A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2021 Jun 2, 18:57 -0700
OK, Steve, I'll get you started with a pair of Sun sights. For both sights you can assume a height of eye of 10 feet and zero index correction.
It is 12 August 2021, and you are sailing towards Hope Town, Bahamas from the east aboard the SS Lollipop. She's a good ship. Your course is 268° T and your speed is 7.1 knots. Your best estimate position (call it DR, if you like) at 14:00 UT is 26°45'N, 76°15'W.
At 14:18:56 UT you shoot the Sun (around 99.9% of Sun shots are Lower Limb, so unless someone goes out of their way to say "UL" then it's LL), and you get a raw sextant altitude of 48°12'. You note that the Sun is about a compass point to the right of dead astern when you take the sight. Work up a line of position for this sight. From that line of position, estimate how many hours you have until you reach Hope Town.
Two hour later you shoot the Sun again. It's 16:19:00 UT and the raw altitude is now 72°46'. By visual estimate, the Sun has moved about 30° to the right (towards south) from the previous sight, so this should give you a reasonable "cut" with the first line of position. Work up another line of position from that sight. If you're ready to try a running fix, combine those two sights to get your fix for 16:19 UT.
Next up: maybe someone could provide a set of twilight star sights from earlier that morning. And maybe a Noon Sun sight to continue this day.