NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Accuracy of Altitude sighting at Sea
From: Geoffrey Kolbe
Date: 1999 Oct 23, 2:37 AM
From: Geoffrey Kolbe
Date: 1999 Oct 23, 2:37 AM
Thankyou to everyone who replied to this question. The consensus seems to be that the standard deviation of an altitude sighting at sea is, at best, about two minutes. Put another way, when a line of position is drawn on a chart as a result of a sighting, the experienced navigator will actually treat this as a "band of position" about 4 miles wide, and would expect his vessel to be somewhere on that band. I have to say, I was a little surprised at this. It means that one is hardly justified in buying a C.Plath Navistar sextant, when for a 50th of the price one can buy a Davis Mk 3 plastic sextant and not really be compromised by its comparative crudeness and simplicity! I read recently that the US Naval Academy has now stopped teaching Celestial Navigation, much to the relief of the cadets who found this to be the hardest subject, along with electrical engineering! However I was surprised when reading the piece that when they had done Celestial Navigation, the acceptance level of skill was that the cadet should be able to find his position to within 3 miles. However, this seems to be quite in accord with the consensus of this list. Thanks again, Geoffrey Kolbe.
