Gary wrote in
news:Z26Pf.112412$H%4.97127@pd7tw2no:

otnmbrd wrote:
Gary wrote in


How does putting a GPS fix on the chart help you forget your boat's
reaction to weather, currents (it tells you them), DRing etc? If
anything it proves your estimated position.


Sure it tells you what, but it doesn't tell you why. Hey, good short
term plan, the GPS says steer 270..... course, this could mean you'll
fight the currents/winds , rather than use them: drive over that
rock.....

The GPS doesn't say steer anything. It just tells you where you are,
exactly, most of the time.

Generally the units I use tell you the course to steer to the next
waypoint.

GPS is a tool and all too many consider it the ultimate tool. It's
not and all too many get into the habit of forgetting to question the
"why" of what it says.
It is currently the ultimate tool but not the only tool and not
infallible. But it is the best.....generally, most of the time,
right?

For offshore navigation, I'd say yes. For inshore, I'd say no, but it
ranks close.


What, in your opinion is the ultimate navigation tool?

Me


BTW, the GPS doesn't tell you your boat's reaction to weather,
currents. It's telling you your reaction to the cumulative conditions
you are in. YOU have to figure out your boats reactions to weather,
currents.


otn

It is the total cumulative reaction that counts. It's the same
information you get off two fixes whether taken by stars, radar,
visually, or GPS. The information is total cumulation of wind and
current affecting the ship. That is what you want. The GPS just does
it quicker and more accurately and more often.

No, it only tells you the cumulative. Once again, YOU need to figure out
the "why" to know how the "cumulative" came about.
For instance, you are on a displacement type boat with 20k of wind on
the port beam. Your GPS tells you, you are making your course good (no
set or drift). What does that tell you?


otn

otnmbrd wrote:
[snip]
No, it only tells you the cumulative. Once again, YOU need to figure out
the "why" to know how the "cumulative" came about.
For instance, you are on a displacement type boat with 20k of wind on
the port beam. Your GPS tells you, you are making your course good (no
set or drift). What does that tell you?

hi otn,

what you are saying is the same as what the fat navigation book i've
been studying is saying, that the navigator navigates and the GPS just
gives a fix, which is one of the many interesting things a navigator
needs to know to do his/her job. it's brilliant at giving fixes,
fortunately. like you are saying, navigation is more than getting from
A to B, which is what GPS is great at ... but about getting from A to B
safely, in good time, with good weather, with a smooth ride, following
advantageous winds and currents, arriving at tricky harbor entrances in
daylight, etc, etc, things that GPS doesn't know anything about. even
the navigator doesn't know them all, s/he can only use his/her best
judgement and experience when combining the information gained by the
navigational aids at hand such as GPS fixes, wind direction
measurements, wind speed, calculations of currents, route books showing
statistical "best times" for advantageous conditions, and on and on.
it's all important in creating "situational awareness", and the more
accurate information upon which to make a judgement, the better.

which is the most important navigational tool in the middle of the
ocean ? like otn said, himself (i'm assuming you are male otn,
apologies if i'm wrong!). and other really important tools are .. if
using paper charts (doesn't everyone do their real work on paper charts
?) ... good updated charts, pencils and scrap paper, a straight edge,
GPS receivers, wind vane, a calculator, good reference information,
depth finder, radios, etc, etc .. and the most important information
are GPS fixes, current heading, heading made true, magnetic direction
(which is only on occasion coincidentally the same as your GPS
direction), weather reports, etc, etc. but in the end, it is the
totality of all of this information combined in the navigator's own
squishy brain that is the most important thing, and the experience and
knowledge of the navigator to make good judgements that keeps a boat
off of a reef.

in that context, i still think RDF would be interesting to use. if
you're just sitting there in the ocean moving along at a nice pace
without a speck of land in sight, i, personally, would gain an added
measure of comfort in my own decisions by knowing that WABC's
transmitter at location lat/long is located 10 degrees off of
starboard. yes, i want a GPS fix too (goes without saying), and i want
to know a lot more than that, but i'd like to know that RDF information
too if i had the choice between having it and not having it. and as
far as that goes, i'd be happy with celestial fixes along the way too,
even relatively inaccurate ones that put me in the same neighborhood.
and i'd be happy seeing stationary clouds on the horizon forming over
and island, sea birds, knowing what location nearby vessels think they
are at, etc, too, i want as much information as i can get. all of
these perceptions form a picture in the navigator's mind that you hope
is the same as what reality is.

and i'm not saying that anyone here doesn't think the same kind of
thing, i would assume that everyone posting on this thread has some
similar kind of idea in mind even if there is debate over whether RDF
or celestial sights are worth including for the amount of trouble
and/or equipment weight, etc, that's involved. but i personally don't
see RDF, celestial sights, or sea birds as "un-necessary" or "something
to do when bored", i see them as interesting information that i would
rather have than not. i don't see how excluding any of that
information is smart as a goal unto itself .. and for those involved in
a ****ing contest in this thread, i'm not trying to infer that you
think it's a bright idea either. so don't **** on me! lol.

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

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.

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.

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!

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.

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!

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

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