Ralph wrote; (SNIP) >Which brings up the question of payloads and how accurate they are. The >Klepper single claims 550 pound payload!!! Can that really be? I know >it can carry a lot, but that figure is a lot too! > >I suppose payload limits may be a matter of how much freeboard you feel >comfortable with and whether you want to supplement it by wearing a >snorkel :-) This business of payloads presents a problem because few designers actually design around a payload and few builders actually publish realistic load ranges. By "realistic load range" I mean a load range at which the boat will be safe and still perform as intended. I know of no easy answers but in an effort to provide some simple guidelines I studied the boats in my database and compared paddler perceptions with displacement. Hardly science but this is what resulted. It seemed that good paddlers could notice (in a crude way) a change in performance within a range of +/- 5%. My reading into Psychokinetics suggests that I was overly optimistic). Using this as a base and recognising that a whole lot of measurements might not be available or convenient I created a table based on this information and a form factor called the "Fatness ratio". The fatness ratio is the volume of displacement divided by (0.1* waterline length)^3. Since the performance range seemed to fall within fatness ratios of 0.95 and 1.6 I set those as range limits leading to the following table; WL Length 12 13 14 15 16 17 Low limit 105 133 166 205 249 298 High Limit 176 224 280 345 419 503 Of course, you all will recognise that boats don't become instant water pigs when outside the range. It could be called a "fuzzy" range. I don't pretend that this guarantees anything but it might be a useful guide where nothing else exists. There was a short article that went with the table (and a graph of the table but you all have spreadsheet programs and can make up your own graph labelling it "John Winters' Absurd Theory of Loading"). 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/ ***************************************************************************
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