NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Time and cel nav, a stupid question
From: Paul Hirose
Date: 2008 Apr 26, 12:47 -0700
From: Paul Hirose
Date: 2008 Apr 26, 12:47 -0700
Lu Abel wrote: > I've found cheap Timex or equivalent > quartz watches to be remarkably good timekeepers (at least on my wrist, > I've never taken them off and subjected them to freeze-boil cycles) -- > if given the chance to measure watch rate, I'd be pretty confident of > going for a month or even more without cross-checking with WWV or > equivalent. Here are the daily rates of my $25 Timex Expedition for the last year. I actually check it only once per month, and convert the error to the equivalent daily rate for that month. +.43 March 2007 +.41 April +.41 May +.40 June +.35 July +.34 August +.40 September +.45 October +.44 November +.43 December +.42 January 2008 +.42 February +.45 March This watch was bought in 2000. The original battery is still installed, though for about a year it's been so weak that the display goes blank when I press the illumination button. The watch still keeps good time, so I haven't bothered to get the battery changed. There seems to be a remarkably consistent relationship between seasonal temperature changes and watch rate. In the table above, the fastest rates are +.45 in October 2007 and March 2008. The corresponding values a year before were +.43 and +.43. The slowest rates are +.35 and +.34 in July and August, compared to +.26 and +.35 a year before. That +.26 is not a typo. However, it may be significant that the anomalous value occured when I forgot to do my monthly check until the middle of the month. So "June" had 6 weeks and "July" had 2 weeks. I may have made a mistake in my math. The consistent values from May and September tend to confirm that suspicion. The respective rates were +.39 vs. +.41, and +.40 vs. +.40, for 2006 vs. 2007. For the correct time, I call WWV and the USNO on my Nextel cell phone. The delay is about 1/4 second compared to WWV on shortwave radio. It's so consistent that I make no correction for the delay. I used to tune WWV on the shortwave radio for my time reference, but sometimes the propagation was bad on all frequencies. It's less trouble to use a phone. -- I block messages that contain attachments or HTML. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---