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Doug,

I dare say that I am missing something but I have read through your
original message twice and I am in the same position as Bill Noyce. As
best as I can see from your logic, you first determine the time (GMT) of
LAN for your EP, then you observe the Sun's altitude at that time, then
you assume that your observation was taken at LAN and use its time to
determine your longitude. That, however, is circular reasoning and can
never do anything but "confirm" the longitude of your EP, no matter how
erroneous it really is.

If there is more to your method, please explain it.

If there isn't anything more, I would say that the correspondence
between your GPS readings and your "observed" longitudes only
demonstrates that your EPs are very accurate.


Trevor Kenchington


Doug Royer wrote:

> There are many procedures and many ways to accomplish the same goal.In my
> origonal post on this matter I put forward this method as one of the methods
> used.Some list members were horrified.Most times one doesn't use the Noon
> sight to obtain longitude.I wished to show that when needed(deteriorating
> conditions or circumstances)it can be used to give an approximation of
> longitude where only an estimated latitude was calculated.One more tool.
> Sometimes one doesn't have the luxury of turning the ships head from the
> trackline to obtain celestial course lines(as Joel noted)or the time to
> shoot double altitudes or multiple averaging sights.Are there pitfalls
> useing this method?You bet.


--
Trevor J. Kenchington PhD                         Gadus@iStar.ca
Gadus Associates,                                 Office(902) 889-9250
R.R.#1, Musquodoboit Harbour,                     Fax   (902) 889-9251
Nova Scotia  B0J 2L0, CANADA                      Home  (902) 889-3555

                     Science Serving the Fisheries
                      http://home.istar.ca/~gadus

   

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