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Subject: Re: Explanation by Mr. Stark needed
From: Royer, Doug (doug.royer@XXX.XXX)
Date: Thu Jun 12 2003 - 15:09:06 EDT
Bruce,thank you for your time and explaination.I appreciate all the info and
advice I can get on any subject from the listmembers.There are so many
differant ways to look at and/or do things.I wish to digest the information
and proceedures pertaining to this Lunar subject before I ask anymore
questions.I hope to try this new (to me)proceedure over the next few days
and try to form my own opinion as to the diffaculty or ease of completeing
it.Personally I am more experianced and comfortable takeing altitudes than
measureing angles across the sky from contorted bodily positions.
As for the thread on towing a log,sure,it's a stretch to consider it a legal
tow.However,as explained by the inspector,in the narrowest interputation of
the law it can be considered as binding because there is no physical size
limit to a towed object.Someone more versed in the law would have to make
that final decision and the tower would have to decide if the hassle was
worth it.
George,without meaning to be argumenative,check the Colregs as there are
proscribed signals for a tow < 200 m in lenght.
Jared,I'm still waiting for your responce to my inquiry reguarding the
double 4 sight round example.
-----Original Message-----
From: Bruce Stark [mailto:Stark4677@XXX.XXX]
Sent: Thursday, June 12, 2003 10:12
To: NAVIGATION-L@XXX.XXX
Subject: Re: Explanation by Mr. Stark needed
Doug,
Please don't hold me to my statement: ". . . the moon being east or west of
you doesn't mean you are west or east of her." I was thinking DUE east and
west. In other words, a body's position angle is hardly ever the reciprocal
of
the azimuth. This is easily demonstrated with a piece of string on a globe.
The ideal situation for getting local time or longitude is when a body is
due
east or west. That's when it is perfectly in line with the motion you want
to
measure, the earth's rotation. But to get GMT from the moon you have to
measure the moon's motion along her orbit. The earth's rotation has nothing
to do
with it.
Years ago, I picked a time from the Almanac and set up a hypothetical
situation where a boat was expecting to be entering the English Channel in a
few
days. Night was falling and weather making up, but the single-handed
navigator got
a good cut with two stars, and the altitude of the moon. His LOP lunar put
the boat well out in the Atlantic. Reassured, he went below.
Trouble was, he was just west of the Scilly Islands. Although the moon was
within 5° of due west, and all three altitudes more accurate than could be
expected, the observation was a disaster. The moon's orbital motion, as I
recall,
was out of line with her altitude by 79°.
Bruce
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