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    Re: Radio Synchronized Clock
    From: Herbert Prinz
    Date: 2002 Mar 5, 22:17 +0000

    Brian Whatcott asked:
    "Has anybody sailed with one of these devices?"
    I have.
    A few years ago (1998?), I tested a clock sold by RadioShack under their own
    brand name (part no 63-970) on a passage from St. Thomas to New York. The model
    runs on 2 AAA batteries, has an external antenna connected via a 3 ft cable. I
    has an indicator showing whether a synchronization signal was received during
    the last 24 hours.
    Here is what I darkly remember about it:
    The clock worked on land in St. Thomas. (I do not know where the nearest WWVB
    transmitter is located.) In the boat, I kept the clock with antenna on a shelf
    in the foccsle. There, it would normally not find the resync signal at night,
    but it would duly indicate that fact. On the first few days out, before I
    wanted to use the clock, I would first take out the batteries and re-insert
    them in order to enforce synchronisation. For this I had to hold the antenna
    out of the hatch or at least close to it. The 3 ft run for the antenna cable is
    to short to be able to mount the antenna outside and the clock inside in a
    convenient location. After 10 to 15 minutes I would have a synchronized time
    signal as well as a stiff arm. After three or four days out, I lost interest in
    the experiment. If there is no WWVB transmitter near St. Thomas (Puerto Rico?),
    I must have received the signal from the US mainland all the time and we may
    safely assume that the clock would have worked all the way.
    The clock has been sitting on a window sill in my house in Connecticut ever
    since and works like a charm. It resynchronizes every night. On the boat
    though, I find other methods more practical.
    Last year, a reputable American instrument maker included a radio based ship
    clock in their catalogue. So I checked it out. This one, unfortunately, like
    many similar products on the market, turned out to be a mere gimmick: It has no
    external antenna and no indicator of signal reception. From a professional
    radio clock, I must demand both. The fact is, a radio clock that does not show
    when it received the last sync signal is not only totally worthless, it's even
    dangerous. The watch error of a conventional clock may be big, but it is known;
    that of an unsynchronized radio clock is totally unpredictable.
    Here are my minimum specs for a radio based ship clock:
    Splash proof.
    Connection to 12V ship power; lithium backup battery.
    Signal reception indicator.
    External button to enforce re-synchronization.
    Choice of display in UT or any other time zone.
    Adjustable display illumination.
    Price under $99.90
    Does it exist? Of course, it does. It's called GPS.
    Herbert Prinz

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