JCMARTIN43_at_aol.com wrote: > > Okay, I admit it. I don't know how to measure a wave. Is the "height" of a > wave the vertical distance from the bottom of the trough to the top of the > crest? Or is it from the mean? Or what? What's the real technical answer? [snip] > So what's the official way of measuring stuff like this? (And does it really > matter?) Well, probably the most popular method is crest-to-trough, at least for people who surf. And for surfer dudes and dudettes, that would be the maximum height, just as the wave breaks. The swells you mentioned in Baja, which you estimated as 8 footers, would be larger than that if they formed surf. As swells reach water much shallower than the distance between crests (the wavelength), their wavetrains begin to shorten the distance between crests, and at a depth about twice their height, they "peak up," breaking at a water depth of about 1.3 times their height. So, a wave's "height" will depend on where in its lifetime you encounter it. If you get interested in this stuff, Joq, locate "Waves and Beaches," by Willard Bascom, Anchor/Doubleday, 1980, ISBN 0385148445. This is the classic treatise (for the lay public, anyway), and is written in very readable style. Probably out of print, but any decent earth-science section in a public library should have it. You would have liked Bascom. He and his cohorts did leadline and transit surveys of many high-energy Pacific beaches, surfing "double overhead" stuff (surferese for 12 footers) in Army Dukw's -- amphibious vehicles dating fromn WW II. Nowadays, we'd call Bascom a s**tkicker. In those days, they did not know any better. (No PFD's, no wet suits or dry suits, just lots of chutzpah!) -- Dave Kruger Astoria, OR very ancient surfer -- when boards were made of balsa *************************************************************************** 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 Thu Aug 27 1998 - 21:04:09 PDT
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