NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Chronometer Suggestions
From: Dan Allen
Date: 2009 Jan 11, 21:41 -0700
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From: Dan Allen
Date: 2009 Jan 11, 21:41 -0700
On Mon, Jan 5, 2009 at 12:35 AM, bruce hamilton <bruce.hamilton@shaw.ca> wrote:
I presently use the radio time signals or the internet to check or sync
my cheap quartz wristwatch for navigation calculations, and I also have
a cheap watch that picks up WWV when it is in the mood. I find my
trusty Timex is off about 6 seconds a month, but I was wondering if
there are any reasonably priced real quartz chronometers (non-wrist)
that anyone would recommend? I use the word real since the word
chronometer is tossed about by the marketing people without any regard
to it's strict real meaning, which has been posed here at least once.
I would be happy with a settable second hand and some sort of
temperature compensation.
If you can find the right models of Omega or Seiko watches, they make watches that can be accurate in the 10 to 20 seconds a YEAR range. I got a Seiko for $200, an Omega for $900. The Seiko uses quadruple oversampling. The Omega has built-in thermal compensation. Keeping them at a constant temperature helps accuracy.
No matter what you use, it is important to measure them and keep a log. I have an Excel spreadsheet where I note if I have used them a lot or whether they have been sitting on a shelf. I sync them to GPS several times a year and note the discrepancies.
The hardest part in all of this is finding out what kind of movements these watches have. It is easy to find two watches from one manufacturer that are close to the same price and one will have a very average movement (32K quartz rate, no thermal compensation, 30 seconds of error a month) and the other will have much better technology and be highly accurate (10-20 seconds a year) and most of the time nobody knows the difference, and the manufacturers rarely advertise these things. It is quite frustrating.
Dan
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Navigation List archive: www.fer3.com/arc
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