at least build a list of paddles we might like. The least informative information is the numbers generated by unscientific (uncontrolled variables) measurements. However, if each paddle was attached to a robot paddler at different attack levels and forces, etc. we could probably generate some measurements that we could use to make decisions as to the best paddles for our selves. *************************************************************************** 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. 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On 11 Jun 2003 at 11:45, skimmer_at_mail3.enter.net wrote: > I look forward to citations of published data quantitating actual > "WORK" in one condition or another and paddle vs paddle. Some of us have been pointing to published material of some sort or another as a minimal check on the equations that one or another person posts. Certainly, I refer to John Winters' published data on paddles in "The Shape Of The Canoe" - in particular the results of lab tests that show the increase in efficiency with the reduction of aspect ratio. As well, Nick and Kirk have pointed us to web sites and other sources that identify various paddle characteristics. I agree, though, what we need is a comprehensive source of paddle physics and hydrodynamics backed with lab data. AFAIK, this doesn't yet exist. Some very ambitious soul has to go thru the mountains of publications and accumulate and summarize the info that's out there. Volunteers?? :-) 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/ ***************************************************************************
Although there is no question in my mind as to the outcome, the way to prove this is not through mathematics, but through measurements. By measuring the force x distance applied to different paddles when propelling a particular boat at a particular speed, one could answer the question definitively. Unfortunately, the instrumentation required for that would be fairly complex, and may inhibit normal use of the paddles. Another way of measuring it is through oxygen uptake of the paddler under controlled conditions (same paddler, same boat, and same speed). That would factor in not only the work applied to the paddle, but any secondary/ergonomic effects on the paddler. I think the instrumentation is simpler, and it takes all effects into account. Is anyone on the list familiar with current techniques for measuring oxygen uptake? Steve Brown I agree, though, what we need is a comprehensive source of paddle physics and hydrodynamics backed with lab data. AFAIK, this doesn't yet exist. Some very ambitious soul has to go thru the mountains of publications and accumulate and summarize the info that's out there. Volunteers?? :-) 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/ ***************************************************************************
At 12:16 p.m. 11/06/03 -0700, Steve Brown wrote: >Although there is no question in my mind as to the outcome, the way to >prove this is not through mathematics, but through measurements. >By measuring the force x distance applied to different paddles when >propelling a particular boat at a particular speed, one could answer the >question definitively. Unfortunately, the instrumentation required for >that would be fairly complex, and may inhibit normal use of the paddles. Gaining knowledge can be achieved through different means and one good approach that will give quantitative results, to be interpreted later by theory would be the STATISTICAL APPROACH. Since this is such a difficult subject, and is repeating itself without new input, it is possible to suggest that... 10 or 20 paddlers get together with the different paddles at hand, giving each one the paddle that has the length he usually uses. Randomly give them different paddles, time their round trip, allow them to rest in between trials, give some factor of doubt to the fact that at their last trial they may be more tired than in the first. (This can be done by having him paddle with the same paddle twice at the first half of his trial and at the second half and average the result). Plot the results and get a value for the best paddles and work out an explanation from there. Weather conditions will have to stay more or less similar, or if they change the sampling must be increased to more paddlers or different days. Some paddlers will be faster always and some others slower always, so some inferences on paddling style associated with paddle shape could be also obtained. A kayaking club with good number of regular assistants could do the test and would lead to invaluable information. After that two things can be done. 1.- Give the plots to theoreticians to work a model. 2.- Have the plots ready for the next time this issue is questioned in this list. Best Regards, Rafael www.mayanseas.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 11 Jun 2003 at 12:16, Steve Brown wrote: > Although there is no question in my mind as to the outcome, the way to > prove this is not through mathematics, but through measurements. The lab data I was referring to is measurements. > measuring the force x distance applied to different paddles when > propelling a particular boat at a particular speed, one could answer > the question definitively. Unfortunately, the instrumentation required > for that would be fairly complex, and may inhibit normal use of the > paddles. [...] > instrumentation is simpler, and it takes all effects into account. Is > anyone on the list familiar with current techniques for measuring > oxygen uptake? I think it would be easier to instrument the paddle and get realistic measures than to do O2 uptake measurements. Unless the equipment for doing O2 uptake a shrunk considerably in the past couple of decades, the test for it would require a paddler in a fixed kayak. This would not be as realistic as a moving kayak. I bet that the sports research journals already have such data published for competitive paddlers in some form or other. Another problem with introducing a paddler to the test is that the paddler's performance variations may be greater than the paddle variations. That's what make an Iron Byron better. OTOH, slapping strain guages all over a paddle and calibrating it would be easier, since you could read the guages in real time with a laptop computer in a waterproof case (well, a few other bits as well...). Another option - Kirk (IIRC) once sent me a reference to a pressure-sensitive fabric that he hypothesized could be adapted to covering a paddle blade and measuring pressure distributions in real time. Measuring the paddle directly means that the paddler's performance is less significant and the Iron Byron approach is less important. The last time I slapped strain guages all over something and did tests, the computer available filled a room the size of a one-car garage, had 32k of memory (and a 5MB disk drive the size of a washing machine) and had less ooomph than the watch I now have on my wrist. Either way, the solution requires $$$. That's why noodling on the back of an envelope suffices for now. :-) 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/ ***************************************************************************
On Wed, 11 Jun 2003 16:16:11 -0400, "Michael Daly" <michaeldaly_at_rogers.com> said: > Another option - Kirk (IIRC) once sent me a reference to a > pressure-sensitive fabric that he hypothesized could be adapted to > covering a paddle blade and measuring pressure distributions in real > time. Measuring the paddle directly means that the paddler's > performance is less significant and the Iron Byron approach is less > important. Using the pressure sensitive fabric to wire a paddle was the idea of one of the inventors of the pressure sensitive fabric. To the best of my knowledge he's never gotten around to actually wiring a paddle. At the time he said the only hardware he would need was a laptop with some commmonly available lab recording software on it. There's an older writeup about the material online: http://csmweb2.emcweb.com/durable/1999/11/04/p13s1.htm Hunting around a little, pressure sensitive paint for determining pressure points in aerodynamic testing is currently "available", http://innssi.com/psp/index_applications_low_speed.htm . The pressure sensitive paint is not available commercially, formulations are available on "request", yeah, that sounds like it would be in my budget... Kirk -- Kirk Olsen kork4_at_cluemail.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/ ***************************************************************************
Rafael wrote: - > one good approach that will give quantitative > results, to be interpreted later by theory > would be the STATISTICAL APPROACH. G'day, Makes some sense to me. Instrumenting a paddle is expensive in time and money, especially if you include the very best subminiature gyroscopes so that velocity can be approximately determined. Trying to derive velocity from a strain gauge measurement in a paddle requires difficult assumptions and I'm told gives very poor signal to noise. A statistical approach might be cheaper if the null hypothesis was kept simple and the sample number very high. For example would anyone be interested in joining an experiment by email to test the relationship between blade 'aspect ratio' and speed of paddling? This would need roughly 100 volunteers to measure the long and short axes of their blades then paddle a fixed distance and measure their speed. The paddling would need to be under a simple set of conditions TBD. This could be at the paddlers convenience, in their own location and in their own time. All measurements to be provided back channel and privacy to be respected. ie results published make no reference to particular paddlers and the source of data would be erased. The number of paddlers required could be reduced if the paddling conditions were made stringent, but this might be impractical. It wouldn't produce conclusive proof and doesn't have the virtue of a double blind study. However, it may give an indication of a trend and if there were significant results they would be relevant across a diverse range of paddlers and boats. If enough people are interested I'll coordinate the effort, get the results professionally analysed and publish them on this list. Any comments? Any interest? 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/ ***************************************************************************
Some comments on statistical approach....not being a statistician nor ever playing one on TV.... This would be an interesting endeavor (and I'd love to see the results and I'd certainly be willing to participate) but it strikes me that the amount of variation due to 'other' sources (conditions, boat/hull design, stroke mechanics, paddler skill/condition/mood that day, etc) would likely swamp out any detectable variation due to paddle. No good way to control those other sources of variation - and they are going to be HUGE relative to the paddle variation (for instance, I'm sure there have been lengthy exchanges about hull designs in the past and my guess is hull design would affect these times much more than paddle). I suppose it is a bit like testing tires by having them run on 100 different cars....with no control on make...1 pickup, 1 Porsche, 1 Chevy Vega, 1 Ford Pinto, 1 Ferrari, etc I've seen guys that could likely blow my doors off paddling with only a Q-tip...wouldn't matter what paddle you gave me...unless it had "Honda 7.5 hp" stamped on the side.... ;o) Just my 2 cents - FWIW, K PS: Just thinking out loud but maybe one way to somewhat capture this would be to have each paddler use some standard, widely available paddle, then also do this with their own, and use a difference in times as some measure - and run a couple of trials each - two days, each day do one run with standard paddle first, then vice versa. Not sure this would adequately capture any/enough of that 'other' variation - but it might. Of course, you have to find a standard paddle that everyone can get their hands on....probably no small task. *************************************************************************** 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/ ***************************************************************************
Keith wrote: - > it strikes me that the amount of variation > due to 'other' sources (conditions, boat/hull > design, stroke mechanics, paddler skill/condition > /mood that day, etc) would likely swamp out any > detectable variation due to paddle. ---------- > --------- PS: Just thinking out loud but maybe > one way to somewhat capture this would be to have > each paddler use some standard, widely available paddle, G'Day Keith, Thanks for both the encouragement and the critique, thats exactly what is needed to think such an endeavour through. I take your point about the large number of uncontrolled variables. It may be a forlorn hope that the large number of variables can be coped with by using a sufficiently high sample, it is after all a law of diminishing returns. The use of a standard paddle as a reference by each paddler would be ideal, but not easy to achieve. A less rigorous but more practical alternative might be for each paddler to use two paddles with different 'aspect ratios' and build a comparison of the two into the analysis. What do you think? 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/ ***************************************************************************
In terms of high sample size - my guess is that due to the relatively small variation due to paddle versus the relatively huge variation due to the other factors, you'd have a tough time finding enough paddlers to cure this by sample size. Just a hunch. Worked a bit with ecological/environmental data and it too is very 'noisy' - even with monstrous sample sizes. The idea of having each paddler test two paddles and using a difference stat might have merit - I'm not sure. There are probably some underlying assumptions that may/may not be valid - things like the relationship between aspect ratio and performance being a constant relationship across the whole range of values - is it linear? curvilinear? Does this change for each paddler for some unknown reason? People testing different portions of the range might be problematic - some might test two very similar paddles (and those may be high or low in the range), others two very different paddles with regards to aspect ratio. At any rate, it might solve part of the problem but it might introduce 'noise' of a different type. I suppose the original suggestion to use a standard paddle contains some of these same ills. K *************************************************************************** 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/ ***************************************************************************
>The idea of having each paddler test two paddles and using a difference >stat might have merit - I'm not sure. There are probably some underlying >assumptions that may/may not be valid - things like the relationship >between aspect ratio and performance being a constant relationship across >the whole range of values - is it linear? curvilinear? Does this change >for each paddler for some unknown reason? People testing different >portions of the range might be problematic - some might test two very >similar paddles (and those may be high or low in the range), others two >very different paddles with regards to aspect ratio. At any rate, it >might solve part of the problem but it might introduce 'noise' of a >different type. I suppose the original suggestion to use a standard >paddle contains some of these same ills. I come back to my original suggestion. The most controlled situation is asking members of a local club to try, at their convenient time 3 or 4 paddle models. You only need to get one model of each paddle and give it to them and they will time their effort with them and report the relative results. That will cancel boat type, etc. 20 paddlers reporting good tests should give a good relative behavior, which would have to be normalized somehow in order to be able to plot all the results in one chart. A better placer to do this test would be where there is some kind of Olympic track or good quiet lake. Best Regards, Rafael el cayucochief www.mayanseas.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/ ***************************************************************************
This might be a good project for one or more kayak symposiums, where you have a lot of kayaking enthusiasts and paddles, boats, etc., can be better controlled. Chuck Holst *************************************************************************** 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/ ***************************************************************************
G'Day, Thanks for all the responses - forgive me if I don't reply individually today as I'm about to go on a trip. I appreciate the issues raised and will try to address them concisely though none of my answers are mean't to be strong points of view. Using a fixed set of paddles reduces one set of variables but introduces others. For example the variability associated with learning to use an unfamiliar paddle. Until the measurements are analysed we don't know which would have more effect on data noise. Both approaches could have advantages. The use of a variety of paddles may have some advantages - a non linear relationship between 'aspect ratio' and speed might improve the 'signal to noise'. For example if a significant effect is more evident at an extreme value you have a chance of seeing it. Using a fixed set of paddles doesn't give you this opportunity. It could be interesting to carry out tests at one or more symposia. Theres a large club meeting in November over here. It could also be worthwhile to carry out tests via email. No reason not to do both. Regarding testing on flat water. I agree, though its necessary to decide what is flat (less than 0.5m waves?). It would also be necessary to select water without current or organise the tests so paddling is downstream then upstream and average the results. Regarding Olympic racing tests - I expect they have been done but have they been done across the population of paddlers - and can such results be extrapolated to the general population of paddlers trying to paddle efficiently? If the effect of paddle aspect ratio could be swamped by noise across the general population of paddlers does it mean it is not an important effect except for racers? Of course we don't actually know that the effect would be swamped by noise. I really appreciate comments and will start to build them into a protocol to present in early July. 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/ ***************************************************************************
PeterO wrote: >>>>>Instrumenting a paddle is expensive in time and money, especially if you include the very best subminiature gyroscopes so that velocity can be approximately determined. Trying to derive velocity from a strain gauge measurement in a paddle requires difficult assumptions and I'm told gives very poor signal to noise.<<<<< Others wrote similar things as well. I looked into making a paddle outfitted with strain gauges and even rotational measuring devices to assure a consistent stroke for comparison purposes about 18 years ago when Sea Kayaker magazine first wanted to compare the drag on kayaks. At that time I was advised by a friend who was an electrical engineer and the inventor of many scientific instruments for university researchers, that two strain gauges at ninety degrees to each other that were sampled several time during each stroke could provide the all data needed (if the stroke was consistent--why I also was looking into the rotation in space measuring gauges). At the time the data from the strain gauges could be run through an analog/digital converter and into a small Radio Shack laptop computer along with the data from an knotmeter at the same time. The main problem was the rotational measuring devices available were too slow (slew rate?), too heavy, and too expensive (at that time). I imagine that situation may have changed. Sea Kayaker rented time at a ship model testing facility and lost interest in other methods of physically comparing drag on kayaks. Much later analog/digital/computer devices to store the data became plentiful, more powerful, smaller and cheaper. If you used the same paddler for the tests you could probably eliminate the need for rotational measuring devices (as the experts stroke would probably remain fairly consistent especially if only the kayak was varied). I have proposed that some engineer type try this several times now on this list and in other places (including to Greg Barton for consideration by the US Team). Greg is an engineer and a paddle maker. What a perfect combination for this. Unfortunately, he is also probably, like me, too busy at this time (right now this is too low a priority for me although it is something I'd eventually like to try out if no one else does it first). I think someone who came up with an electronic paddle shaft (that blades could be changed on) could sell such a system to several groups of people. People who want to compare paddle blades. People who want to compare boats. People who want to compare paddlers and train them to be better paddlers. People who just want the latest technology to play with. It seems to me that such a tool could be made to sell for well under $1000 dollars. I think measuring the strain on the shaft is superior to measuring the pressure on the blades (another approach I looked into 18 years ago) because it wouldn't allow interchangeable blades and at the time looked to be harder to build. A paddle with the pressure sensitive fabric (or paint) might still make a good way to compare kayaks and paddlers though. Strain gauges on a shaft could be easily calibrated with weights and checked periodically with weights to assure consistency over time. If any one wants to try an approach like this I'll try to do what I can to help them. Matt Broze www.marinerkayaks.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/ ***************************************************************************
Matt wrote > I looked into making a paddle outfitted > with strain gauges and even rotational > measuring devices to assure a consistent > stroke for comparison purposes G'day Matt and Paddlewise, I agree with your assessments and design strategy completely. Only difference is I'm thinking about a tool for the "Average Paddler"/Paddle combination rather than for assessing the paddle in the hands of an expert with a fixed style. Hence, as you point out, the need for rotational measuring devices (or gyroscopes). I checked out costs, size and response rates of gyroscopes last year. They were still too slow, but amazingly small and expensive. Quantifying the average paddler may be a pipe dream, with expert observation combined with good knowledge of paddle characteristics being more practical. Why the pipe dream? The motivation is to reduce injury by providing accurate and individual feedback to sports physio's advising your average paddler on style and equipment. Imagine what a sports store could do with such a facility. Every kayak shop and gym should have one!!!!!! All the best, PeterO (Whos off to Ohio, then the Big Apple and hopes to meet Ralph and paddle with the Boathouse Club) *************************************************************************** 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/ ***************************************************************************
Accelerometers (either single or multi-axis) may be a better choice for instrumenting a paddle. No spin-up and resulting power requirements and less obtrusive though probably still problematic. Dave G. Poquoson, Va. *************************************************************************** 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/ ***************************************************************************
My first reaction to the idea of strain gauges is that they would only measure force and thus would not be a good means of measuring paddle efficiency. The whole problem with figuring out paddle efficiency is trying to relate a force applied to work done to the kayak or power received from the paddle. I do not think you can determine this by measuring force alone. I think you need to be able to determine speed of the paddle and this would then need to be adjusted for speed of the boat and then combine it with force measurements. I think the strain gauges could be used to analyze boat efficiency, but I'm not sure that they could be used to analyze paddles effectively. On Friday, June 13, 2003, at 12:30 AM, Matt Broze wrote: > PeterO wrote: >> Instrumenting a paddle is expensive in time and money, especially if >> you >> include the very best subminiature gyroscopes so that velocity can be >> approximately determined. Trying to derive velocity from a strain >> gauge >> measurement in a paddle requires difficult assumptions and I'm told >> gives >> very poor signal to noise.<<<<< > Others wrote similar things as well. > > I looked into making a paddle outfitted with strain gauges and even > rotational measuring devices to assure a consistent stroke for > comparison > purposes about 18 years ago when Sea Kayaker magazine first wanted to > compare the drag on kayaks. <snip> > <snip> Strain gauges on a shaft could be > easily calibrated with weights and checked periodically with weights to > assure consistency over time. If any one wants to try an approach like > this > I'll try to do what I can to help them. > Nick Schade Guillemot Kayaks 824 Thompson St Glastonbury, CT t> 3 USA Ph/Fx: (860) 659-8847 http://www.guillemot-kayaks.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 12 Jun 2003 at 21:30, Matt Broze wrote: > first). I think someone who came up with an electronic paddle shaft > (that blades could be changed on) could sell such a system to several > groups of people. Lendal's Paddlok system comes to mind, though you'd have to modify other maker's blades to fit. If you get a variable length version, then the widgets you plug into other makers' blades to adapt to the Lendal shaft could be accomodated. You'd have to fabricate your own adapter widgets, of course - no one sells such a thing that I'm aware of. Paddle rotation may be measured, but gyros aren't the way to go. Accelerometers only measure acceleration, not velocity, so any constant velocity period in the stroke would be unknown (except in duration). You might be able to make it work (integration of values etc) but I'd have to think about it. There were MIDI based systems that allowed people to "conduct" music by following thier hands (without touching anything) - something like that could be adapted. On Nick's comments: As far as strain guages only measuring forces - you also have time and boat speed measures. Something in the back of my mind tells me that this combo can be used to effectively deduce work, but I haven't worked it out. Mike PS - I'll be away for a few days - how come the interesting stuff on Paddlewise occurs when I leave??? :-) *************************************************************************** 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/ ***************************************************************************
It is not that hard to figure out velocity if you have a good handle an acceleration so I think accelerometers could be used. It would not be as accurate as directly measuring velocity, but would probably be good enough if you can figure out how to calibrate it. With strain gauges I don't think knowing the speed of the kayak would be sufficient to deduce work on the paddle. Work on the boat, yes, paddle, no, unless you get the speed of the paddle (see accelerometer). A length adjustable shaft with interchangeable blades, strain gauges and accelerometers would be great. While we are at it, if we could put water speed sensors on various points on the blades, we would really have something. Nick On Friday, June 13, 2003, at 09:50 AM, Michael Daly wrote: > On 12 Jun 2003 at 21:30, Matt Broze wrote: > >> first). I think someone who came up with an electronic paddle shaft >> (that blades could be changed on) could sell such a system to several >> groups of people. > > Lendal's Paddlok system comes to mind, though you'd have to modify > other maker's blades to fit. If you get a variable length version, > then the widgets you plug into other makers' blades to adapt to the > Lendal shaft could be accomodated. You'd have to fabricate your own > adapter widgets, of course - no one sells such a thing that I'm aware > of. > > Paddle rotation may be measured, but gyros aren't the way to go. > Accelerometers only measure acceleration, not velocity, so any > constant velocity period in the stroke would be unknown (except in > duration). You might be able to make it work (integration of values > etc) but I'd have to think about it. There were MIDI based systems > that allowed people to "conduct" music by following thier hands > (without touching anything) - something like that could be adapted. > > On Nick's comments: > > As far as strain guages only measuring forces - you also have time > and boat speed measures. Something in the back of my mind tells me > that this combo can be used to effectively deduce work, but I haven't > worked it out. > > Mike > PS - I'll be away for a few days - how come the interesting stuff on > Paddlewise occurs when I leave??? :-) *************************************************************************** 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 13 Jun 2003 at 10:39, Nick Schade wrote: > With strain > gauges I don't think knowing the speed of the kayak would be > sufficient to deduce work on the paddle. Work on the boat, yes, > paddle, no, unless you get the speed of the paddle (see > accelerometer). You're right, of course. Once I reached further into the dusty recesses of my brain, I remembered that I always had independent measures of displacement to go along with time-vs-strain measures. > and accelerometers would be great. While we are at it, if we could put > water speed sensors on various points on the blades, we would really > have something. Nick Now it's getting tricky - though a sufficiently sensitive pressure measuring fabric could suffice and Bernoulli can help us deduce the local velocity. 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/ ***************************************************************************
Instead of trying to instrument the paddle, how about just painting a pattern on it and taking a movie in stereo? *************************************************************************** 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 13 Jun 2003 at 10:16, Jon Pumplin wrote: > Instead of trying to instrument the paddle, how about just painting a > pattern on it and taking a movie in stereo? Easy in principal, tricky in practice -perfectly doable. I once spent an afternoon with a film specialist in California next door to the deep sea testing tank where, years later, parts of Titanic were filmed (This was back in the days when I worked for a naval architecture firm specializing in ice mechanics - ice breakers, arctic oil exploration platforms etc). The lessons learned didn't greatly advance my own activities on filming tank tests ($$$ vs time vs willingness of clients to pay - spending $100,000 on a series of tank tests and then _not_ gathering good data seemed to most clients to be a good investment... Sigh - the lack of good data usually lead to further tests. Since this made my boss richer, he thought it was just fine.). The rather crazy California guy had created model oil rigs (semi-sub) with little grain-of-wheat bulbs (LEDs weren't well known by him) stategically placed on the model and then filmed the launching sequence in the tank using special (military surplus) high-speed registration film cameras. He then played the film back through a registration projector onto the back of a screen and _manually_ logged the position of each bulb so a computer could record the data (a servo-based system tracked the position of a pointer he placed on the screen and the computer logged the servo readings). A registration camera and projector ensure that adjacent frames of the film are in the same position - if you watch regular films (even Hollywood 70mm) where the frame edge is visible, you'll see the frames dance around a lot compared to a registration system. When you go through, say, 100 frames per second and then the entire several minutes of film, you've worn yourself out. However, the position info gave them accurate representations of the accelerations and therefore forces acting on the rig as it swung from lying on it's side to its final vertical position (not all rigs are built and launched this way - especially the big ones). He didn't use stereo lenses or film, but rather two cameras at right angles. With modern digital cameras, this could be done with a computer, especially if you rig different coloured LEDs and digitally filter out each one (say red, green and yellow and make the paddler wear blue in a blue kayak with a distinctly blue sea and sky). Digital cameras automatically self-register (fixed CCD position not moving film), but then the accuracy of the position info is dictated by the angular area of each pixel and the camera position relative to the paddler with appropriate corrections applied for perspective. If you have a 1000 pixel-wide field, and a field of view that's, say 3m wide at the paddler (ensure a 2.2m paddle stays in the field) then each pixel is nominally 3mm wide. You could probably interpolate the position to less that one pixel by watching pixel boundary crossings, but you'd also have to factor in what those Bayer algorithms do to physical vs logical pixels etc. Then you have to consider fixed camera position (fixed paddler; moving water) vs moving camera and then tracking the camera motion to convert relative to absolute motion etc. AFAIK, the software to do this you'd have to write yourself. Compared to that, the prospects of directly measuring the position sounds appealing. How to do _this_ remains to be seen :-) However, video based data logging is perfectly feasible. 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/ ***************************************************************************
[Moderator's Note: Content unaltered. Excessive quoting (i.e. headers/footers/sig lines/extraneous text from previous posts, etc.) have been removed. Please edit quoted material in addition to removing header/trailers when replying to posts.] It is a good idea to have volunteers and e-mail results. My concern is that people would have to have the two or three paddles to be compared, to have a report of relative speed between one and the other, so that you can cancel type of boat, ability, strength, etc.. I would be interested to participate and would like to hear your idea with more detail to understand what against what is going to be compared. Best Regards, Rafael. At 09:27 p.m. 12/06/03 +1000, PeterO wrote: >Rafael wrote: - > > one good approach that will give quantitative > > results, to be interpreted later by theory > > would be the STATISTICAL APPROACH. *************************************************************************** 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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