Niels wrote: >You KEEP dividing those 30 watts by two. I maintain that >you're wrong in all those cases: G'day, Regarding using one or two arms in the calculation of potential energy created by lifting a paddle and the associated power (PE). To the extent that a paddler is lowering both arms simultaneously during the power phase of a stroke then I can see that its justified. However, when carrying through the power stroke my upper hand is held level in the horizontal plane, and passes across my eyes, so I should only use one arm in the calculation of PE for my stroke. Regarding using another factor of two as a crude approximation to account for the times in a paddle stroke when there is no lifting of either blade. The justification is that: 1. during the power stroke I rotate my torso to engage my abs and also to extend the blade's path through the water so that in the later phase of the stroke the blade is neither falling nor rising. 2. few paddle strokes are truly carried out in the vertical plane. Consequently the blade seldom travels quite parallel to the side of the boat but tends to sweep out as it travels backwards and this also has the effect of maintaining the blade at a constant level below the surface of the water during the later phase of the stroke So with the upper hand at a constant level throughout the power phase and with the blade at a more or less constant level below the water during the later phase of the power power phase there is a significant period in my stroke when my arms are static with respect to my torso and I am neither releasing nor creating potential energy due to change in blade height. Thats why I need to use some compensating averaging factor to evaluate the continuous power generated or used. All the best, Peter *************************************************************************** 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 Sun May 01 2011 - 13:43:22 PDT
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