DR practice
 

"Flying Tadpole" wrote in message

| A gross and cruel libel on turtles.

I got permission from 'Scuttles" the turtle in my brother's Koi Pond.... I
bribed him with a lettuce leaf.

CM

DR practice
 

Interesting. So what your saying is, that airplanes are affected by
ocean currents. Just where is it you say you "fly"?

otn

JAXAshby wrote:
whatever their speed and direction relative to your speed and direction. is
that hard for you to understand, over the knee?


But to claim that there is "no qualitative difference between navigating" a
plane and boat just shows you have no practical experience doing either.


quite the contrary. it shows I have done both.

actually, in air nav you don't have to make as much allowance for winds,

for

the speed of the an airplane is many times the speed of the winds, for the
aircraft flights under discussion here.


Oh? How much allowance do you give for currents on these airplanes?

otn

DR practice
 

DR practice
 

This whole portion of this thread has come about, due to two simple post:
1. Jax took umbrage with Joe's usage of the term "DR"
2. I told jax he had one definition of the term "DR", but not the only
definition.

If you go to various source materials, you will generally find three
terms being used .... "dead reckoning", "deduced reckoning", and "ded
reckoning".
In general, you will find that all relate to a basic form of navigation
which has been in use for centuries and the differences in definition
and usage of the terms tends to vary from one source material to another
and possibly from earlier additions to newer, one group of mariners to
the next, etc.
It's not really important how *YOU* define or use these 3 terms, as they
are all closely related to the same basic navigation method. All that's
really important is that each individual in the discussion, knows how
the other is applying the 3 different/similar, terms, or if they all
mean the same.
Some people like to keep the whole process limited to
speed/direction/time, while others will introduce winds/currents and a
host of other factors, into the mix.
There is NO, one, correct definition. There are however, a number of
related and sometimes contradictory definitions and to be honest, for
me, you can use which ever one you want .... as soon as I realize yours
may be different than mine, a simple question can get me to talk about
"DR", on the same plane as you are.

EG course, trying to talk to jax on the same plane is like trying to
ride a roller coaster with no restraint mechanism.

Main message: People will use the term "DR" differently .... it's no big
deal.

otn

DR practice
 

Stick to what you know. Mathematically, incorporating additional
information (even if it has some uncertainty) can inproves the error
estimate. While aircraft may make leeway and have wind that is not
usually incorportaed in theit DR. But you knew that right?

Cheers


nav, are you saying that making more guesses *improves* the accuracy of prior
guesses?

mathematically, additional guesses degrades the accuracy of prior guesses.

what's more, aircraft also make leeway and also have current and actually have
air density differences (similar effect as the tide you mention re boats)


List Jackass and listen good. DR in flying is just compass and speed. In
marine navigation it is compass, speed, leeway, current and tide. By
allowing for these variables accuracy is much greater.


Cheers

DR practice
 

What is this extraordinary "science stuff" you know? How to ride a
bicycle perchance?

Cheers

JAXAshby wrote:

so, nav, because I know that science stuff while you don't that means "that
science stuff" does not affect where *you* are when *you* are wondering around
in a fog with only a compass and speed indicator?

how sad that you think ignorance protects you.


Yes that about sums your knowledge up.

Cheers

JAXAshby wrote:


yeah, all that physics science stuff.

DR practice
 

Not only that, tide and current are known to reasonable accuracy whereas
wind speed and direction are unknown except maybe at the airport...

Cheers


Jeff Morris wrote:

That fact the you "state it" doesn't make it so. The crosswind/crosscurrent
calculation may be the same, but there are lots of "qualitative" differences
between air navigation and nautical navigation. DR may have similar meanings
and similar problems in both, but navigation in general involves many
techniques, used in various combinations, as appropriate.

For example, how do you take soundings in a plane? Can you hear foghorns? Can
you read the windspeed from a lobster pot? DR by itself is just one technique,
and one that admittedly has certain limitations. But combined with other
techniques it can be quite useful.


"JAXAshby" wrote in message
...

jeffies, I stated from the get-go that there is no qualitative difference
between air and sea navigation.

It's a physics thing. get your wife to explain it to you.


So tell us please, jaxie, what is the difference? So far, you have only
demonstrated your ignorance in both air and nautical navigation. Why don't
you
try for space navigation?


"JAXAshby" wrote in message
...

jeffies, don't comment on how aircraft fly. you don't have a clew.

you should know **if** you did have that degree in physics you claim you

have,

but you don't.


Its very simple, jaxie: a 20 knot crosswind affects a 100 knot airplane

about

the same way that a 1 knot cross current affects a 5 knot sailboat.

There

is a
major difference, however: the wind can change dramatically with little
notice
and no way to detect it, resulting in huge potential errors for the plane,
while
the current is usually well behaved, especially if you understand the

local

conditions.

You never have done either, have you jaxie?



"JAXAshby" wrote in message
...

jeffies, pahleeeeeeeeeeeeeeeeeeeeeze ask your wife to read every last

thing

you

write **before** you hit the post key. that way we won't see the trash

you

wrote below.


PLEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEAAAAAAAAAAAAAAA AAAAAAASSSSSSSSSSSSSSSSSSSS

SSEEEEEEEEEEEEEEEEEEE. okay?


There are no aircraft flights under discussion here. However, if we're
talking
about planes where electronics might not be used, then the speed is

probably

rather low, and the wind speed could easily be 20% of the plane speed.
Worse,
you could have a significant wind shift and have no idea it happened.

In

a

boat, the currents are usually under a knot, and rarely is the

deviation

from

the prediction more than knot. You seem to be basing your entire claim

on

the
possibility of unexpected 10 knot current in totally random directions.

This

show your complete lack of experience.

Further, your completely ignoring that fact that for piloting, a major

part

of
navigation, there are many techniques that have no analogue in flying.

But

you
wouldn't know anything about this, would you?




"JAXAshby" wrote in message
...

But to claim that there is "no qualitative difference between

navigating"

a

plane and boat just shows you have no practical experience doing

either.

quite the contrary. it shows I have done both.

actually, in air nav you don't have to make as much allowance for

winds,

for

the speed of the an airplane is many times the speed of the winds,

for

the

aircraft flights under discussion here.

DR practice
 

JAXAshby wrote:
nav, are you saying that making more guesses *improves* the accuracy
of prior guesses?

mathematically, additional guesses degrades the accuracy of prior
guesses.

It's a refinement of the same guess. If you know you're in a 1kt current, a
guess based purely on your steered course and speed would be less accurate
than if you refined the guess by accounting for the current.


--
Wally
www.artbywally.com
www.wally.myby.co.uk

DR practice
 

Subject: DR practice
From: (JAXAshby)
Date: 07/18/2004 17:31 Pacific Standard Time
Message-id:

One
reason straight DR in zero visibility may be frowned on with planes.

no, the reason it is illegal is that you can not know where you are. period,
as in can not.

DR in a boat is okay when you are hundreds of miles from any rocks. It is
not
okay when there is anything around to hit.

In all the years you've harped on this subject, it's become painfully clear you
have not and can not grasp the basic practices of "DR".
You've read somplace that the term should only be ded reckoning and that it
only involves speed,time, and heading, and will go to your death bed "knowing"
that anything else is sacrilege.
Problem is, most who spend any time on the water have learned to use other
things to help improve their "DR" plots so that they can safely navigate where
you would never tread.
Problem is, these things don't fit in your narrow view of DR, so you can't
accept them as being DR or being useful and trying to explain these things to
you is a waste of time as you can't seem to comprehend them or make use of
them.
In reality, you need to do or watch someone do these things, so you can learn
how to do them but odds of you ever doing that are slim to none.

Don't waste your time responding, as I know you will not have understood the
point being made.

Shen

PS recreational boats regularly hit rocks even with gps

DR practice
 

Jaxie's simplistic mind can't cope with mixing two concepts. He confuses "using
DR" with "relying 100% on DR." He never figured out that combining DR with
other info, such as observing lobster pots, depth soundings, and fog signals is
generally adequate.

He seems terrified of coastal cruising, but at the same time claims that
learning both DR and piloting techniques is worthless. My favorite "jaxisms"
involve his misunderstanding of piloting and his belief that compasses are
worthless.

-------------------

On Navigation (or is he talking about snakes?):
This one kept us going for a month or so - Jax insists that piloting skills are
not needed in sight of land.

"scootss, you need *piloting* to "get around" in the Cheasepeake? All that
water and land and islands and markers and lights and boas confuse you?"

-------------------

Just to make sure he meant that:

you claimed that
piloting skills are not needed for sailing waters like LIS.

"They are not. You can see everything easily. Getting lost on western LIS is
impossible (unless you're dumb enough to go out in one of the rare fogs.)"

-----------
... Somewhere in there you implied
that taking a course on navigation was a total waste of time and money.

"You need a nav course to see a daymarker a half mile away? (besides, one of the
**serious** problems of a nav course -- as taught by the USPS -- is that a
compass and knot log is all you need to avoid hitting the rocks in a fog.)"

------------------------
on compasses and navigation:
Jax has a pathological fear of using a compass. Since he never learned any
piloting skills, he believes the compass is useless:

"a compass never has told you anything other than which way is North and so
never was worth much as a "navigation" tool."
---------
"no, jeffie, this the point that JAX with the experience tells you without that
you can't navigate with a compass."

--------------------------------
On variation & compasses:
Since he never uses a compass, he doesn't understand variation:

I think it's about 14 degree east here in nyc.

That's strange, my chart of New York City says
"Var 13 degrees 15 minutes WEST"

jeff, if you say it's west instead of east, I say okay. I use charts of nyc
area to know where the rocks are. Compass isn't much use there, is it?

--------------------------
On compass dip and variation, he thinks dip is built into the compass:

"markie, dip is a function of the compass construction. Variation is a function
of the Earth. Anyone who claims to be "The Navigator" should know this, don't
you think?"