NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Non Electronic Sight Reduction
From: Greg Rudzinski
Date: 2009 Dec 13, 18:07 -0800
From: Greg Rudzinski
Date: 2009 Dec 13, 18:07 -0800
Today I was able to work a morning Sun line five different ways using just
tables (Pub. 249, Weems, Dreisonstok, Ageton, and Trig/Log). The LOP results
were all within one nautical mile of each other. The only interpolation done
was for Declination using Pub. 249. One side of one sheet of paper easily
contained all five reductions.
Personal impressions of the various methods
Rank:
1. Pub. 249
2. Weems Line of Position
3. Dreisonstok Pub. 208
4. Ageton Pub. 211
5. Trig/Log Tables
Pub 249 is exceptionally fast to use but is a large table. Intercepts can be
large. Declination limited to 29° on volumes 2 and 3.
Weems and Dreisonstok are very quick with Weems coming out on top with the use
of a graphical solution for determining azimuth.
Ageton involves an extra summing but is a bit more accurate. Intercepts are
short due to using the DR position as the assumed position.
Trig/Log tables involve the most summing and table page turning but still
practical and accurate. Intercepts are short due to using the DR position as
the assumed position. An excellent companion to a calculator or sliderule.
I like all of the above methods and recommend that navigators give each a try
to determine the best clutch of tables to keep on hand. Even though Ageton
Pub. 211 ranks 4th it is stowed in my sextant case because it is thin and
compact.
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