Peter wrote: > > I doubt there would be anything to gain by making a hull rough. A paddle > may > be a different issue however.... > True enough and "How" you make it rough would make a huge difference. Various techniques of "structuring" the surface such as microgrooves seem to have limited benefit. In the America's Cup boats many believe the structuring done had a greater psychological benefit than physical benefit. I have been shown another method using small "wedges" but it seems heavily dependent on flow alignment. In any case the roughness (dimples) of the golf ball serves a purpose for which a boat has little or no need, i.e. reduction of separated flow. For kayaks separation is a very small part of the total drag probably not noticeable to paddlers. Still, it would be nice to have some one isolate the separation drag for different stern configurations. Matt and I discussed this back when I was creating KAPER and, with Matt's assistance, converting to something useful for Sea Kayaker . I didn't feel confident that I knew enough to incorporate a factor for it then and still don't. Maybe Matt has something new to add now as he has been using KAPER for Sea Kayaker for some time now and may have more data to work with.. Rough paddles have been tested a bit with mixed reviews. My own "Gravel Paddle" seemed to reduce flutter and maybe improve thrust but looked horrible (Even I wouldn't use it). Some aero research on paddles done at the Air Force Academy with holes in them showed reductions in flutter without affecting thrust. Not a very comprehensive study though. Lots of room for experimentation. 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/ ***************************************************************************
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