My thought why the greenland paddle works so well is: kayaks are easy boats to propel. Once you get them moving, you don't need a powerful grip in the water to keep them going. Since the energy wasted is a function of v^2, if you don't have to push the water very hard, you don't waste a lot of energy. I would not want to move an oil barge with any kind of paddle. Kayaks are good boats, thats why the paddle works so well. At 4:17 PM -0700 7/23/98, Julio MacWilliams wrote: >Yes, there is lift. However, Nick is saying that the lift contribution >to forward motion is very small, which seems to be a valid claim. > >The effects of the lift are dramatic when doing rolls, braces, and sculls, >but even though one can feel the lift also when paddling forward, >that lift is much smaller than when doing rolls. > >There has to be something else going on that makes the Greenland >stroke so powerful, as it is hard to believe that such a thin stick >would move you forward at all. > >Maybe the combination of foil shape and narraw blade creates a fast >eddy around the paddle that provides the mass*velociy factor necessary >to provide a good momment of inertia to the kayak (m*v = M*v') > >Whatever it is, the Greenland paddle works incredibly well, but >the real reason why remains a mystery. > >If there is ever some serious scientific study aimed at improving or >refining Greenland paddles, then we might know. > >- Julio > >K in response to Nick wrote: > >> > This concept has been brought up before. The idea that the greenland >>paddle >> > uses lift to propel the boat just makes no physical sense. The paddle just >> > does not move far enough laterally through the water to provide >>significant >> > lift. It, like most paddles is being used primarily as a parachute, not a >> > wing. >> > >> >> This is simply not true. I have a degree in physics as well, and it makes >> perfect physical sense to me. The greenland paddle in its three main >> varieties of strokes has a high lateral component of velocity at the ends >> of the paddle. With the proper angle of attack and with a well constructed >> foil shape, there is laminar flow across the paddle, and lift is generated >> in the opposite direction of which the paddle is being pulled. Learning >> how to make the lateral velocity of the paddle fast enough to generate >> lift takes a fair bit of practice -- I can do it reliably in two of the >> three kinds of strokes. Come to Seattle and I'll show you. Greenland >> paddles generate lift. >> >> Nick Schade Guillemot Kayaks c/o Newfound Woodworks, 67 Danforth Brook Rd, Bristol, NH 03222 (603) 744-6872 Schade_at_guillemot-kayaks.com http://www.guillemot-kayaks.com/ >>>>"It's not just Art, It's a Craft!"<<<< *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************Received on Fri Jul 24 1998 - 14:30:09 PDT
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