Chuck wrote; -- > >There are apparently several, not just one way, to measure waves. As >explained in David Burch's book, <underline>Kayak >Navigation</underline>, p. 298, the Canadians publish wave data in a >measurement called "significant wave heights." Swell is illustrated on >at least some of the canadian charts showing the direction and height >of the various components (i.e. a vector which illustrates the swell >from the cardinal points about the compass). I could not find an >example of these vector diagrams, but I have seen them, I think in the >Canadian Sailing Directions (my copy got left in a motel room >somewhere). One should not confuse the way wave conditions are reported versus the way individual waves are measured. The measurement of wave height is the distance from trough to crest or twice the amplitude. The confusion may come from assuming wave height and amplitude are the same thing. The reporting of wave conditions - average wave height, significant wave heights, etc. - are based upon many waves not individual waves. If I recall correctly the original question had to do with observations of individual wave heights not observations of wave systems. A minor point perhaps but, as Chuck points out, there is a difference between individual waves and wave heights as reported by a sea condition report. One should not assume that because wave heights are reported as being 1 meter that they will in fact be 1 meter. They will cover a range some being much higher and some much lower. Height is but one factor. Perhaps of greater interest to paddlers will be ratio of length to height. It is the steep breaking waves that cause capsizes not the long gentle old rollers. Generally for waves of the same height new waves are steeper than old waves and waves in shallow water are steeper than waves in deep water. One can put this information to good use. You can avoid steep waves by staying offshore where waves are unaffected by shoaling water and can pay heed to changing weather conditions that will create new wind driven waves. 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 Fri Sep 04 1998 - 17:42:16 PDT
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