Nick Schade wrote: >More apparent slippage is inefficient. Why? Say you had 100% "slippage". You have no propulsion, but at the same time, almost no effort. We've been playing fast and loose with this idea of "slippage". Now there *is* such a thing as a zero-slip canoe paddle; it's called a canoe pole, and my friend Jeff Potter could tell us all about it. But a pole is used in a very different way from a paddle specifically because of the much higher resistance. You couldn't paddle the way we're used to with a "zero-slippage" paddle. The effort would be way too high. So human biomechanics dictate that our paddles can't produce too much resistance. >...You must accelerate > water to propel the boat, but the more you accelerate the >water, the less efficient your paddling will be. This I don't follow. *Any* energy you impart into moving water backwards will result in moving your kayak forwards. >.. Any >acceleration of the water is energy imparted to the >water which would more efficiently be spent moving your >kayak. Same thing, isn't it? Newton's second law. >...Your goal therefore is to maximize the mass. You can trade off mass vs acceleration. What makes for efficiency in the long haul is biomechanics- how to extract the maximum useful work out of the paddler. -- mike --------------------------------------------------------------- Michael Edelman mje_at_spamcop.net http://www.foldingkayaks.org (nomadics) http://www.findascope.com (choosing a telescope) *************************************************************************** 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/ ***************************************************************************
Michael Edelman <mje_at_spamcop.net> wrote >We've been playing fast and loose with this idea of "slippage". Now >there *is* such a thing as a zero-slip canoe paddle; it's called a canoe >pole, and my friend Jeff Potter could tell us all about it. But a pole >is used in a very different way from a paddle specifically because of >the much higher resistance. You couldn't paddle the way we're used to >with a "zero-slippage" paddle. The effort would be way too high. > >So human biomechanics dictate that our paddles can't produce too much >resistance. Why can't you paddle with a pole the way you do with a paddle? If you give me a pole that is as long as my paddle (from hand to hand to centre of effort) and a fixed point to place it in/on/against then there will be virtually no difference between it and paddling in water except for a little slippage. Biomechanically the distance between pushing hand, pulling hand and fixed point (centre of effort) are the governing factors. Admittedly finding something to place the pole against equivalent to the c of e's usual acting point might be a little difficult. The length of a usual poling pole and the depth needed to find something to work again dictate a difference in action - the DEPTH of the WATER. Now we come back to my comment earlier about effort in the push as well as the pull - if the upper hand placement, lower hand and the centre of effort distances are all considered then the pushing hand is pushing with a force of a certain amount, proportional to the pulling hand. I'll let you work it out, simple levers. Alex Alex (Sandy) Ferguson Chemistry Department University of Canterbury New Zealand *************************************************************************** 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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