A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding
From: David C
Date: 2017 Sep 14, 01:42 -0700
In the 18th century a departing ship would need to have almanacs for several years in advance.
At the end of the cell nav era commercial voyages were much shorter (than in the 18th century) so the current and maybe the following year were all that was required.
In the 21st century a pdf can be downloaded whenever an internet connection is available.
I believe that early almanacs gave the sun's RA, dec and EOT once per day (I stand to be corrected). In the early 1950s GHA and dec were tabulated for every hour. That is 24 times as much work for a document that was still being produced by human computers, albeit with the assistance of mechanical tabulating machines. In the 21st century anyone who wants the data more that a year or two in advance can probably generate it with an app on their phone, so why should the publishers put in any more effort than they do at the moment?
This opens up a discussion on the history of the almanacs. I a looking forward to the contributions of the experts.......................