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: Greg Rudzinski
Date: 2008 Jul 14, 15:20 -0700
From: Greg Rudzinski
Date: 2008 Jul 14, 15:20 -0700
Reflecting on my years at sea, I would have to say that from the bridge a L.O.P. intercept of more than three miles from a GPS or LORAN A.P. would send me straight to the short wave for a time check followed by a double check of the index error. Height of eye wasn't easily checked underway. Today the underway height of eye can be checked with a laser rangefinder. The last check would be almanac and sight reduction calculations. Often everything would checkout good which would put blame squarely on my ability to keep the sextant perpendicular to the horizon. On a sailboat beating to weather keeping the sextant perpendicular to the horizon is problematic. Developing a good pair of sea legs is the remedy.G On Jul 11, 8:52�pm, Anabasi...@aol.com wrote: > In general, a merchant ship has from about 20-40 meters of height of �eye > from the bridge. �On a 100 meter vessel, it is a bit lower, with �most larger > ships around 30 meters. > > 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. > > I don't envy those who need to shoot from small vessels. �I have never �done > so, and can't say that I'd like to. �My worse conditions are 20 degree �rolls > with periods of 10-15 seconds. �That can get irritating, but not � > insurmountable. > > Jeremy > > **************Get the scoop on last night's hottest shows and the live music > scene in your area - Check out TourTracker.com! � � � > (http://www.tourtracker.com?NCID=aolmus00050000000112) --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---