A good reminder: GPS is not 100%!

[sneuman]

Sun's String of Fury Continues as 7th Major Flare Erupts
By Robert Roy Britt
Senior Science Writer
posted: 09 September 2005
10:33 pm ET


Updated 12:36 p.m. ET Sept. 11

An ongoing series of seven major solar flares, including two on Saturday, could disrupt communications on Earth and generate colorful sky shows for people at high northern latitudes for the next several days.

Already satellites have been affected. Even more serious effects are possible this week.

....

The SEC has reported that agencies have experienced problems with fluctuations in their
electric power systems due to the severe levels of geomagnetic activity. Spacecraft operations, high-frequency communications, and navigation systems such as the Global Positioning System (GPS) constellation of satellites "are also experiencing impacts due to the strong to severe solar activity."

[GordMay]

Checking the GPS ~ by Walt Paul for the CCA (2003)
http://www.cruisingclub.org/communic...ion25Mar03.pdf

and

USCG Safety Alerts: http://www.uscg.mil/hq/g-m/moa/safea.htm
Vessel operators and mariners are encouraged to review the following material. These alerts and lessons learned provide information the Coast Guard believes to be important and deserving of their attention.
~or~
USCG Boating Safety:
http://www.uscgboating.org/

Including:

GPS Caution:
http://www.uscg.mil/hq/g-m/moa/docs/sa0496.htm

GPS Position Offsets + Furuno Update:
On February 4, 2005, the U.S. Coast Guard Office of Investigations and Analysis distributed Safety Alert 1-05 regarding GPS Receiver Position Offset. The manufacturer, Furuno U.S.A. Inc. has provided additional information describing the position offset problem and the availability of a software update.
http://www.uscg.mil/hq/g-m/moa/docs/1-05.pdf