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Dave
A 50-foot wave by the Beaufort Scale means that you are in �exceptionally
high waves. The air is filled with foam and the sea completely white with
driving spray. Visibility greatly reduced�. The short description is
�hurricane�. You might want to check out
http://facs.scripps.edu/surf/luds.html, it has a very good and readable
description of predicting wind speed and wave height. In practice you will
not get a shot at anything because the wind and spray make it all but
imposable to hold the sextant still. I have been in these conditions and
speak from experience. By the way I think the height of a wave is measured
from the trough to the crest.
Robert Gainer


>From: David Weilacher 
>Reply-To: Navigation Mailing List 
>To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM
>Subject: Re: Level of observation accuracy in medium seas
>Date: Fri, 23 Jul 2004 06:42:03 -0500
>
>Hi Jarad;
>
>Can you point me to your source for Noaa wave height definition?
>
>Dave W
>
>
>-----Original Message-----
>From: Jared Sherman 
>Sent: Jul 22, 2004 9:34 PM
>To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM
>Subject: Re: Level of observation accuracy in medium seas
>
>Dave-
>  <50 foot waves with a mile between peaks.  I take my shot when my boat is
>at the top of a wave.  This is easy to tell because I can actually see a
>horizon.  The horizon I see is 8 miles away.>
>  Seems like short horizon. NOAA says that waves are measured from the sea
>level, not from the trough to peak, so are you talking about real fifty
>foot
>waves, or "real" 50 foot waves, which most sailors would call hundred
>footers?
>
>If the former, you're observing from 25' above sea level, figure ten more
>for your deck and standing eye height, since you've got a good enough grip
>to rider those doggies. That's 35' asf now, about your eight miles.
>(7.9+)
>
>Nah, you're only in 25' waves, that's the problem. Wait for rougher
>weather,
>you'll get a better horizon.
>
>But you could certainly figure the math. A sphere (close enough) 25,000
>miles in circumference, two points 8 miles apart on that. Change the radius
>of one by the 25' your far wave is blocking you...run some tangents and
>angles..."A simple exercise left to the reader."
>
>Just remember, you're only in 25' waves.
>
>
>Dave Weilacher
>.US Coast Guard licensed captain
>.    #889968
>.ASA instructor evaluator and celestial
>.    navigation instructor #990800
>.IBM AS400 RPG contract programmer

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