NavList:

Jeremy,

From my mail [NavList 3693]:

Bowditch use for the calculation of the meridional parts two concepts that are based in none model:

a = 21600.0/(2.0*PI)  is used in the spherical model of The Earth

f  = 1.0/298.26       is used in WGS72, but this use a = 6378135.0/1852.0

Also there is some confusion in commercial Route planners use different kind of sailings:

-       OziExplorer – Great circle and great ellipse
-       C-MAP - PC Planner V 11.0.0 – Middle-Latitude Sailing , wrong for long routes
-       MapTech OffShore Navigator – Mercator sailing or loxodromic, WGS84?

Andrés

De: NavList@fer3.com [mailto:NavList@fer3.com] En nombre de Anabasis75@aol.com
Enviado el: viernes, 11 de julio de 2008 17:46
Para: NavList@fer3.com
Asunto: [NavList 5801] Re: Noon sight for longitude

Andrés:

I am advised that the current Bowditch has many more errors. I quoted
from the 1952 edition, where the limits are stated as, "for a stationary
observer," and "if there has been no change in declination." I advise my
students to use an older edition of Bowditch.

Jim Wilson

NavList 5800] Re: Noon sight for longitude

 

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Except for some information on the electronic navigation systems, modern editions of Bowditch, starting with the 1995 edition, have been generally inferior in most respects.  My favorite edition is 1985 Vol I, 1981 edition Volume II.  One small note, the more modern Meridional parts tables are slightly different and more accurate, but I don't think it matters all that much.

 

Jeremy

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