NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Compass Checks at Sea
From: Greg R_
Date: 2008 May 21, 15:41 -0700
From: Greg R_
Date: 2008 May 21, 15:41 -0700
I was looking at the ASA Celestial Navigation Standard (107) the other day, and noticed that one of their requirements is "Calculate the true bearing of a low altitude celestial body in order to determine the error and deviation of the compass". http://www.asa.com/asa_standards/standard_celestial_navigation.html Back in the dark ages when I was first learning celnav, the textbook method for doing compass checks at sea was with amplitude tables and the sun low on the horizon (at least if I remember right). I haven't seen amplitude tables in years (does Reed's still have them?) - but it dawned on me that when you do sight reductions you also have a true bearing for the celestial object (Zn), so why not just momentarily point the bow in that direction and note what the compass reads? Even easier, if you're doing a LAN shot the sun will be either directly north or directly south of the boat for the time that it "hangs" in the sky, so that really simplifies the calculations. Can anyone think of a reason why that wouldn't work as well as using amplitude tables, or is my info on that method several years out of date and nobody does it that way any longer? -- GregR --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---