Peter wrote; >I've read that if foldables or hardshells are partially filled with water >then the sponsons make the foldable more stable. Only if the hard-shell does not have reserve buoyancy or a pod or sea sock. The flotation in concert with the shape provides stability. So far I have seen no support for the argument stability have seen a number of studies on this topic and performed some myself with no suggestion that the hull materials have any unique properties. >That makes sense from a >physics point of view. The foldable would be underdamped and the hardshell >very damped! I've not seen significant deformation in the Klepper expedition >sponson when submerged so not convinced that sponson deformation improves >stability. One has to include free surface effects in any discussion of stability in a flooded state and one can reduce free surface effects in boats of any construction materials. In all of these discussions one must compare apples and apples and not confuse the occasional Valencia with the Granny Smiths. :-) Peter also commented on energy absorption (in another post) of the flexible hull and this may have some merit. Typically, the kayaks have so little mass that the energy from a wave tends to sweep them along rather than doing serious damage unless the boat gets capsized and the wave comes crashing down on it. In this circumstance one has to factor in the thee capsizing moment of the boat. A boat with high initial stability tends to capsize more easily in a breaking beam sea than one with low initial stability. If everything but hull construction remained equal, one might find a difference. Not sure, if it would matter much. Perhaps one of you bored engineers could do the calculations. Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************Received on Sun Apr 11 1999 - 09:29:17 PDT
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