NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Degrees and minutes vs decimal degrees and the Daily Pages
From: Stan K
Date: 2015 Oct 17, 14:04 -0400
FYI, there are plenty, well, at least several, sextants out there that use seconds on the vernier scales of their micrometer drums rather than tenths of minutes. One example is the Husun sextant in the attached photo (from Bill Morris's sextantbook.com site). Sure, the seconds will eventually get converted to minutes for use with the Almanac, but some sextants do not do this conversion "on the sextant dial". When I was writing the DOS predecessor to Celestial Tools, we had a couple of these sextants, so I included the ability to enter sextant altitude and index error as DM.m or DMS, which continued with Celestial Tools.
From: Stan K
Date: 2015 Oct 17, 14:04 -0400
John,
You said, "Note that no navigator uses seconds - they are converted into decimal minutes in the NA and on the sextant dial."
Stan
-----Original Message-----
From: John D. Howard <NoReply_Howard@fer3.com>
To: slk1000 <slk1000@aol.com>
Sent: Sat, Oct 17, 2015 12:11 pm
Subject: [NavList] Re: Degrees and minutes vs decimal degrees and the Daily Pages
From: John D. Howard <NoReply_Howard@fer3.com>
To: slk1000 <slk1000@aol.com>
Sent: Sat, Oct 17, 2015 12:11 pm
Subject: [NavList] Re: Degrees and minutes vs decimal degrees and the Daily Pages
Steve,
There is no difference. People ( navigators ) like minutes because one minute is one nautical mile. Thats it.
Note that no navigator uses seconds - they are converted into decimal minutes in the NA and on the sextant dial. Different groups of folk use different units because they are convient, not because there are more accurate, The US Army uses mils when firing their big guns, computer geeks use radians to compute, etc. etc.
I write my own computer programs to do nav and always use decimal degrees. When I get an answer I either drop off the decimal part - azimuth - or multiply by sixty to get miles. No sweat because I use a calculator. If I was on a sailing ship in the 19th. C. then that one multiplaction would be enough to make me use degrees and minutes.
Call it tradition. John H.
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