Some of my replies were sent with text, but returned empty. Sorry about that. It might be the HTML formatting of my usual mails; this one is plain text. Here's my missing comments: Gerald Foodman wrote: > The idea that the potential energy stored while lifting the arms is then returned to move the boat forward is false, as is the pendulum analogy. Why? Supply some valid arguments please. > To move the boat forward the drag of the hull must be overcome by force on the paddle moving through the water and generating power. Thanks for stating the blindingly obvious. > This power must come from the paddlers muscles, and only after the blade is fully immersed. Which is untrue, which I explain with the clock-analogy, which you brush away without explanation, now to just repeat what you said before and why I brought in the clock. What's your argument why a clock can use potential energy to drive its mechanism, while a paddler can't? > It happens that I am an expert in classical mechanics. So am I. If you want to exchange resume's, that's fine - but I'd rather see solid arguments than credentials. By the way: to quote the list-rules: Remember to edit your replies by not including the entire message to which you are replying. Delete the parts that are not relevant and delete the PaddleWise trailer. Continued unedited messages may cause your messages to be edited by the listowner, in the event of recurring non-editing your email may simply disappear. Please do me the courtesy of abiding by the rules. ------------------------------------------------------------------------------------------------------------------------------------------- Carey Parks wrote: > Hi Niels, > > I have been telling friends to "rest their arms on the paddle" while coaching them in the forward stroke, and I think many of them think I'm nuts but are too nice to say anything to me. I will share your video with them As we've seen, my video proves little to those that do not want to be convinced. I'm planning another video, a very short one, that proves beyond any doubt that the concept works. > and borrow your paddle against the dock idea to see if I can communicate it better. I've tried it last year, but without standing next to them to shape their body and arms and support the paddle with a thigh before letting it rest in the water. Some people find it very hard to copy a movement or posture and really need to be molded physically. > In addition to the longer rest aspect of torso rotation, I do feel that the uncoiling of the back adds additional rearward force to paddle during the stroke, giving you more dynamic support for the paddle (and thus the arms) than paddling with the arms alone. If your shoulders are at rest, letting gravity do the work, then I don't think any movement of your torso will change the force on the paddleblade. Any movement of your torso will be compensated by your arms moving down faster of slower. I think it will only work if you actively drive your arms down at the same time. > Oh, and I guess if you are the kayak, the arms moving down and back is the "power" phase of the stroke, but if you are the arms, it would indeed be the rest phase. So it becomes a perspective issue doesn't it? It is both the power phase and the rest phase at the same time. Well put ;-) Thanks for your support, Carey. It's nice to know that I'm NOT alone. Niels ---------------------------------------------------------------------------------------------------------------------- Gerald Foodman wrote: > Take two limiting cases. First the wing stroke: Once the blade is fully immersed at the catch, the power phase is almost all hips and torso, with the upper arm staying at the same level as the upper wrist passes in front of the face to the opposing side. Meanwhile the wrist near the immersed blade also stays at the same level. So during the power phase there is no, or minimal, change in altitude of the arm, and hence no change in potential energy. > I take the first "related video" from youtube, from the link of my own video: http://www.youtube.com/watch?v=EZyWohPcER4&feature=related . If you watch her stroke, and especially the middle of the paddle, you will see it move down during the "power"phase. She could make more use of gravity, by dropping her hands and paddle further. Meanwhile: I thought you were arguing that turning potential energy into forward motion is _impossible_. Your exact words were: To move the boat forward the drag of the hull must be overcome by force on the paddle moving through the water and generating power. This power must come from the paddlers muscles, and only after the blade is fully immersed. and It is called the power phase because that is when the power that moves the boat forward is applied. While changing sides, no power at all is applied to moving the boat forward. Did you drop that argument? > Second case is a very low Greenland type stroke as taught, for example, in Doug Van Doren's video. Again there is very little altitude change of the arms during the power phase. > I'm not talking about a greenland stroke - and neither am I talking about rowing, motorboats, spacecraft or nuclear explosions. Let's stick to the topic: I'm talking about the normal kayak touring forward stroke. *************************************************************************** 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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