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    Re: GPS Accuracy Now.
    From: Tony S
    Date: 2000 May 02, 5:49 PM

    But, but, but, Richard ....I _want_ to be able to sail into my slip
    under 0/0 ISR (Instrument Sail Rule) conditions!  :)
    1-3 meters ain't bad, eh?
    We can't stop progress, guy, regardless of "emotions". So many land
    services are setting the pace. We benefit.
    "Richard B. Emerson" wrote:
    > Philip OUVRY writes:
    >  > For maritime users in small craft a GPS accuracy of 100 metres is
    >  > more than sufficient.  Provided you can find the fairway or safe
    >  > water buoy at the approaches to ones destination or the entrance to
    >  > the harbour, it is far safer to navigate by sight (i.e. pilotage)
    >  > rather than by 'head-down' reference to the GPS.
    > Slavish adherence to any one source of navigation information, be it
    > the display of a GPS or the human eye, will sooner or later lead to
    > problems.  The prudent mariner will continually compare one source of
    > information with another to be sure of having reliable information.
    >  > Out at sea an accuracy of one mile is quite sufficient.
    > Er, I'd even argue that three miles is quite enough.
    >  > There are occasions when a greater accuracy would be useful such as
    >  > an anchor position in a crowded anchorage.  There is no real need
    >  > to know the boat's position to an accuracy of 30 metres or less.
    > While perhaps 15 meter accuracy seems superfluous for small boats, one
    > of the more important benefits of SA being disabled is speed accuracy.
    > Remember that every time the satellites danced and, albeit briefly,
    > had 30 foot sailboats moving at 20 or 30 knots, speed averaging and
    > log functions were corrupted by these false motions.  Without SA,
    > speed and distance covered are going to be closer to reality than when
    > SA was enabled.
    > Rick
    > S/V One With The Wind, Baba 35

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