NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: How accurate are fixes in practice?
From: Frank Reed
Date: 2008 Jul 13, 14:34 -0400
From: Frank Reed
Date: 2008 Jul 13, 14:34 -0400
Jeremy, you wrote: "My normal Celnav fixes are usually within 3 nm and I am disappointed by worse results. Sunlines are usually within 1 nm when I use the GPS fix as the AP, as are LAN observations." From anecdotal evidence consisting of conversations with ocean navigators, this appears to be about normal for observations under "good conditions" with a good metal sextant and no shortcuts in sight reductions. The standard deviation error in individual sights (judging from the offset of LOPs from a GPS position) appears to be roughly 1 minute of arc, implying that about two-thirds of LOPs are within 1 nautical mile. The distribution appears to have some "kurtosis" meaning that there's more likelihood of larger errors than a plain normal (Gaussian) distribution would imply, but it's manageable. So what are "good conditions"? -FER --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
