Nick wrote: >I question whether the paddlers body adds much damping which is significant >to how easily the boat rolls. Even people with terrible technique can >usually get their body to the surface of the water without much effort. In >a roll like the c2c the body is used to push against the water so the drag >of the body in the water is actually a good thing. Observe the freaks who >can roll with their hands behind their head. John commented negatively on this. I'm arguing from my own experience, which is primarily (as far as rolling is concerned) in whitewater boats. I think my body movement in the roll is small, relative to the water: I tend, if I remember correctly, to lie out near the surface before the roll motion starts. I'm not as negative on rolling as John is, but I tend to try to avoid them, and I haven't done any since a few practices last year, so I'm afraid my memory is a bit vague. My memory is that my body motion is intended to minimize its motion through the water, so the drag of the body is minimized. > >I agree that damping will play a part, however again since the hardest part >of the roll seems to be the last 100 degrees or so, I don't think that >upspwept ends will play a large part. A rudder would tend to be more of a >hinderance than an upswept bow. > >I don't see that the rolling period of the inverted boat would be that >pertinant as it would mainly provide information for a orientation which >most people don't have any problem getting beyond. I suspect it depends on how well the roller "listens" to the situation. If you try to do an instant whitewater roll in a heavily laden sea kayak, the difference in roll periods will hurt you. If you recognize that you need to do things more slowly, no big deal. >{snip} >It seems to me that a boat that is easy to roll will be easy to roll showly >or quickly. Damping would be related to how fast the boat rotates. This >would suggest that the dynamic part of the equation would be less important >to whether a boat is easy to roll. I disagree here, Nick. Things that stick out, like keels, rudders, chines,... can make it nearly impossible to roll a boat quickly while the static stability characteristics, whatever ones are relevant (which was your original question, and I don't know the answer either), can make it very easy to roll slowly. So the question is as usual more difficult than one might at first hope. Bruce Winterbon bwinterb_at_magma.ca http://magma.ca:80/~bwinterb The only sustainable growth rate is zero. *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Wed Jul 05 2000 - 04:57:02 PDT
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