On 8 Sep 2004 at 14:52, Robert MacDonald wrote: > It forces me to make what assumption? The ventilated blade behaves > quite differently, as I can both see and feel. Well, that's one thing I'm getting at. If you can see the behavior of the interface between water and air when ventilated, it tells you nothing about the behavior of the paddle without ventilation. Hence, only a formally done test with standard indicators would be useful. > Some pretty amazing claims for the efficiency of high aspect ratio > blades have been made in this forum. I am still trying to fathom why > they do work as well as they do. They work well at certain things and not at others. I seem to be one of the only ones that claims that GPs are less efficient than Euros. There is some test evidence and some theoretical indications that would support that assumption. I know of no real solid evidence against this assumption. Test evidence includes tank tests that show efficiency increases as aspect ratio decreases. The theoretical is limited to the observation that moving large amounts of water at low velocity is more efficient than small amounts moved fast. It would appear that the GP does more of the latter. I also know that my GP will tire me out more than my Euro, though the Euro is tougher on my joints. Many others report the opposite fatigue effects, but personally, I question the objectivity. Personally, I was quite sceptical about the advantages of a GP over a Euro, so I had to be convinced by using and comparing them. I had no prior or current reason to convince the world that one is better than the other, hence I think I'm being relatively objective (though I may be incorrect - I can't _measure_ the fatigue effects). I favour the GP mainly because it's easier on my joints and I really like the fact that it's a lot quieter than any Euro I've used (I paddle in large part for peace and contentment - big wave thrills aside :-) It remains to be seen whether the efficiency can be measured to be greater or less. Mike *************************************************************************** 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 Wed Sep 08 2004 - 16:31:09 PDT
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