Just to fill in with some of the back channel response to Matt's comments: I am not ready to eliminate the backside of the curve yet. Even if you go over the hump with some momentum, the backside of the curve is absorbing energy and offers at least the theoretical potential of slowing you down. Also if you do stop your momentum by bracing, the stability shown on the backside of the curve will be enough to right you without additional help from a brace. It may be a slow recovery, but it will happen as long as no other forces come to push you back down. The area under the curve from zero to the angle of heel is the potential energy built up that is ready to push the boat back upright. If boat reaches the point but is still moving, it still has kinetic energy left to absorb. If the area remaining on the curve is less than the kinetic energy of the rotating boat, it will go over, otherwise it will stop. A boat with a lot of area under the backside of the curve will be able to absorb a tipping hit better and will require less bracing energy to stop the tendency to capsize. This points to the backside of the curve being more important in dynamic situations where some capsizing impulse has to be absorbed. Nick >At 3:51 AM -0800 11/21/00, Matt Broze wrote: -snip- >To put this all in layman's terms, it looks to me that what the paddler >feels is >the stiffness (slope of the curve) and when that stiffness starts to >decrease significantly is when the paddler is going to get nervous. This >pushes the critical angles for "secondary stability" (or whatever we choose >to >call it) even further to the left than I had imagined (and I have been >moving >to the left from how I first looked at secondary stability on the curve >progressively). First I thought the capsize point had some significance but >then John Dawson's >explanation convinced me to retreat to near maximum stability as the >critical >point. Then his explanation of how the test boats capsized uncontrollably >beyond >the maximum righting moment caused me to believe that the critical point was >probably >somewhere between the point of maximum stiffness and the maximum righting >arm. In other words, if one moved beyond the break in the Pisces' curve's >steep upward slope (where the stiffness drops off quickly) they will have >gotten into an area (beyond an angle) where you couldn't trust that any >momentum would be absorbed by the increasing stability. (If you read it, >this >is what I was trying to point out with the first ramp example where I >suggested it would be hard to roll a ball bearing up and over the break in >the Pisces curve without also going all the way over the top). -- Nick Schade Guillemot Kayaks 824 Thompson St, Suite I Glastonbury, CT 06033 (860) 659-8847 Schade_at_guillemot-kayaks.com http://www.guillemot-kayaks.com/ >>>>"It's not just Art, It's a Craft!"<<<< *************************************************************************** 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 Tue Nov 21 2000 - 14:05:56 PST
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