NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Ducruy Jacques
Date: 2015 Sep 16, 12:57 -0700
Hi Paul,
Thank you for your answer.
Dont forget that the Sumner method and sight time method are the same base : the calculation of the hour angle. In the book of G W Mixter (Primer of navigation), he explain that the time sight was "the standard method for longitude of the old navigation and continues to be widely used in merchant marine. The body should be observed when near E or W". But if the DR latitude is uncertain, and the azimuth different of E or W, the only alternative is the method of Sumner(or the method of Pagel and Johnson).
But it is intesting to note that, if my interpretation is correct, with the table HO 203, you choose a latitude, compute a longitude, so, you have a assumed position : then, with a "pseudo-intercept" (true altitude - tabulated altitude), you draw the LOP ... as St Hilaire method ! But you must no observed the body if it is near of the meridian.
I am of course interested by your comparison between HO 203 and HO 214.
Best Regards
Jacques
