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    Re: How Many Chronometers?
    From: Lu Abel
    Date: 2009 Sep 22, 12:46 -0700

    
    NavList@fer3.com wrote:
    > Hello from a frequent reader, but not a member of the list.
    >
    > ... As an experiment on one of the ships, we rated our two dozen watches 
    instead of resetting to NAVSAT time.  The purpose was to compare watch brands 
    and purchase price.  We found the mid-priced watches of two particular brands 
    did as good as the expensive watches and all were much more consistent than 
    the ship's chronometers as long as we wore the watch. 
    I had a friend who bought a Rolex.   Turned out it was a terrible 
    time-keeper.   She brought it back to the dealer who said "sorry, it 
    meets specs."   Rolex heavily advertises that its watches are 
    "chronometers."   Turns out that their spec (see 
    http://en.wikipedia.org/wiki/COSC ) allows for a daily rate of -4/+6 
    seconds/day -- that's as much as 2-1/2 minutes per month!!  (Wasn't the 
    Longitude Board's spec 1 minute per month?)   Worse, a rate change of 
    -6/+8 seconds is allowed between horizontal and vertical positions of 
    the watch!   How many of us would keep our hands in a constant position 
    to avoid this allowed rate variation?
    
    In 1970 I bought a Seiko watch (obviously mechanical, given the date of 
    purchase) for under $50.   It was an incredible timekeeper, rate was 
    under 5 seconds per month.
    
    So, yeah, high price seems to buy advertising, not accuracy...
    
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