With two boats of the same waterline shape and radically different sectional shape, both boats will react in much the same manner when nearly upright. Where initial stability ends and "secondary" or "overall" takes over is subjective, but within a few degrees of upright, all that really matters is the distribution of the waterline. In other words if you take two boats and slice them horizontally at the waterline and the widths match at all points along the length , the initial stability will be the same (assuming the Center of Gravity [CG] is the same relative to the waterline). A cylinder will only have zero initial stability if the center of gravity is at approximately the center of the cylinder or above it. If you made the CG of the box just as high, you would get a similar response. But since a cylinder displaces less volume than a box of the same waterline shape, it gets complicated to compare using these models. Nick At 12:26 PM -0500 11/16/00, Coplan, Karl wrote: >Nick Schade writes: > >"Initial stability is dependant almost exclusively on waterline width. >Two boats with the same waterline width and shape will have the same >initial stability regardless of chine shape. Obviously, parameters >such as seat height and other factors effecting the vertical center >of gravity will also have an effect." > >Nick -- what do you mean by waterline width here? What you are saying >sounds extremely counterintuitive, unless I misunderstand what is meant by >initial stability. For example, imagine a box and a cylinder of the same >length and width -- they would have an identical "waterline width" (indeed >the waterlines could be identical shape and size. The cylinder would have >zero intial stability (and zero secondary stability) while the box would >have considerable initial and secondary stability. > >What am I missing here? > >--Karl Coplan > >P.S. sadly put my Coastal back in the basement last week after some 70 >Hudson River crossings this year! 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 Fri Nov 17 2000 - 09:24:19 PST
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