Strictly speaking, Matt, his question was not "What is primary/secondary stability," but "How is it measuredd?" Is there an adapter to hook a torque wrench onto the bow of a boat? Mike Wagenbach *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
I was not dodging the question just trying to explain the problem. If you don't agree on what secondary stability is you can't measure it. Stability can be measured using a torque wrench and a fitting that clamps to the boat. Sea Kayaker magazine did it this way in their 1986 kayak tests. Now they measure the shape and input that data into a computer program that claims to draw a stability curve. I say claims because it doesn't look quite like the previous torque wrench curves especially at very high angles of tilt. Primary stability is measured by how much torque is required to tilt the boat the first few degrees. I have never heard of a measurement of secondary stability but I would love to hear about it if someone else has. Matt Broze http://www.marinerkayaks.com -----Original Message----- From: M. Wagenbach <wagen_at_u.washington.edu> To: PaddleWise_at_lists.intelenet.net <PaddleWise_at_lists.intelenet.net> Date: Wednesday, August 11, 1999 12:01 PM Subject: Re: [Paddlewise] PaddleWise V1 #646 >Strictly speaking, Matt, his question was not "What is primary/secondary stability," but "How is it measuredd?" > >Is there an adapter to hook a torque wrench onto the bow of a boat? > >Mike Wagenbach > >*************************************************************************** >PaddleWise Paddling Mailing List >Submissions: paddlewise_at_lists.intelenet.net >Subscriptions: paddlewise-request_at_lists.intelenet.net >Website: http://www.paddlewise.net/ >*************************************************************************** *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
On Wed, 11 Aug 1999, Matt Broze wrote: > I have never heard of a measurement of secondary > stability but I would love to hear about it if someone else has. Does a weighted lever arm attached to a kayak meet your requirements? Adding weights to generate a stability curve? A few years ago they did this at a Maine Island Trails association meeting for an assortment of boats. This seemed to be a reasonable interpretation of secondary stability. The problem with their results was they used a different person in each boat instead of testing a boat with a dummy or sand bag for a paddler. The boat that took the most weight to capsize felt to me to have the best secondary stability, it was woodstrip kayak from Loon boatworks in Maine, with a generous amount of flare behind the cockpit. kirk *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Weight out on a bar or a torque wrench (essentially the same thing) will do to measure stability. But that isn't secondary stability unless we agree on a definition of at what angles of lean and/or what characteristics constitute secondary stability. Even using the same person with each boat could not be counted on to yield consistent results because that person could lean differently (but way better than using different paddlers). Matt Broze http://www.marinerkayaks.com -----Original Message----- From: Kirk Olsen <kolsen_at_imagelan.com> To: paddlewise_at_lists.intelenet.net <paddlewise_at_lists.intelenet.net> Date: Thursday, August 12, 1999 9:08 AM Subject: Re: [Paddlewise] PaddleWise V1 #646 >On Wed, 11 Aug 1999, Matt Broze wrote: > >> I have never heard of a measurement of secondary >> stability but I would love to hear about it if someone else has. > >Does a weighted lever arm attached to a kayak meet your requirements? >Adding weights to generate a stability curve? > >A few years ago they did this at a Maine Island Trails association >meeting for an assortment of boats. This seemed to be a reasonable >interpretation of secondary stability. The problem with their results >was they used a different person in each boat instead of testing a boat >with a dummy or sand bag for a paddler. > >The boat that took the most weight to capsize felt to me to have the best >secondary stability, it was woodstrip kayak from Loon boatworks in Maine, >with a generous amount of flare behind the cockpit. > >kirk > >*************************************************************************** >PaddleWise Paddling Mailing List >Submissions: paddlewise_at_lists.intelenet.net >Subscriptions: paddlewise-request_at_lists.intelenet.net >Website: http://www.paddlewise.net/ >*************************************************************************** *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
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