At 5:05 PM -0500 1/17/02, Michael Daly wrote: > >Actually, long boats need higher speeds to plane. To plane in white water, >you'd need a short boat. (I'm not going to partake in the debate over >planing vs surfing anymore). > >Basically, to plane, you need to hit a speed/length ration of 1.5 or greater. >The speed/length ratio is the speed divided by the square root of the length. >This is familiar, as hull speed is defined as a speed/length ratio of 1.34. >So you have to go at least 12% above hull speed to plane (ICF racers in >kayaks excede this without planing - not a planing hull). > >A long, wide WW kayak will be a displacement kayak unless you get into some >really scary water velocities. A short narrow kayak will sink :-) I think as a practical matter this is probably true. But as a thought experiment get a short little WW kayak surfing on a wave and up there planing along nicely. Now start building a lightweight extension on to the bow. Light enough that it doesn't effect the trim or displacement. At what point does the fact that the boat is longer make it so it stops planing? If you were able to extend the bow out 20 ft without effecting the trim, would the fact that the boat is now 26' long and the water speed has not changed really made it so the boat is no longer planing. I think a definition based on speed/length ratio does not really capture what we understand planing to really be. I think a definition that incorporates the actual actions of the boat is more meaningful than the one that specifies the power source or length vs speed. I like the definition where the boat lifts up and drag is reduced. If a long boat can do this a low speed or a short boat can do this with an external power source, so be it. Of course since I am not the arbiter of the English language I guess it is not my call. -- Nick Schade Guillemot Kayaks 824 Thompson St Glastonbury, CT 06033 (860) 659-8847 *************************************************************************** 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 Jan 18 2002 - 08:38:05 PST
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