[PUP] AIS and other gadgets

[John Harris]

Bob commented inthe above thread on the reliability of GPS.

I have a Northstar GPS that has always worked well EXCEPT for one occasion. 
I was north of the eastern portion of Sicily near Vulcano Island searching 
for an appropriate anchoring site. Suddenly (>5 seconds) the location of my 
boat on the chart plotter moved sideways about 1/2 mile.  About 1 minute 
later it moved sideways again about 1/2 mile and was now showing on land and 
traveling inland.

I stopped, started up my backup GPS and compared LAT / LON the ships GPS was 
off by about 1 mile but still acting like it knew where it was with proper 
speed and heading data.

I turned off the ships GPS and restarted it. It came back with all the 
errors corrected.

The purpose of the story is only to emphasis that sometimes the GPS is 
WRONG.

Sail safely,  John Harris
World Odd @ Sea