Something I posted on rec.boats.paddle.touring. Thought some who don't subscribe might be interested. --------------------------------------------------------------------------------------------------- A couple of weeks ago some folks were discussing (and getting confused about) hull speed and the relationship to length. I pointed out that it's not a speed limit and that kayakers can exceed the hull speed. Let's take a look at Caroline Brunet's finish in the qualification round of 500m K1. Time over 500 m = 1min 54 sec. This is equal to 1.90 min. Speed = 0.5 km * 60 / 1.9 = 15.8 km/h. LOA of kayak = 520 cm* (not sure of the LWL, but using LOA will overestimate the hull speed). = 17.06 ft. Hull speed = 1.43 sqrt( 17.06 ) = 5.91 knots = 6.79 mph = 10.93 km/h. Her peak speed would have been greater than 15.8 km/h, since she started from a standing start. Therefore, we can safely say that she exceeded the hull speed by at least: 15.8/10.9 = 1.44 or 44%. As you can see, hull speed isn't a limit. It is just the point where the paddler has to start doing a lot more work for the speed they're going. Mike * I'm not exactly sure if this is the right length. It's the only value I've found for ICF flatwater K1. Is there a web site that lists the ICF K1 specs? I couldn't find one. Is it the same as the Olympic spec? *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Michael wrote: SNIP > As you can see, hull speed isn't a limit. It is just the > point where the paddler has to start doing a lot more work > for the speed they're going. Good that Michael and others are trying to straighten out this misconception about hull speed. I remember when I first explaine this in the old Canoesport Journal and some of the great lights in canoe design threatened to have me drawn and quartered for spreading heresy. I once asked an expert to paddle a measured course at top speed. When the calculations showed he had exceeded hull speed by a considerable amount he swore I misread the stop watch. So deeply can our beliefs become entrenched. One minor but important detail. In sprint kayaks and canoes "hull speed" has almost no meaning at all since wave making resistance doesn't become an overly large proportion of the total resistance at any speed. You don't even have to race to attain high speeds. Even my old body can reach high speed/length ratios in short bursts. > * I'm not exactly sure if this is the right length. It's the > only value I've found for ICF flatwater K1. Is there a web > site that lists the ICF K1 specs? I couldn't find one. Is it > the same as the Olympic spec? Olympics don't have any specs, (some would say thank God) and the boats are governed by the ICF. The horns just behind the cockpit are rule cheaters to make narrow boats that still meet the beam minimum. The ICF has a tradition of illogical rules and even more illogical enforcement. Cheers, John Winters Web site address http://home.ican.net/~735769 *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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