NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Digital Dead Reckoning Calcs
From: David C
Date: 2023 Nov 20, 20:54 -0800
From: David C
Date: 2023 Nov 20, 20:54 -0800
The Middle Latitude gives an approximate result. Middle latitude = (lat1 + lat2)2.
For an excact result use the difference of meridional parts. dmp tables are found in volumes such as Norie.
dep = dlong X d lat / dmp
I recently boasted that I had taken delivery of a copy of the Admiralty Manual of Navigation 1914. This book has a six page chapter called Course and Distance by Calculation. It deals with rumb lines. I do not claim that I understand the chapter.
You are discussing one of a number of "salings" - Great-circle, mercator, middle-latitude, parallell, plane, short distance. I guess that using dmp is a Mercator sailing and middle-latitude is a sailing of that name. but would have to study a book to make sure!!!!!
David C
