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Ted
 
Posts: n/a
Default AIS ship data: everibody have seen this? - why do we use GPS to track buoys??


"Jack Erbes" wrote in message
...
Ted wrote:

snip
Now that we have GPS, why are buoys needed anymore? Aren't you really
interested in where the channel is located and not the location of some
buoy that also happens to be trying to show you where the channel is
located? When did buoys become a destination in and of themselves instead
of merely a source of nautical information guiding us around underwater
obstructions?


Ted,

Let me ask, have you ever actually spent any time doing coastal
navigation? And if so, what navigation resources were available to you
and which ones did you use?


I used pilotage until GPS came along - a map and compass and dead reckoning
with an occasional reference to a landmark on shore confirmed my position. I
use range lights and my depth sounder to verify my location in the channel.

See figure 13-10 on the following link.

http://www.uscg.mil/hq/g-o/cgaux/Pub...tcrew/ch13.pdf

I have a directional antenna to track the Coast Guard's medium frequency
radiobeacons but have never needed to use it - never got lost.

http://www.navcen.uscg.gov/ftp/RADIONAV/rbeacon.txt

One can also track AM radio broadcast stations with this device if needed.

When offshore, if you are able to remember which ocean you are in, then its
not very difficult to know what direction on the compass land can be found.
I measure distance in gallons of fuel. While heading offshore, when one
third of my fuel supply is exhausted then I'm as far out to sea as is
allowed by the skipper (me). After GPS, my map and compass stay in my
emergency kit. They haven't seen the light of day in years. I have only lost
the GPS signal in two places on earth - north of the royal observatory in
Greenwich England and in the harbor west of Naples Italy.

Years ago, before GPS, a friend of mine returning from sea had an unexpected
magnetic source on his boat that affected his compass and took him fifty
miles off course. This "compass failure" almost ran him out of fuel before
he reached shore. I don't put much faith in the cry of the geezers about the
undisputed reliability of the simple magnetic compass and the paper map. I
don't believe that most of them even go boating. They just sit on the
internet and run their mouth.