NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re:Observations with pocket sextant in the Baltic
From: Bill B
Date: 2006 Jul 10, 16:30 -0500
From: Bill B
Date: 2006 Jul 10, 16:30 -0500
Alex Back to Lake Michigan/Michigan City for the weekend. Saturday had very little air and even that was dying (big dome of high pressure moving through) while Hammond was seeing 10-15 kt and 15-20 kt up north. The high clouds overhead came in every possible form and were spectacular, better than text-book ideal. A great day to tie a line to a seat cushion, stream it off the stern and float along behind the boat looking at the clouds. I wish I had a camera with me. On the downside, between glare off the 1-2 ft swells and almost glass-like surface, and the following cloud cover, the horizon was almost indistinguishable under the sun (approx 48d elevation). The north and east horizon were very sharp, so I did a ton of IE checks using the natural horizon and a smoke stack 5 nm away. They did not agree with sun IE checks, but more on that in another post. I did 4 observations, although I did not expect much as it was almost impossible to distinguish the horizon through a scope. I was pleasantly surprised with the average (using horizon instead of sun IC), although the SD was well below my norm so that disappointed me. And my first set of observations trending toward over shots ever! Error #1 1.0' #2 0.7' #3 0.4' #4 -1.2' Hot, biting flies, and lower clouds starting to arrive blocking the sun 40% of the time, so went swimming. AVG 0.225' SD 0.98' I did go back to a set 2 weeks earlier, using the natural horizon IC instead of the sun-derived IC, and AVG was reduced to -0.5' off, SD still 0.5'. For the record, sun-derived IC (left eye, sextant vertical is 0.4' +/- 0.1', horizon IC -0.1 +/- 0.1' Needless to say, there are some target/shades/eyeball vs IE issues that have me scratching my head Bill --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---