NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sextant accuracy with short distance to horizon
From: Dan Allen
Date: 2001 Jun 21, 9:59 AM
From: Dan Allen
Date: 2001 Jun 21, 9:59 AM
I've spent more time on land standing on 300' cliffs than on boats, hence my remembering 20 miles. I also remember from many years ago driving many times across the Salt Flats of Western Utah: there is a single stretch of road that is 40 miles long, dead straight. I could see the lights of Wendover UT/NV from about 18 miles away when I drove it at night. Dan -----Original Message----- From Navigation Mailing List [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]On Behalf Of Richard B. Emerson Sent: Thursday, June 21, 2001 7:47 AM To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM Subject: Sextant accuracy with short distance to horizon Dan Allen writes: [...] > This led me to think more about possible inaccuracies of using a horizon > that is very close rather than naturally far away. That is, typically you > use a horizon that is at the limit of your vision, perhaps 20 miles away. [...] While you're in Bowditch, check out table 12, "Distance of the Horizon". Assuming you're 6' tall and standing on a deck 4' off the water, for a total height of eye of 10', the horizon is 3.7 miles off. A twenty mile horizon requires a height of eye of something like 300'. And clear air. [grin] Rick S/v One With The Wind, Baba 35
