NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sextant Positions versus Map Datums
From: Rodney Myrvaagnes
Date: 2002 Jan 21, 5:20 AM
From: Rodney Myrvaagnes
Date: 2002 Jan 21, 5:20 AM
Jared, Did you locate the water tower by bearings on the other landmarks? If you describe exactly what you did, someone on the list might be able to locate some of the other 90%. As we saw both on converted charts near NYC and the Corpscan program you used,, the datum difference hardly accounts for any of it. You don't need a pre-WAIS GPS. You can just turn off the WAIS feature if you don't want to use it. Then you will have all 12 channels working normally. Turning it off will increase the area in which the fix wanders but won't change its center as long as SA remains off, so I am not sure what the point would be. On Sun, 20 Jan 2002 23:21:52 -0500, Jared Sherman wrote: >===================================== > >Incidentally--carefully locating the Jones Beach Water Tower on my 1985 NAD27 1:20,000 chart shows it to be located 0.3nm away from the current position of the tower that is given in the http://www.ngs.noaa.gov/cgi-bin/ds_mm.prl reference list. > >So infosofar as that particular area, more than 1/10th of my position error appears to come from the landmarks being shown in the wrong place. 1/10th down, 9/10th's more to go.It will be interesting to take a (pre-WAAS) GPS to the three area benchmarks that are accessible and see how well it compares. Rodney Myrvaagnes J36 Gjo/a "Religious wisdom is to wisdom as military music is to music." "What contemptible scoundrel stole the cork from my lunch?" -- W. C Fields
