Gary wrote in
news:uTiQf.133119$B94.26881@pd7tw3no:

Comments interspersed:

Although a yachtie or freighter may not have cared where they were all
the time, that was not everyone's attitude.

Wrong. A "yachtie or freighter" ALWAYS care where they are at all times.
The difference/arguable point is that precise knowledge to a small
amount of feet or meters is not always important.

Take a military example
where you have to rendezvous with another ship or submarine in mid
ocean. A few miles could mean disaster.

This was done on a regular basis for years prior to GPS....GPS just
makes it easier and to a degree, more positive.

Take the search and rescue
problem. Same thing.

See above, but frequently the GPS saves precious time.

What about the research done on specific things
on the bottom?

I am still amazed by the general accuracy of that research, done prior
to GPS.

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


No one argues the value of GPS. I frequently mention shipboard
procedures, fully realizing that some things acceptable on a ship are
not acceptable on a smaller cruising vessel, since the space available
for backup and more importantly electrical power sources is considerably
different.
Personally, I'm still using GPS as my backup to check my visual/radar
fixes (which I consider to be more "real world" true) until all Charts
have been corrected using GPS/DGPS readings.
The Major point...... NO one systems is perfect. To rely solely on one
system is to invite disaster.


otn

Gary wrote in
news:aKiQf.130233$sa3.77836@pd7tw1no

When you take a bearing using RDF of a coast station that you want to
get to you don't steer the bearing on the RDF. That bearing is called
a
"curve of constant bearing" and is only part of the solution. The
curve of constant bearing can be either north or south of the actual
bearing to the station unless both the ship and the station are either
on the equator or on the same longitude. What you have to apply to
any other bearing to get the Rhumb line is half convergency. That
will give you the course to steer.

The same problem applies when using RDF bearings to plot a fix. Those
are not straight lines from the radio station but curves of constant
bearing and the resolution of the fix becomes a sperical trig problem
unless you use the half convergency tables to correct those bearings.
Of course the closer you are to the radio station the less the
correction.

GPS is better, way better.

Gaz

Jiminy Crickets!!
This has nothing to do with the post you were responding to.
Are you reading some book on RDF or something?
What you are talking about is long distance RDF, not the close inshore
stuff being discussed by others.

otn

Gary wrote in news:hMiQf.133111$B94.131839
@pd7tw3no:

Jeff wrote:


Actually, my recollection of using RDF is that when we approached a
harbor in limited visibility we made sure that the compass bearing was
shifting in the proper direction, to ensure we were on the proper side
of the transmitter.
That is bush league navigation. You should have been applying the half
convergence correction and steering a compass course.

A. There's nothing "bush league" about it. This is good sound navigation
practice involving "Danger bearings".
B. Not approaching a harbor. You are well within the range where
corrections for great circle would not be absolutely or even practically
needed, although other corrections may apply.

Now I'm sure you're reading a book.

otn

Gary wrote in
news:QPsQf.131399$sa3.25214@pd7tw1no:

otnmbrd wrote:


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



No one argues the value of GPS. I frequently mention shipboard
procedures, fully realizing that some things acceptable on a ship are
not acceptable on a smaller cruising vessel, since the space
available for backup and more importantly electrical power sources is
considerably different.
Personally, I'm still using GPS as my backup to check my visual/radar
fixes (which I consider to be more "real world" true) until all
Charts have been corrected using GPS/DGPS readings.
The Major point...... NO one systems is perfect. To rely solely on
one system is to invite disaster.


otn

What did I say?


How you got there is the problem.
You tend to devalue other methods/systems and there usefullness and
importance, whereas I tend to emphasize other systems/methods and there
usefullness and importance to the overall issues of safety.
We may come up with the same or similar conclusions regarding GPS, but
we approach it differently.

otn

Larry wrote in
:

Larry wrote in
:

There's 3 handheld GPSs, not counting what any guests bring, and two
mounted 12V GPSs on Lionheart. There's 4 chart plotters if you count
the Yeoman marking the paper chart from them. I can flip some little
toggle switches in the NMEA network and force GPS data to power the
network if any component, like the multiplexer, should fail. I'd say
we have a fair number of backup systems in case anything short of EMP
from a nuclear strike happens, in which case navigation won't be much
of an issue....



Crap....that isn't the correct number. I forgot to count the GPS
receiver in the 406 Mhz EPIRB in the ditch bag....


Larry, I don't care if you have fifty GPS's and are towing a dingy full of
spare batterries.
If all you know is GPS, then you might's well be some newbie that just
bought his boat last week.

otn

Wayne.B wrote:
On Mon, 06 Mar 2006 01:57:32 GMT, chuck wrote:

Heathkit made a lot of marine RDF units over the years and these are
usually priced reasonably.

Good grief, they should be free.

Quite right, but where would you find the tubes?

Sound card? So now you are relying on Windows? Oh man!

J/K. I'm a ham. I think it's important to realize that in certain
situations, some of your equipment that you rely on, might not be
available. Knowing how to use alternatives is definitely an advantage.


With regards to RDF, you can triangulate, using a compass and accurate
measures of distance in the water. We used to foxhunt unwanted 2 meter
signals this way.

Also, with your RTM, you'd have more luck finding people with FSK or CW
experience out there, than any rare radio mode.

Cheers

On Fri, 10 Mar 2006 22:56:07 -0500, Larry wrote:

No, I don't have an astrolabe aboard, either!

Then how are you going to sail your latitude lines back to Spain?

Larry wrote:
Jeff wrote in :


Ah! So you're claiming that a GPS isn't really a GPS unless it has a
chartplotter, or two. Sorry, I didn't understand. And you know
you're being set because that little picture of a boat keeps drifting
off to one side. This is completely different from using RDF and
compass, where the compass bearing will keep shifting to one side.




Any GPS that has a DISPLAY is, by definition, a chart plotter. I don't
know of a single, cheap, even handheld GPS that doesn't have a plotter I
can put a waypoint into. There's none on the Raymarine Raystar 120, as
it's a feeder GPS for the Seatalk network, which has a display, which is a
chartplotter.....

This is fairly true today, though it wasn't even a few years ago. Not
everyone updates all of their electronics every year. And a two inch
screen is not always that easy to read, so my comment about
understanding x-track still stands. "Spirally in" can happen even
with GPS; in fact that could be how the boat ended up on the Miami jetty.


NO RDF has any kind of a plotter I ever saw. It points to the station on
the null, duhh..

No RDF (certainly not the RayJeff genre) was intended to be an
all-in-one solution like the modern GPS. In fact, none of the
traditional techniques could be used in isolation; they all required
an understanding of multiple methods. RDF only gives an LOP, no one
would simply "home in" on beacon, especially if there's a cross current.

No one would claim to be a competent navigator if all the knew was the
RDF. Nowadays, anyone how has a jetski with a gps claims to be a
"navigator."


Why are we having this stupid troll? RDF is useless, now, a waste of
space. Use it to weight down the trash when you dump it overboard.

I never claimed we should return to the RDF. All I did was point out
the error in your understanding of traditional navigation. Your
"spiral in" comment marks you as a n00b.

Ironically, your lame attempt to trash traditional navigation has
shown the great weakness of GPS: if you were alone at the helm and a
loose wire shut down your gps, you probably wouldn't be able to follow
a compass course!

No, I don't have an astrolabe aboard, either!
What good would that do you? You've probably forgotten how to use a
compass by now!

Larry wrote:
Jeff wrote in
:


So? Of course its bush league navigation! What other type did you
expect from a couple of soggy guys on a 24 foot wooden boat a dozen
miles off the Maine coast on a foggy night, with nothing more than a
compass, a Ray Jeff radio, and an old paper chart, probably issued by
Texaco? (The big step up was the spinning light depth sounder!)




And they should be arrested for stupidity as soon as they hit the dock.


Ah, now you're claiming that it was illegal to cruise the Maine coast
before GPS! You're cracking me up, Larry!