NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: mid-longitude sailing
From: Bill B
Date: 2007 Jan 10, 16:44 -0500
From: Bill B
Date: 2007 Jan 10, 16:44 -0500
Bill wrote > I did play with departure > and destination latitudes approaching zero and those seem to be a wee bit > off at first blush. My error. "...latitudes approaching zero..." should read "longitudes approaching zero." Lu wrote: > 2. Any great circle course, when plotted on a Mercator chart, looks a > curve swinging towards the nearest pole and then back down again. The > rate of change of a course is greatest in the higher latitudes. If I > were trying to translate a great circle course into steering directions, > I'd want to calculate course direction more frequently near this > northward (or southward) peak than at lower latitudes. In George's defense, he did note that the one could subdivide a long passage. He stated, "Having the coordinates of that middle-point, you can then easily split each half further, and so on, using the same method, until your point-to point legs are short enough to treat each one as a rhumb-line." Given a programmable calculator or computer, or more time the other formula's are fine. With nothing more than the simple formula George presented and a $10 pocket calculator one can do the job on the fly. Bill --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---