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/ ***************************************************************************Received on Thu Jun 12 2003 - 21:25:22 PDT
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:31:07 PDT