Doug,
In addition to the comments by Bill (re. the degrading of civilian GPS
signals by DOD at various times), I would add that you should be certain
that your GPS is using the same Datum as your chart. There is a notation on
the chart stating the Datum (i.e.. NAD 83 or WGS 84). There is also a list
of Datums to select from in your GPS (in my Garmin 48 it's on the Navigation
Setup page). If the Datums don't match you won't be able to translate your
GPS position to your chart or vice versa. I believe it is most likely the
workings of the Dept. of Defense. I have seen them turn off some satellites
completely from time to time which is extremely frustrating when you are
using GPS for survey work!!! Don't ever bet your life that the GPS is right,
always verify your position by some other method if possible. If you are
unable to verify then sail with increased caution.
"This new ship here is fitted according to the reported increase of
knowledge
among mankind. Namely, she is cumbered end to end, with bells and trumpets
and clock and wires, ... she can call voices out of the air of the waters to
con the ship while her crew sleep. But sleep Thou lightly. It has not yet
been told to me that the Sea has ceased to be the Sea."
-- Rudyard Kipling
Fair Winds
Mark Dvorscak
M17 #400
GRACE
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