NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: The Noon Fix
From: James N Wilson
Date: 2009 Apr 11, 14:17 -0700
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From: James N Wilson
Date: 2009 Apr 11, 14:17 -0700
Gary:
You wrote:
Why not just cheat?
For the short period between the two observations simply change your
course to straight east of west, that eliminates the problem of vessel
movement. Even better, adjust the course slightly north or south of
east or west to create a vector north or south movement to compensate
for the change in declination of the sun.
For the short period between the two observations simply change your
course to straight east of west, that eliminates the problem of vessel
movement. Even better, adjust the course slightly north or south of
east or west to create a vector north or south movement to compensate
for the change in declination of the sun.
I'm a sailor and course changes are not trivial, and usually dependent on
the wind. I've never worked for a captain who would change his course for an
hour for the convenience of the navigator. As a backup to GPS, the method would
be used in emergency conditions, when arbitrary course changes would
not be prudent.
And:
That said, I don't see any advantage over the traditional method
of
advancing the morning sun line to cross the afternoon sun line.
advancing the morning sun line to cross the afternoon sun line.
The advantage over calculating lines of position is that there is no
calculating. The arithmetic involved is only addition and subtraction. I note in
the referenced paper that "Since plotting runs of sights is always recommended,
no extra work is involved there, and the few computations are significantly less
than reducing a pair of sights and plotting them to get a fix." And now there
are no computations at all.
Thanks for your interest. In my classes, I encourage questions, since
others may benefit. Your opinion may well be shared.
Jim Wilson
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