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    Re: Role of CN at sea, was Re: Averaging sights ...
    From: Nels Tomlinson
    Date: 2004 Oct 12, 22:34 -0800

    Well, what I really meant was: has anyone heard of a boat loosing or
    breaking all of its receivers?   At 5 to 10 knots, loosing the signal
    for a quarter hour or so shouldn't be a big deal, but loosing all the
    GPSs to a lightning strike, simple failure  or  some series of
    accidents could be a big deal, and it seems as if it's bound to happen
    sometime.
    
    Nels
    
    
    On Tue, 12 Oct 2004 19:15:25 -0500, Bill  wrote:
    > > Has anyone ever heard of a vessel loosing all of its GPSs while at
    > > sea?  If it hasn't happened yet, I suspect it will.
    >
    > In approx.. 700 hours of land and water operation over the past 3 years, I
    > have experienced five loss-of-satellites-signal situations, usually lasting
    > from 5-15 minutes.  Three were on land, one due to a detour through the
    > mountains in Pennsylvania after a 50 car/truck pile up in front of me.  With
    > mountains on all horizons and a blinding snowstorm overhead, would hardly
    > blame that on the system or unit.
    >
    > The other two land situations I have no explanation for.  Great weather,
    > flatlands, no military bases nearby.
    >
    > Of the two on water (Lake Michigan) all units (my Garmin 76, an older
    > Magellan, and the owners chartplotter) all failed to get adequate signals
    > for 10 minutes or so. Partly cloudy sky.  In one case an older Garmin showed
    > our speed-over-ground on a broad reach in a 34' Catalina as 33.8 kn.  Not
    > too shabby--lucky the rudder stayed attached ;-)
    >
    > I have seen people sit on their unit left on the cockpit cushion and it lost
    > all of its waypoints.  A friend's older Magellan unit failed to find
    > satellites after 3 hours.  It is been replaced by a new unit.  Have also
    > seen two different Loran C units go haywire, with errors of more than 5' lat
    > and lon.
    >
    > In talking with about a dozen sailors on the 600 dock at Michigan City, each
    > and every one of them has experienced unexplainable signal loss of 5-15
    > minutes while on the water.
    >
    > Perhaps the Great Lakes don't meet the definition of "at sea," and is mostly
    > coastal piloting, but there is ample evidence a single unit can malfunction,
    > and even with multiple units, there are periods where signals cannot be
    > received.
    >
    > Not a big deal on the southern half of Lake Michigan where it is pretty much
    > point-and-shoot, but uncomfortable in the area where Michigan, Huron, and
    > Superior merge.
    >
    > Bill
    >
    
    
    

       
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