John Winters wrote: > > The discussion on the beam of folding kayak is interesting. I have tinkered > with some folding kayak designs just to see how the design of such boats > was limited by the structure. My feeling is that the limitations in shape > aren't significant. Yes, that is true. You can pretty much do anything you wish with a folding kayak or any skin boat for that matter. It is all in the frame and what you want to do with it. The Khatsalano is a good example of fairly radical design carried off by the frame setup. > > Many of the "features" of hard shell kayaks are not really advantages at > all even if they do make great advertising. When I played around with > models I did get the feeling that the narrower folding models might be less > rigid than wider boats just because the framework can be more greatly > stressed. > > Ralph will have a better feel for that in real life but maybe that is a > contributing factor. All the folding kayaks have some flex in them because they hardly ever have as many crosspieces as a regular skin on frame boat. But it depends on the manufacturer. All Folbots flop a lot. The others are much tighter. As a rule the Nautiraids may be the less floppy because they do have less intervals between frame members and the external sponsons tend to really stiffen things up somewhat more than internal sponsons. But other factors are apparent too. For example, the stiffest of the folders is the Feathercraft Short Touring model. It uses a good amount of crossribs plus square tubing which is more rigid than round. The Khats is the longest of the single folding kayaks at almost 18 feet in length. While slim, it uses an interesting strut set of deck bars that are set at angles. Years ago, I'm talking about back in the 1930s, some manufacturers used similar struts between ribs at the sides of the boat, for the same purpose, greater stiffness. > > As far as weathercocking etc. there is no reason that I can think of why a > folding boat need be any better or worse than a hard-shell. It's all in the > design not the structure I think. It is too bad that we don't have a good > comparison between two identically shaped boats to see if the differences > that we sometimes attribute to the two are really true. Unfortunately none > of our mathematical methods can cope with flexible frames and skins so all > we can do is analyze the shape. How true, I mean the measuring of what happens with flexible skin as it moves through water. I had a real lengthy article in my newsletter on the water dynamics by an award winning physicist who dealt with the issues involved. He came up with some interesting thoughts. I could reprint them here at some point. Or we could go off PaddleWise to discuss it as it can be pretty esoteric. ralph -- ----------------------------------------------------------------------- Ralph Diaz . . . Folding Kayaker newsletter PO Box 0754, New York, NY 10024 Tel: 212-724-5069; E-mail: rdiaz_at_ix.netcom.com "Where's your sea kayak?"----"It's in the bag." ----------------------------------------------------------------------- *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net ***************************************************************************Received on Thu Jan 29 1998 - 09:07:20 PST
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