NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Were Short methods really Short?
From: Stan K
Date: 2016 Aug 4, 09:34 -0400
From: Stan K
Date: 2016 Aug 4, 09:34 -0400
David,
FWIW, the SR Methods tool of Celestial Tools is a convenient way of checking your work for many of the "mainstream" sight reduction methods. From the Celestial Tools Help for this tool:
"a. Purpose: Allows data extracted from the Nautical Almanac (rather than from the built-in medium-precision almanac) to be entered for sight reductions using various methods. ... The methods included are the Law of Cosines (LoC) calculator method, the Nautical Almanac Concise method (NASR), Pub. 249 (formerly H.O. 249, Sight Reduction Tables for Air Navigation, A.P. 3270 in the United Kingdom), Pub. 229 (formerly H.O. 229, Sight Reduction Tables for Marine Navigation, H.D. 486 in the United Kingdom), H.O. 214 (Tables of Computed Altitude and Azimuth), H.O. 211 (Dead Reckoning Altitude and Azimuth Table, Third Edition, known as Ageton, and the Modified H.O. 211 Compact Sight Reduction Table, known as Ageton-Bayless), H.O. 208 (Navigation Tables for Mariners and Aviators, Sixth Edition, known as Dreisonstok), two versions of the S-Table, and the Weems Line of Position Book."
Attached is the latest released version of Celestial Tools, plus programs (similar to the SR Methods tool) for Ageton-Classic and hav-Doniol.
Stan
-----Original Message-----
From: David C <NoReply_DavidC@fer3.com>
To: slk1000 <slk1000@aol.com>
Sent: Wed, Aug 3, 2016 11:44 pm
Subject: [NavList] Re: Were Short methods really Short?
From: David C <NoReply_DavidC@fer3.com>
To: slk1000 <slk1000@aol.com>
Sent: Wed, Aug 3, 2016 11:44 pm
Subject: [NavList] Re: Were Short methods really Short?
Thanks for the replies. It is a very interesting subject.
I will download the Ageton-Classic pdf and give the method a try. I am on the look out for a copy of Dreisenstock (and other tables). I can probably find a pdf online but I would prefer to work from a paper version if I can.
Yesterday I downloaded the 1864 Nautical Almanac and realised that it is probably impossible to replicate the work load of 19th century navigators. The navigator had to deal with Right Ascension and the Equation of Time. In addition the RA was tabulated once per day, unlike the Aeronautical Almanac in which GHA is listed at 10 minute intervals. Also the navigator had to calculate GMT from the rate of the chronometer - a trivial task today with a calculator.
Someone asked why the hav-cos formula replaced the sin/cos formula. My understanding is that it was to avoid having to take logs of negative numbers.
I have just checked the local weather forecast. The sun is likely to be out of commission for the next five days so I will have plenty of time to study the theory (-;
File: 136125.agetonclassic.zip
