NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: No sextant, no watch, no almanach, nothing
From: Frank Reed CT
Date: 2004 Nov 7, 22:46 EST
From: Frank Reed CT
Date: 2004 Nov 7, 22:46 EST
Geoffrey K wrote:
"The idea was to sail North/South until certain stars passed over the zenith
and then turn East/West to sail along a line of latitude. The time of the
journey was carefully chosen so that the selected stars would be at the
zenith at the correct times in the journey for the East/West turnings, that
is when his boat was estimated to reach the desired latitudes for the turn
East (or West) to run along a line of latitude."
I don't think the time of the journey matters more than getting it right to the nearest six months. For example, let's suppose I'm using delta Orionis (the "upper right" star in Orion's belt) to find zero degrees latitude. I can do that as long as I'm travelling during that portion of the year when Orion transits the meridian in darkness. If upper right corner of the belt of Orion passes straight overhead, I must be on the equator.
This technique is very practical and has certainly been used historically. Note though that it *assumes* that we have no means of finding longitude. We're only finding half of the position using the stars...
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
"The idea was to sail North/South until certain stars passed over the zenith
and then turn East/West to sail along a line of latitude. The time of the
journey was carefully chosen so that the selected stars would be at the
zenith at the correct times in the journey for the East/West turnings, that
is when his boat was estimated to reach the desired latitudes for the turn
East (or West) to run along a line of latitude."
I don't think the time of the journey matters more than getting it right to the nearest six months. For example, let's suppose I'm using delta Orionis (the "upper right" star in Orion's belt) to find zero degrees latitude. I can do that as long as I'm travelling during that portion of the year when Orion transits the meridian in darkness. If upper right corner of the belt of Orion passes straight overhead, I must be on the equator.
This technique is very practical and has certainly been used historically. Note though that it *assumes* that we have no means of finding longitude. We're only finding half of the position using the stars...
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
