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

On Fri, 03 Mar 2006 23:11:04 -0500, Wayne.B
wrote:

The best backup for GPS is another GPS, and
some spare batteries.

Agreed. I have two, Old Handheld and Older Handheld, plus Really Old
AlphaNumeric Trimble Unit on the Nav Station that is the Most Accurate
of All.

But I also know coastal pliotage and carry a sextant, because things
get dropped, batteries fail and GW Bush can turn GPS off if the
terrorists are winning, or if he feels like it. (Doesn't matter once
Galileo's operational, I suppose, but that's another story).

So as long as I can see the shore, hear the surf, smell the land and
persist in carrying paper charts, odds are good that I'm covered.

I find that the GPS is handy in CONFIRMING my location (as far as that
goes), but navigating with it is strictly optional. It's an aid, one
of many, not a final arbitor or a second skipper.

R.

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

Courtney Thomas wrote:
Jeff wrote:

Gary wrote:

otnmbrd wrote:

That same bolt of lightening will take out your calculator so you
then have to work stars long hand. It'll also kill your digital
watch and radio so you won't have the correct time. It'll probably
short out your boat so you won't be able to work the stars out
until light the next morning. The lightening excuse to learn astro
is BS. Learn it because you want to or take a couple extra
handheld GPS. Practice dead reckoning. Know where you are all the
time.

Gaz





Let's see...... calculator gone, long hand star calc's....add a
minute or two to the solution.
digital watch killed..... in that case I'm probably dead too so
what do I care.... always have a mechanical clock that you know the
error...no big deal, was done for years.
lights out?....lite a candle or wait till daylight.... what the
hell, it's offshore navigation, what's the rush....



And how did you check the error on that deck watch? Radio? What was
the error and how much does it change daily? Can't just do the time
check anymore. Damn lightening.



With all due respect Gary, I think you need a refresher course on
celestial. I wear a "windup" watch, and have two windup ship's
clocks. All of them are accurate to a minute a month, and have a
pretty consistent error rate. I generally set them once a week, so the
error is well under a minute. So, would you care to tell us what the
expected error would be for both Latitude and Longitude?

To be honest, I don't really buy the lightning argument either. But
I'm not sure some find fault in celestial because it is not accurate
to 3 meters.


Jeff,

I'd be very interested in your opinion of where to get an inexpensive
but reliable "windup" clock/watch ?


Did I say inexpensive? My watch is an older Rolex, and the clocks are
both Chelsea. The most accurate of the three is a WWII deck clock I got
for about $250. My point is not that windup watches/clocks are perfect
backups for their more modern counterparts, but that in a pinch
electronics are not necessary for navigation. Latitude can be
determined without time, and longitude can be determined within 30 miles
even with a few minutes error. Not great for long passages, but good
enough to get you home.

BTW, my father-in-law spent 17 days in a lifeboat at the end of WWII.
He was able to navigate about 1000 miles using a Movado watch.

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

I don't know who you are or what you do...

Da Kine... Trust me. Mr. Gary Davis is very well qualified as a
commentator on this news group. Refer to the following URL:

http://www.navy.forces.gc.ca/oriole/...mandteam_e.asp

Best regards

Bill

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

Well, it should still work as a receiver, anyway.

Terry K

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

On 6 Mar 2006 20:20:24 -0800, "purple_stars"
wrote:

snipity-snip

RDF might be fun to play around with out in the deep blue.

Correct me if I'm wrong, but don't radio waves travel in great
circles? If so it might be fun working the great circles out in
conjunction with your RDF fixes.
Just a thought.
Mark E. Williams

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

On Wed, 08 Mar 2006 17:54:51 -0600, Maynard G. Krebbs
wrote:

RDF might be fun to play around with out in the deep blue.

Correct me if I'm wrong, but don't radio waves travel in great
circles? If so it might be fun working the great circles out in
conjunction with your RDF fixes.

The vast majority of RDF fixes are done at ranges of less than 50
miles or so. They become increasingly unreliable as the distance
increases for a variety of reasons. When RDFs were still popular they
were frequently used at ranges of just a few miles to home in on a
breakwater or harbor entrance in the fog.

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

On 8 Mar 2006 15:25:57 -0800, "Terry K" wrote:

Well, it should still work as a receiver, anyway.

True, and they are big enough that it is not likely to get lost or
misplaced. :-)

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

Maynard G. Krebbs wrote in
:

RDF might be fun to play around with out in the deep blue.

Correct me if I'm wrong, but don't radio waves travel in great
circles? If so it might be fun working the great circles out in
conjunction with your RDF fixes.
Just a thought.
Mark E. Williams



RDF is great as long as there is NO DRIFT, water current or wind drift.

If you don't learn to take that into account and just follow the RDF to the
station, you end up in this big spiral to the target, the long way around!

GPS, of course, doesn't suffer these 1930's problems.

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

Larry wrote:
Maynard G. Krebbs wrote in
:


RDF might be fun to play around with out in the deep blue.

Correct me if I'm wrong, but don't radio waves travel in great
circles? If so it might be fun working the great circles out in
conjunction with your RDF fixes.
Just a thought.
Mark E. Williams




RDF is great as long as there is NO DRIFT, water current or wind drift.

If you don't learn to take that into account and just follow the RDF to the
station, you end up in this big spiral to the target, the long way around!

GPS, of course, doesn't suffer these 1930's problems.

I understand one of the problems with RDF in the English Channel was
collisions with the beacon ships. Apparently, because RDF doesn't give
ranges, it is always critical to keep the radio beacon of the light ship
on one bow or the other when in fog!

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

Larry wrote:
....

RDF is great as long as there is NO DRIFT, water current or wind drift.

If you don't learn to take that into account and just follow the RDF to the
station, you end up in this big spiral to the target, the long way around!


The same will happen with a GPS, unless you know how to use cross
track error. And its certainly better than simply following a compass
bearing.

Anyone capable of using RDF would also know how to use a compass, and
understand the meaning of the changing bearing. Today's GPS user
doesn't necessarily have these skills.

GPS, of course, doesn't suffer these 1930's problems.

1930's??? Most boaters couldn't afford Loran until the late 1980's.
And small, waterproof GPS only became available until about 10 years
ago. You sound like a n00b that took his "safe boating class" from
the jetski salesman last weekend.

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

Jeff wrote in :

The same will happen with a GPS, unless you know how to use cross
track error. And its certainly better than simply following a compass
bearing.



It will? How's that? My GPS has a few chart plotters connected to it.
They all have at least one, even without the chart plug. You know where
the waypoint is. It draws a line you follow, even if you're steering it by
hand.

How do you spiral in with this? You might be looking at the wrong display!

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

Larry wrote:
Jeff wrote in :


The same will happen with a GPS, unless you know how to use cross
track error. And its certainly better than simply following a compass
bearing.




It will? How's that? My GPS has a few chart plotters connected to it.
They all have at least one, even without the chart plug. You know where
the waypoint is. It draws a line you follow, even if you're steering it by
hand.

How do you spiral in with this? You might be looking at the wrong display!


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.

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

On Thu, 09 Mar 2006 22:33:00 -0500, Jeff wrote:

Ah! So you're claiming that a GPS isn't really a GPS unless it has a
chartplotter, or two.

Even the simplest handheld will have a cross track error function
these days. Anyone who doesn't know what it is, or how to use it
really does not belong in a situation where navigation is required.

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

Wayne.B wrote:
On Thu, 09 Mar 2006 22:33:00 -0500, Jeff wrote:


Ah! So you're claiming that a GPS isn't really a GPS unless it has a
chartplotter, or two.


Even the simplest handheld will have a cross track error function
these days. Anyone who doesn't know what it is, or how to use it
really does not belong in a situation where navigation is required.

Yes, of course. And now for the third time I'll point out that
noticing the compass bearing of an RDF target change is no more
complex than watching the x-track change.

The ability to connect a GPS to an Autopilot and track a straight line
across a current is real spiffy. Being able to do it manually by
understanding what's going on around you is even better.

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

On Fri, 10 Mar 2006 08:19:30 -0500, Jeff wrote:

Yes, of course. And now for the third time I'll point out that
noticing the compass bearing of an RDF target change is no more
complex than watching the x-track change.

I agree but if you are starting to drift off your track line, you will
usually pick it up on cross track error well before you see a bearing
change of even one degree.

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

Larry wrote:
RDF is great as long as there is NO DRIFT, water current or wind drift.

If you don't learn to take that into account and just follow the RDF to the
station, you end up in this big spiral to the target, the long way around!

GPS, of course, doesn't suffer these 1930's problems.


Well, all it's doing is solving the relative bearing drift
for you. If a person doesn't know how to do this for
themselves, then they can't navigate. Period. It's one of
the basic skills.

Of course, under most circumstances you can let the machine
do it for you. But I'm of the old school that says it's
better to know how, yourself.

Another poster here said, a long time ago: "When people
complain that learning to navigate the old-fashioned way is
difficult, slow, & boring, you can always answer that
crashing your boat into the rocks is easy, fast, and
exciting!" It's the best answer I've heard.

Fresh Breezes- Doug King

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

Wayne.B wrote:
On Fri, 10 Mar 2006 08:19:30 -0500, Jeff wrote:


Yes, of course. And now for the third time I'll point out that
noticing the compass bearing of an RDF target change is no more
complex than watching the x-track change.


I agree but if you are starting to drift off your track line, you will
usually pick it up on cross track error well before you see a bearing
change of even one degree.

Of course. I certainly wouldn't argue that RDF and Compass is more
accurate than GPS with x-track. My point is simply that anyone who
would unknowingly "spiral in" on an RDF target probably couldn't be
trusted to understand a GPS either.

If all you do is blindly minimize x-track you might not appreciate the
nature of the current, and how it's affecting other boats.

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.

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

DSK wrote:
Larry wrote:

RDF is great as long as there is NO DRIFT, water current or wind drift.

If you don't learn to take that into account and just follow the RDF
to the station, you end up in this big spiral to the target, the long
way around!

GPS, of course, doesn't suffer these 1930's problems.


Well, all it's doing is solving the relative bearing drift for you. If a
person doesn't know how to do this for themselves, then they can't
navigate. Period. It's one of the basic skills.

Of course, under most circumstances you can let the machine do it for
you. But I'm of the old school that says it's better to know how, yourself.

Another poster here said, a long time ago: "When people complain that
learning to navigate the old-fashioned way is difficult, slow, & boring,
you can always answer that crashing your boat into the rocks is easy,
fast, and exciting!" It's the best answer I've heard.

Fresh Breezes- Doug King

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

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

Jeff wrote:
Wayne.B wrote:

On Fri, 10 Mar 2006 08:19:30 -0500, Jeff wrote:


Yes, of course. And now for the third time I'll point out that
noticing the compass bearing of an RDF target change is no more
complex than watching the x-track change.


I agree but if you are starting to drift off your track line, you will
usually pick it up on cross track error well before you see a bearing
change of even one degree.


Of course. I certainly wouldn't argue that RDF and Compass is more
accurate than GPS with x-track. My point is simply that anyone who
would unknowingly "spiral in" on an RDF target probably couldn't be
trusted to understand a GPS either.

If all you do is blindly minimize x-track you might not appreciate the
nature of the current, and how it's affecting other boats.

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.

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

otnmbrd wrote:
Wayne.B wrote in
:


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

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

Gary wrote:
Jeff wrote:

Wayne.B wrote:

On Fri, 10 Mar 2006 08:19:30 -0500, Jeff wrote:


Yes, of course. And now for the third time I'll point out that
noticing the compass bearing of an RDF target change is no more
complex than watching the x-track change.


I agree but if you are starting to drift off your track line, you will
usually pick it up on cross track error well before you see a bearing
change of even one degree.



Of course. I certainly wouldn't argue that RDF and Compass is more
accurate than GPS with x-track. My point is simply that anyone who
would unknowingly "spiral in" on an RDF target probably couldn't be
trusted to understand a GPS either.

If all you do is blindly minimize x-track you might not appreciate the
nature of the current, and how it's affecting other boats.

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.

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 of course the helmsman had a compass course to follow. Are you
actually suggesting that the helmsman was sitting there with the RDF
in his hand? That's the way we do it today, where the helmsman is
surrounded by and array of LCD screens, but it was only a few years
ago that even the smallest boat need a separate nav center down below
because none of the instruments were remotely waterproof.

I'm not familiar with the term "half convergence correction," though
I'm guessing its a method of correcting for the difference between
great circle and rhumb line, and thus of little import to entering a
harbor in a small boat. Perhaps you can explain?

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

Jeff wrote:


Yes, of course. And now for the third time I'll point out that
noticing the compass bearing of an RDF target change is no more
complex than watching the x-track change.


I agree but if you are starting to drift off your track line, you will
usually pick it up on cross track error well before you see a bearing
change of even one degree.

Of course. I certainly wouldn't argue that RDF and Compass is more
accurate than GPS with x-track. My point is simply that anyone who
would unknowingly "spiral in" on an RDF target probably couldn't be
trusted to understand a GPS either.

If all you do is blindly minimize x-track you might not appreciate
the nature of the current, and how it's affecting other boats.

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.


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 of course the helmsman had a compass course to follow. Are you
actually suggesting that the helmsman was sitting there with the RDF in
his hand? That's the way we do it today, where the helmsman is
surrounded by and array of LCD screens, but it was only a few years ago
that even the smallest boat need a separate nav center down below
because none of the instruments were remotely waterproof.

I'm not familiar with the term "half convergence correction," though I'm
guessing its a method of correcting for the difference between great
circle and rhumb line, and thus of little import to entering a harbor in
a small boat. Perhaps you can explain?

You didn't explain earlier that you were "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?" Half convergence is not important until you are about 100
miles away from the transmitting station. I am trying to explain the
corrections to RDF when used as a nav tool in slightly different
cicumstances. In your case, half convergence doesn't matter and there
is no way of calculating cross track error unless you know the current
or get proper fixes with the RDF. You certainly won't "spiral in" on a
12 mile track.

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

On Fri, 10 Mar 2006 22:27:04 GMT, Gary wrote:

You certainly won't "spiral in" on a
12 mile track.

Hopefully we all agree on that.

There were a couple of times I was glad to have my old Ray Jeff RDF on
board but I am no more eager to dust it off and use it again, than I
am to do long division by hand.

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

Gary wrote:
....
You didn't explain earlier that you were "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?" Half convergence is not important until you are about 100
miles away from the transmitting station. I am trying to explain the
corrections to RDF when used as a nav tool in slightly different
cicumstances. In your case, half convergence doesn't matter and there
is no way of calculating cross track error unless you know the current
or get proper fixes with the RDF. You certainly won't "spiral in" on a
12 mile track.

Well, I did specify "entering a harbor" and this sub-thread was
triggered by Larry's comment about "spiraling in" in a cross current,
which would not likely be an insurmountable problem for a professional
on a large ship 100 miles off (or even an amateur, back in the day).

The problem of spiraling certainly does happen on short trips.
Consider the crossing from Wood's Hole to Martha's Vineyard, about 3.5
miles across Vineyard Sound, which often has a 2.5 knot current. If
you simply "home in" on the West Chop Lighthouse (or a hypothetical
radiobeacon at that spot) you could find yourself halfway to
Nantucket, downwind, and with a nasty chop in your face. (Don't ask
how I know this ...) This little passage can be particularly
vexatious because there are almost always 2 or 3 ferries crossing,
which are usually pointed one way, but headed another.

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

Wayne.B wrote:
On Fri, 10 Mar 2006 22:27:04 GMT, Gary wrote:


You certainly won't "spiral in" on a
12 mile track.


Hopefully we all agree on that.

What kind of boats do you guys have??? You sound like a powerboater
claiming you don't have to think about currents because you're doing
30 knots all the time.

Where I sail there are frequently currents of 2 knots or more, plenty
to cause "spiral" for a slower sailboat.



There were a couple of times I was glad to have my old Ray Jeff RDF on
board but I am no more eager to dust it off and use it again, than I
am to do long division by hand.


I'm guessing I'm one of the few here that actually remembers how to
take square roots long hand.

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

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.....

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

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.

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

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

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.

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

On Fri, 10 Mar 2006 19:23:54 -0500, Jeff wrote:

What kind of boats do you guys have??? You sound like a powerboater
claiming you don't have to think about currents because you're doing
30 knots all the time.

Where I sail there are frequently currents of 2 knots or more, plenty
to cause "spiral" for a slower sailboat.

You're doing something wrong. Before you start, first solve the
current vector problem using an estimated speed for your boat and the
average current speed/direction from your tide tables. Use that as
your initial offset to the rhumb line course direction. Once enroute
check the bearing to your destination using the weapon of your choice
- bearing compass, RDF, whatever. Your bearing should stay constant
if your offset is correct, otherwise make a correction plus or minus
and continue to recheck. There is really no excuse for being
accidently swept down current, even in Vineyard Sound.

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

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

GPS is better, way better.



They remind me of my old ham buddies clutching onto their Morse keys as if
their very lives depended on it. "You can always get through on Morse when
nothing else works.", they assure anyone listening.

That's when I bring them in to watch what happens with PSK31, a new amateur
radio text mode that uses just the sound card and an SSB receiver. It
copies THREE signals slightly off each others frequencies
SIMULTANEOUSLY....signals you can't even detect with your ears...MORSE
ears.

Don't forget to tow your horse trailer, either. You never know when your
car might conk out and strand you! Having the horses in the trailer will
allow you to fall back on older technology.

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....

Sure wish he'd get the AIS transponder, soon.....(c;

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

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....

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

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

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

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

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

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

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

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

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

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

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

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?

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

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

What is the ultimate navigation tool? Was - RDF (radio direction finding) ... do you ?
 

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?

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

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!

What is the ultimate navigation tool? Was - RDF (radio directionfinding) ... do you ?
 

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!