It came to me that the tug of war has little or nothing to do with speed. It may have more to do with mass i.e. the mass of water moved by the Mirage versus the mass of water moved by the paddle. The mirage power unit certainly is clever and interesting. The picture of the tug-of-war suggested a lot of slippage in the paddles suggesting that larger paddles might have produced a different result. Cheers John Winters *************************************************************************** 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/ ***************************************************************************
The video is very impressive, but something hits my thoughts. I have raced (some years ago, Virginia 2000) a Mirage. I was not impressed by the final speed. I was pretty close in a slow Hydrobike. Novice kayakers were even and some more skilled beat the Mirage. Of course it appeared to depend on the user, but, considering the tremendous difference in the video, I don't think the rider would make that big a difference. I think the point is that in the tug-of-war the Mirage power output is all used in propelling (Its efficiency is optimum at standing still). On the kayak at rest the paddlers efforts go in displacing water to the sides of the paddle (its efficiency is worst at rest). The opposite happens at full speed. The paddle power is used just to displace the boat with little side water displacement, since the paddle stays (more or less) in the same spot and the kayak has some inertia. So most of the power goes to defeat water friction on the hull, and to keep momentum. On the other side, at speed, the Mirage finns move against moving water, and assuming the strokes pace is the same as in the stand still condition, then the water pushed is less and less, the faster the boat goes, because water is already moving away from the finn. The pressure that the standing water put on the finn to give maximum force is much less with water displacing backwards. The rider can increase his pace, but there is a human endurance limit, and therefore the power efficiency decreases with speed. Therefore I suggest a test in which Gregg Barton and the Mirage rider, in identical boats, pick up speed and pass the starting line at the same time. I can bet that the kayaker will win in a sprint and in a long distance run. The video is a very clever way to show the Mirage power, but tug-of-war is not the usual way to use human powered water vessels. Best Regards, Rafael El caycuochief Mexico *************************************************************************** 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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