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Gary
 
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Default RDF (radio direction finding) ... do you ?

otnmbrd wrote:
Wayne.B wrote in
news

On Mon, 06 Mar 2006 05:01:05 GMT, otnmbrd
wrote:


Gee, I wonder how I navigated all over the world, offshore, prior to
GPS, if I had no viable alternative to GPS.


Probably celestial and DR unless you were lucky enough to be on a ship
with a good inertial system.

Tell us about the times when you couldn't get a celestial fix because
of clouds.




First off remember..... you're offshore. Although it's great to know
exactly where you are at all times, for much of your trip it's not really
necessary and even when things were great for celestial you only got three
"exact" fixes every day ... morning/evening stars and noon.
Sure there are times when you don't get a fix for extended periods and
anyone can tell of cases where this caused a grounding, etc., but for the
most part you were and are able to use your knowledge of your boat's
reaction to weather, known currents, etc. to maintain a reasonable DR until
you do get a sight, come on soundings, approach land, etc.
You use whatever is there.
The problem with the sole reliance on GPS or multiple GPS is that you
become a "mechanical" navigator and either forget how to use other methods
or never learn them to begin with, which can rear up and bite you on the
butt when the bananas hit the fan.

otn

Although a yachtie or freighter may not have cared where they were all
the time, that was not everyone's attitude. Take a military example
where you have to rendezvous with another ship or submarine in mid
ocean. A few miles could mean disaster. Take the search and rescue
problem. Same thing. What about the research done on specific things
on the bottom? GPS has facilitated accurate navigation to a degree that
was only dreamed of in the past. It should be your first line piece of
kit when offshore, not at the exculsion of anything else but certainly
head and shoulders above all the rest.
In my opinion the only better way to navigate is by visual fix or radar
fix. Even then I check the fixes against GPS.

Gaz