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

Wayne.B wrote:
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.


In other words, if you don't do this, you'll spiral in, just like I
said. Even with a GPS, you'll have to understand setting waypoints,
x-track, etc.

If you take the position that humans are completely competent and
never make mistakes, and that equipment never fails, then your
conclusion follows quite naturally.

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

Larry wrote:
....
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;


Sounds to me like you have a boatload of people who have forgotten how
to use a compass, if they ever knew.

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

Jeff wrote:
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.




No, 'I'... said inexpensive.

I was hoping you, or some other reader, might have a good suggestion for
obtaining a suitable windup.

Cordially,
Courtney

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

"Bob" wrote in news:1142065241.058975.105470
@i40g2000cwc.googlegroups.com:

where would you find the tubes?


http://www.tubesandmore.com/

Stay away from Ruby tubes from China....They suck. Russian tubes are the
best!

Russia still builds tubes because tubes survive the EMP of an atomic blast.
The scary part is there are people in all government bureaucracies,
including mine, that worry about electronics surviving.

I sold 4 tubes just this week! Old Hammond organs are all tubes...(c;

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

Jeff wrote in :

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



Unfortunately, there's not "stupidity charge" for going to sea without the
latest and best equipment. One guy docked at J-dock in an empty slip
rented by a friend. He didn't stay long, just long enough to go up to the
marina office and rent a slip for the night. He couldn't call them because
HE DIDN'T HAVE A VHF RADIO OR CELLPHONE! The gas dock was full.

It's amazing how many boats are equipped like this.....

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

Jeff wrote in :

Sounds to me like you have a boatload of people who have forgotten how
to use a compass, if they ever knew.



You mean that big round thingy we moved out of the way to install the radar
display that bobs around and spins crazy when the waves slap the hull?
What kind of reading can you get from something swinging 30 degrees off
course?

Just kidding. It's there and we use it, sort of. Over time, we made up a
compass correction chart for it using the chartplotter headings and compass
readings. The chart looks like a big sinewave. The compass reads
correctly at 2 points where the chart crosses zero. Otherwise, it's off by
as much as 13 degrees at two other points at the peaks. Totally disabling
DC currents has no effect. I have all the wiring as far from it as
practical. There's no close magnetic objects, either. All the electronics
is plastic with copper circuit boards. We tried to compensate it out with
the compensating adjustments and this chart is the result of the "best
setting" of those magnets.

Try that with your compass. Chart its error against the GPS headings over
time as you sail and plot it on a line chart. I was amazed how far off it
is. Sure glad we don't use it for NAVIGATION!....(C;

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

Larry wrote:
Jeff wrote in :


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




Unfortunately, there's not "stupidity charge" for going to sea without the
latest and best equipment. One guy docked at J-dock in an empty slip
rented by a friend. He didn't stay long, just long enough to go up to the
marina office and rent a slip for the night. He couldn't call them because
HE DIDN'T HAVE A VHF RADIO OR CELLPHONE! The gas dock was full.

It's amazing how many boats are equipped like this.....

Unfortunately, not everyone get to crew on a rich person's boat with
all the latest gear, updated every year. Most of us make do with the
best we can. All the gear in the world doesn't compensate for lack of
knowledge and experience. I remember watching a 50 foot trawler run
aground on what looked like obvious shoaling to me. When I asked if
they need help he just mumbled "I don't understand ... we were going
right down the magenta line ..." This was on the ICW in GA.

30 years no one I knew had VHF, LORAN, or RADAR. Some of us had depth
sounders and RDF. But we all knew how to take a running fix, we all
knew how to read the water.

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

Jeff wrote in
:

Larry wrote:
Jeff wrote in
:


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




Unfortunately, there's not "stupidity charge" for going to sea
without the latest and best equipment. One guy docked at J-dock in
an empty slip rented by a friend. He didn't stay long, just long
enough to go up to the marina office and rent a slip for the night.
He couldn't call them because HE DIDN'T HAVE A VHF RADIO OR
CELLPHONE! The gas dock was full.

It's amazing how many boats are equipped like this.....

Unfortunately, not everyone get to crew on a rich person's boat with
all the latest gear, updated every year. Most of us make do with the
best we can. All the gear in the world doesn't compensate for lack of
knowledge and experience. I remember watching a 50 foot trawler run
aground on what looked like obvious shoaling to me. When I asked if
they need help he just mumbled "I don't understand ... we were going
right down the magenta line ..." This was on the ICW in GA.

30 years no one I knew had VHF, LORAN, or RADAR. Some of us had depth
sounders and RDF. But we all knew how to take a running fix, we all
knew how to read the water.


LOL Can remember so many who swore they were in the middle of the
channel going down the ICW yet were hard aground.
How often such a simple act of watching their own wake and knowing what
it meant when it started overtaking them on one side or both sides would
have saved them a lot of embarassment and/or damage while following the
"magenta line".

otn

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

On 3 Mar 2006 14:57:52 -0800, "purple_stars"
wrote:

i know everyone uses gps. enough said.

but i also know that a lot of cruisers (most ? all ? all of the smart
ones ?!) use alternate methods of finding their position and navigating
to both keep their skills current in case of emergency, to double check
the gps equipment, etc, etc. some use celestial navigation, everyone
uses piloting skills, and on and on.

but do you still use RDF ?

if so, could you talk a little about what equipment you keep on board
for it ?

most of the RDF equipment i've seen looks really old!


As your question didn't pull any responses, I'll chew the rag, for
what it's worth.
There are at least four DF systems in use.
1) VHFDF
2) UHFDF
3) Switched antenna radio
4) movable directional antenna radio.

1) & 2) have only seen much use around planes. They are line of sight
aids. In the air, that's ok, hunkered down on the briney, not so
helpful.

3) Hams have built and used circular antenna arrays to provide a
rotating directional sweep.

4) Commercial radios with a top rotating ferrite antenna and a compass
rose. Panasonic made a portable 6 band of this kind - I have one in
the bathroom.

Not sure if radios in cat 4) are still available, but they would be a
natural low cost choice.

Brian Whatcott Altus OK
p.s. GPS made a lot of aids obsolete, right there.

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

In article ,
Larry wrote:

Jeff wrote in :

Sounds to me like you have a boatload of people who have forgotten how
to use a compass, if they ever knew.



You mean that big round thingy we moved out of the way to install the radar
display that bobs around and spins crazy when the waves slap the hull?
What kind of reading can you get from something swinging 30 degrees off
course?

Just kidding. It's there and we use it, sort of. Over time, we made up a
compass correction chart for it using the chartplotter headings and compass
readings. The chart looks like a big sinewave. The compass reads
correctly at 2 points where the chart crosses zero. Otherwise, it's off by
as much as 13 degrees at two other points at the peaks. Totally disabling
DC currents has no effect. I have all the wiring as far from it as
practical. There's no close magnetic objects, either. All the electronics
is plastic with copper circuit boards. We tried to compensate it out with
the compensating adjustments and this chart is the result of the "best
setting" of those magnets.

Try that with your compass. Chart its error against the GPS headings over
time as you sail and plot it on a line chart. I was amazed how far off it
is. Sure glad we don't use it for NAVIGATION!....(C;


sounds like someone needs or hire a GOOD Compass Adjuster to come
out and "Swing" that compass........

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

Larry wrote:
Jeff wrote in :


Sounds to me like you have a boatload of people who have forgotten how
to use a compass, if they ever knew.




You mean that big round thingy we moved out of the way to install the radar
display that bobs around and spins crazy when the waves slap the hull?
What kind of reading can you get from something swinging 30 degrees off
course?

Just kidding. It's there and we use it, sort of. Over time, we made up a
compass correction chart for it using the chartplotter headings and compass
readings. The chart looks like a big sinewave. The compass reads
correctly at 2 points where the chart crosses zero. Otherwise, it's off by
as much as 13 degrees at two other points at the peaks. Totally disabling
DC currents has no effect. I have all the wiring as far from it as
practical. There's no close magnetic objects, either. All the electronics
is plastic with copper circuit boards. We tried to compensate it out with
the compensating adjustments and this chart is the result of the "best
setting" of those magnets.

Try that with your compass. Chart its error against the GPS headings over
time as you sail and plot it on a line chart. I was amazed how far off it
is. Sure glad we don't use it for NAVIGATION!....(C;

The problem here is the compass heading is the direction the boat is
pointing, the GPS heading is the direction the boat is moving. The two
are always different, always! You can't swing a compass with a typical
GPS. The GPS that give proper heading have two recievers (one at each
end of the boat) and calculate the ships heading based on the different
positions each one gives. There is stille error.

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

Gary wrote:
Larry wrote:
....

Try that with your compass. Chart its error against the GPS headings
over time as you sail and plot it on a line chart. I was amazed how
far off it is. Sure glad we don't use it for NAVIGATION!....(C;

The problem here is the compass heading is the direction the boat is
pointing, the GPS heading is the direction the boat is moving. The two
are always different, always! You can't swing a compass with a typical
GPS. The GPS that give proper heading have two recievers (one at each
end of the boat) and calculate the ships heading based on the different
positions each one gives. There is stille error.

At my helm I have a normal compass (deviation less than 2 degrees, as
near as I can tell), the GPS COG, the autopilot setting, and the
autopilot fluxgate compass. It is rare that even two of these will
agree, and often there are significant differences. I sort of enjoy
this seeming vagueness, but it drives my wife crazy, because she wants
to believe that one is "real" and therefore the others are "wrong"!

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

"Gary" wrote

are always different, always! You can't swing a compass with a
typical GPS.

Why not? Pick a slack current time and set up a waypoint to distant
landmark. Stop the boat and check the compass. You need to do it on
multiple headings or else have landmark waypoints about every 30
degrees around the horizon. If you're in a good coverage period and
the landmarks are several miles away, it's going to be very accurate.

--

Roger Long

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

On Tue, 14 Mar 2006 16:20:36 GMT, "Roger Long"
wrote:

Pick a slack current time and set up a waypoint to distant
landmark.

Little or no wind is also very desirable, especially for a high
profile boat. Trying to determine if the current is really slack on a
windy day is next to impossible.

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

Up here in Maine, at least, we are blessed with all these fixed
reference points and current direction and rough velocity indicators,
known by the quaint local term as "Lobster Pots".

--

Roger Long



"Dave" wrote in message
...
On Tue, 14 Mar 2006 13:44:26 -0500, Wayne.B
said:


Pick a slack current time and set up a waypoint to distant
landmark.

Little or no wind is also very desirable, especially for a high
profile boat. Trying to determine if the current is really slack on
a
windy day is next to impossible.

What am I missing here? You need to be able to see your compass
heading when
pointed directly at the waypoint, and the GPS reading at the same
time.
Seems to me it would take an awful lot of wind or current to prevent
you
from doing that.

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

Roger Long wrote:
"Gary" wrote


are always different, always! You can't swing a compass with a
typical GPS.


Why not? Pick a slack current time and set up a waypoint to distant
landmark. Stop the boat and check the compass. You need to do it on
multiple headings or else have landmark waypoints about every 30
degrees around the horizon. If you're in a good coverage period and
the landmarks are several miles away, it's going to be very accurate.

I didn't think about using the course to steer to a waypoint function.
That would certainly be much better than using the COG function. I am
no sure what the original poster used but your idea seems sound.

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

"Roger Long" wrote in news:o3CRf.9136$Da7.2891
@twister.nyroc.rr.com:

Why not? Pick a slack current time and set up a waypoint to distant
landmark. Stop the boat and check the compass. You need to do it on
multiple headings or else have landmark waypoints about every 30
degrees around the horizon. If you're in a good coverage period and
the landmarks are several miles away, it's going to be very accurate.



Shhh...Don't confuse them when they're on a roll....(c;

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

"Roger Long" wrote in news:pKERf.17997$jf2.16363
@twister.nyroc.rr.com:

known by the quaint local term as "Lobster Pots".


In Charleston, they're referred to as "crab traps".....or more correctly,
"goddamned crab traps"....(c;

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

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.

Bingo!

I've been lurking on this thread waiting for someone to bring up the
key problem with GPS: sure it's mighty-fine accurate, but it's just a
lat-lon, *useless* until related to navigational features of interest
somehow, usually by consulting a chart, electronic or paper. If the
chart is not on the same datum and is also mighty-fine accurate, then
the *chart* is the weak link in the GPS/chart system of navigation.

And charts are accurate at best to a pencil width or two at the
original scale of the chart. Blowing the chart up by a factor of a
thousand on yer super-fancy GPS chartplotter so you can see your slip
makes that pencil width turn into maybe 200 feet, even on a detailed
harbor chart. A pencil width or two on an approach or regional chart
can turn into a half mile or more. So that's the level of accuracy in
a best case scenario for the GPS/Chart system.

Problem is charts are just a faint shadow of the real world:
Cartographers miss things, misplot things and mislabel things. Some
things can't be accurately plotted, some deep-set buoys can swing on
their moorings by a half mile, for example. Charts are not real-time,
as they age, changes occur in the real world which don't magically
appear on the chart. Charts are on many different datums, for example,
if you don't have the brains to switch your GPS receiver datum from
WGS84 to NAD27 when you switch to a NAD27 chart, up to 500 feet or so
of error auto-magically appears in all your plotting. Charts are
necessarily incomplete; other ships, massive breaking waves, flotsam,
commercial fishing gear, etc., don't appear on them. And, if you're
sailing in out of the way places on the planet, the chart, although
pretty, could be a P.O.S., positions off by miles, inconsistently; and
show things which didn't exist a the time of survey and omit things
which did.

The result of thinking your GPS is accurate to a few feet when you're
actually using GPS/chart system? Disaster! On a cruise in the Sea of
Cortez last month we anchored a half mile inland in a few spots,
transited breaking shoals, saw islands to port pass to starboard; all
according to our color big screen GPS chartplotter with a fresh chip.
Every year here in Southern California several powerboats run up on
Huntington Beach at cruising speed, because they zoomed in to San
Diego Buoy #1 on their whiz-bang GPS/chartplotter, set a waypoint,
panned to Angel's Gate in Los Angeles, set a waypoint, created a route,
locked in the autopilot, then went below and hit the sauce. Problem
is that route grazes land halfway through the passage! I'm sure you
can come up with your own stories; and I've got a few of my own where
I've been surprised by taking the GPS picture as gospel.

What GPS has done is allow nitwits to navigate right on the money, most
of the time, and not develop other navigation skills. Used to be
natural selection took care of them sooner or later. Cruising's going
to hell, a high-tech solution to every problem: sail handling? -
roller furling!, water? - watermaker!, batteries? - battery monitor!,
navigation? - GPS! All very alluring, but harsh mistresses when they
go south.

Now, radar, depthsounder, RDF and the Mark I eyeball and earball are
not derivative navigational tools; there is no lat-lon fixed scale
chart accuracy correct datum ju-ju going on. They have their problems,
but on a good day you are directly relating the real world to your
position, no third parties - satellites, master control stations and
cartographers involved. And, as you "zoom in", i.e., get closer to the
thing in question, accuracy gets better linearly, unlike zooming in on
a chartplotter. It's much better to know that navaid in the fog is
actually-right-now 200 yards off your starboard bow than to think the
sexy picture on your chartplotter is reality (which has it off your
stern).

That being said, I'm a multi-unit GPS owner too, mighty useful, but
it's more of a glance now and then and autopilot brain for me. Good
for detecting current and leeway effects, where the GPS is essentially
calculating a vector between where you are now and where you were a
short while ago, no chart referencing there. Good for calling BS on
your chart, if the Mark I's are telling you a different story. Really
good for returning to the *exact* same spot where you've taken a GPS
waypoint previously, or relating your position to another vessel's
reported GPS position (if they're dialed into the same datum). Super
accurate clock, too.

But it's no magic bullet, because of the chart problem.

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

Mark wrote:
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.

Bingo!

-snip-

And charts are accurate at best to a pencil width or two at the
original scale of the chart. Blowing the chart up by a factor of a
thousand on yer super-fancy GPS chartplotter so you can see your slip
makes that pencil width turn into maybe 200 feet, even on a detailed
harbor chart. A pencil width or two on an approach or regional chart
can turn into a half mile or more. So that's the level of accuracy in
a best case scenario for the GPS/Chart system.

Problem is charts are just a faint shadow of the real world:
Cartographers miss things, misplot things and mislabel things. Some
things can't be accurately plotted, some deep-set buoys can swing on
their moorings by a half mile, for example. Charts are not real-time,
as they age, changes occur in the real world which don't magically
appear on the chart. Charts are on many different datums, for example,
if you don't have the brains to switch your GPS receiver datum from
WGS84 to NAD27 when you switch to a NAD27 chart, up to 500 feet or so
of error auto-magically appears in all your plotting. Charts are
necessarily incomplete; other ships, massive breaking waves, flotsam,
commercial fishing gear, etc., don't appear on them. And, if you're
sailing in out of the way places on the planet, the chart, although
pretty, could be a P.O.S., positions off by miles, inconsistently; and
show things which didn't exist a the time of survey and omit things
which did.

-snip-

What GPS has done is allow nitwits to navigate right on the money, most
of the time, and not develop other navigation skills. Used to be
natural selection took care of them sooner or later. Cruising's going
to hell, a high-tech solution to every problem: sail handling? -
roller furling!, water? - watermaker!, batteries? - battery monitor!,
navigation? - GPS! All very alluring, but harsh mistresses when they
go south.

Now, radar, depthsounder, RDF and the Mark I eyeball and earball are
not derivative navigational tools; there is no lat-lon fixed scale
chart accuracy correct datum ju-ju going on. They have their problems,
but on a good day you are directly relating the real world to your
position, no third parties - satellites, master control stations and
cartographers involved. And, as you "zoom in", i.e., get closer to the
thing in question, accuracy gets better linearly, unlike zooming in on
a chartplotter. It's much better to know that navaid in the fog is
actually-right-now 200 yards off your starboard bow than to think the
sexy picture on your chartplotter is reality (which has it off your
stern).

-snip-

But it's no magic bullet, because of the chart problem.

I enjoyed reading your dissertation. You are right about the GPS being
an enabler for folks with lesser skills. You are right about chart
inaccuracies. There is a bit of a leap when though if you don't point
out that all those same inaccuracies also apply to the traditionl forms
of navigation. The depth sounder has error and so does the charted
soundings. The RDF has bearing error (cone of position) and so does the
plotting of the transmitter on the chart. Radar has many errors; a
radar mile is 6000 feet. Depending on the range and height of tide, the
land you are looking at on radar can be completely different from what
is charted, and of course it is a skill to plot a radar fix so it is
even close to where you are. At the very best, getting a fix on the
chart tells you where you were some minutes ago. Visual fixes are the
meat and potatoes of pilotage and coastal nav but require a great degree
of skill to quickly shoot, plot and put a DR on so that you can see
where you are, not where you were. It is still an educated guess given
that tide and wind can make your position differ from the DR. Even if
the wind and tide are applied to the fix giving you an EP (estimated
position), error creeps in.

Good navigation is an art. GPS has made it much more scientific but the
interpetation of the information and the combining of that info with
other info is still an art. Practice is the key.

Gary

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

On Sun, 12 Mar 2006 14:40:36 GMT, Brian Whatcott
wrote:

On 3 Mar 2006 14:57:52 -0800, "purple_stars"
wrote:

//
but do you still use RDF ?

[brian]
As your question didn't pull any responses, I'll chew the rag, for
what it's worth.
There are at least four DF systems in use.
///
Brian Whatcott Altus OK
p.s. GPS made a lot of aids obsolete, right there.

Holy smoke!

Next time I looked there were dozens of responses, all BEFORE my note.

Ah well....


Brian Whatcott Altus OK

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

There is a bit of a leap when though if you don't point
out that all those same inaccuracies also apply to the traditionl forms

of navigation.

Indeed they have their problems; what I was trying to point out is they
are direct observations emitted from your boat, not dependent on a
chart (excluding RDF g). Much more like the Mark I eyeball and
earball than GPS is.

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

There is a bit of a leap when though if you don't point out that all those
same inaccuracies also apply to the traditionl forms of navigation.


Indeed they have their problems; what I was trying to point out is they
are direct observations emitted from your boat (well, not RDF g).
They still provide useful information even if you have no chart. Much
more like the Mark I eyeball and earball than GPS is.

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

The technique is still valuable. I.E. If you frequent an area plagued
by occasional fog, RDF observations recorded during periods of good
visibility would be useable when conditions were bad, even if GPS and
actual charts disagree. This presupposes that you can survive the trip
on a good day using traditional methods.

Preserving options is a viable method. Relying on a single method that
can not be absolutely guaranteed in a case of dead batteries or gps
instrument is an invitation the fates will not ignore indefinitely.

Terry K

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

The technique is still valuable. I.E. If you frequent an area plagued
by occasional fog, RDF observations recorded during periods of good
visibility would be useable when conditions were bad, even if GPS and
actual charts disagree.

Right on. RDF is most useful if the beacon is an actual marine navaid
on structures of interest, like an entrance jetty, which you can "home
in" on. Then, when fogbound and "close-in" , i.e., a few hundred
yards, it can tell you which side of the item you're passing on,
without benefit of a chart. It's less reliable when you're far
offshore or the signal emitter is not near shore (like a commercial
radio station antenna inland), because of the bending of the apparent
direction of the antenna by topography, etc.

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

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.

Bingo!

I've been lurking on this thread waiting for someone to bring up the
key problem with GPS: sure it's mighty-fine accurate, but it's just a
lat-lon, *useless* until related to navigational features of interest
somehow, usually by consulting a chart, electronic or paper.

All navigational systems need maps. All maps need frequent updating. GPS is
not an exception to that rule.


Some
things can't be accurately plotted, some deep-set buoys can swing on
their moorings by a half mile, for example.

If you have GPS why in the world are you navigating to buoys? GPS replaces
the need for a buoy.



What GPS has done is allow nitwits to navigate right on the money, most
of the time, and not develop other navigation skills.

Its appropriate that you understand the word "nitwit" after you tried to use
GPS to navigate to a buoy above.

Used to be natural selection took care of them sooner or later.
Cruising's going
to hell...

I was wondering why you were trying to make technical arguments when you
clearly have no technical understanding. Then this last sentence explained
it all. You just want to complain that the world is going to hell. Your
post is nothing more than an emotional outburst from an old washed up guy
who is growing angry. Everything else in your post should be ignored as
nonsensical.