NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Andrés Ruiz
Date: 2009 Nov 19, 08:29 +0100
Jeremy, I use the same technique for plotting the
LoPs, for the same reasons.
One of my main reasons for start programming the
nautical calculations was in a small sailcraft you are the mariner, the pilot
and the captain, and is very very difficult to do the SR without errors when on
sea.
The other, is very good way to dissect the problem
and learn about it.
Andrés Ruiz
Navigational Algorithms
http://sites.google.com/site/navigationalalgorithms/
De:
Anabasis75@aol.com [mailto:Anabasis75@aol.com]
Enviado el: martes, 17 de
noviembre de 2009 18:05
Para:
Asunto: Re: [NavList 10725] Re: AP
terminology, WAS: 2-Body Fix -- take three
…
Since JK finally
explained what he meant my calculating LOPs "directly" I agree with
him to a point. When using a calculator for my celestial triangle
reductions (which I do for a vast majority of my work at sea if it is not done
on the computer), I certainly could use the DR/GPS fix as the AP for each star
and then calculate and plot each star line from the azimuth and intercept from
this position. The trouble with this in a practical sense is the mess it
makes when plotting manually. I prefer to advance my lines in a way we do
with radar LOP's. I advance or retard each AP and plot from there.
This gives me a clean fix near my track. If I were to try to advance
the DR I would have a mess near my track and might be confused with the
previously plotted LOP's. It is even worse when you plot the original
lines then try to advance them as you cross your track. When my
computer plots this, it is much easier, and I use his "Combined"
method for nearly all of my star fixes.
…
In conclusion, there are
a lot of practical considerations as to why a particular method is used to
determine position at sea that goes far beyond the reduction of the celestial
triangles, especially when you are using more primitive tools.
Jeremy
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