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Subject: Re: Meridional Distances
From: Arthur Pearson (arthurpearson@XXX.XXX)
Date: Tue Sep 17 2002 - 19:28:12 EDT
Lest the authors of the Silicon Sea legs think their work unappreciated,
I for one have begun working the legs. I worked the last leg published
primarily using the Traverse Tables in a 1965 version of Bowditch that
give very similar results to the official answers. I note that when I
downloaded the tables from the current version of Bowditch online, the
current configuration if the tables is much less flexible and precise
than the '65 version. Although one has several table lookups to get a
solution, the older tables allow solution of problems <1,000 nm with
ease.
-----Original Message-----
From: Navigation Mailing List
[mailto:NAVIGATION-L@XXX.XXX] On Behalf Of Peter Fogg
Sent: Tuesday, September 17, 2002 6:53 PM
To: NAVIGATION-L@XXX.XXX
Subject: Meridional Distances
Have recently come across a new (to me) method of calculating rhumb line
courses and distances, and also traverse calculations, where the
starting position, course and distance are known, and the finishing
position needs to be calculated.
The method uses not just Meridional Parts, with which I am familiar, but
also Meridional Distances, which are new to me.
Although I have tables accurate to 2 decimal places for the Meridional
Parts, the Meridional Distances come only in whole degrees, so need to
be interpelated for in-between values.
Despite this the method is simple and straight-forward enough, no more
complex or prone to error than alternative methods. I am told it is
particularly accurate, although I don't know if there is any way to
check this. Used on old Silicon Sea problems it gives answers similar
but not identical to the official answers, but then so do other methods
- mostly!
With a new Silicon Sea leg in the offing I intend to post a comparison
of a few different methods (assuming it contains any such problems) and
let others compare the results with their own methods.
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