NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: How Many Chronometers?
From: Brad Morris
Date: 2009 May 6, 13:22 -0400
From: Brad Morris
Date: 2009 May 6, 13:22 -0400
This is an interesting question. If you know your latitude and longitude, then you can fit your chronometer to the known altitude. If the altitude is wrong for the time, then you can adjust the chronometer error as a function of the longitude you find. A lunar observation can be solved, with a known position, to adjust the chronometer error. In fact, for a known position, many different observations can be used. The only requirement is that time is parameter when solving for a known position. Apparent time at sea may be found by Von Littrow, Bowditch and others, but I do not believe this recovers GMT or UT. But your question is, I think, recovering time when at sea, using only chronometers. I have read about expeditions that kept as many as 22 chronometers, when on survey expeditions (the name escapes me). In this circumstance, voting will permit the accurate recovery. Best Regards Brad -----Original Message----- From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Greg Rudzinski Sent: Wednesday, May 06, 2009 1:11 PM To: NavList Subject: [NavList 8157] How Many Chronometers? When a time tick or other master reference is not available then by what means can a navigator at sea use to determine whether a chronometer is maintaining a consistent rate. If two chronometers are carried then an inconsistency between the two would suggest a problem but then which chronometer is at fault? How about a third chronometer to help the navigator determine which chronometer is behaving badly. Carrying three chronometers does triple the chances of one going down but since quartz watches are cheap why not carry three? Greg "Confidentiality and Privilege Notice The information transmitted by this electronic mail (and any attachments) is being sent by or on behalf of Tactronics; it is intended for the exclusive use of the addressee named above and may constitute information that is privileged or confidential or otherwise legally exempt from disclosure. If you are not the addressee or an employee or agent responsible for delivering this message to same, you are not authorized to retain, read, copy or disseminate this electronic mail (or any attachments) or any part thereof. If you have received this electronic mail (and any attachments) in error, please call us immediately and send written confirmation that same has been deleted from your system. Thank you." --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---