NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Chronometer Suggestions
From: R B Emerson
Date: 2009 Jan 6, 07:12 -0800
From: R B Emerson
Date: 2009 Jan 6, 07:12 -0800
Yewbetcha! At the equator, every minute of error is one nautical mile and that makes a second's error about 100 feet. Given that a really good round of sights at sea might be good to a mile or two, where's the problem? The problem is that these errors can become cumulative. And even if they're not, navigation is all about accuracy; if timing's sloppy, what else might be sloppy, too? Sooner or later, the boat is put at risk because of all the slop. Not Good. (Why "at the equator"? Because the higher the latitude, the smaller the distance covered by a degree of circumference. The nautical mile is derived from the Earth's circumference at the equator divided by 360 degrees. Measure the Earth's circumference at, say, 45N, and the number of miles is less but there are still 360 degrees to that circumferential circle.) Cheers, Rick On Jan 6, 8:05�am, William Sellarwrote: > As a beginning celestial navigator, I am wondering how much time and watch accuracy is actually required for practical navigation.� Can we predict how many miles off one would be for every second of time error? > � > Bill --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---