Affordable Charts? Finally?
 

On Oct 23, 5:18*pm, Wayne.B wrote:
On 23 Oct 2006 15:57:50 -0700, "Chuck Gould"

wrote:
Can it be? The entire inventory of NOAA charts now available for about
what we used to pay for one or two paper charts? *If so, that would be
great.Why would you pay $30 or $40 when you can download the exact same
charts for free?

*That* (free) is about as affordable as you can get. * :-)

http://nauticalcharts.noaa.gov/mcd/Raster/download.htm


I think the value is in the indexing and organizing, along with the
sampling of various electro-nav programs contained on the disc. I don't
know about you, but I'm not inclined to spend too many hours at a task
in order to save 30 bucks.

Affordable Charts? Finally?
 

Gene Kearns wrote in message
...
On Tue, 24 Oct 2006 12:19:51 -0400, "Eisboch" wrote:


"Calif Bill" wrote in message
thlink.net...



Burned CD's can change. The reason being the construction. The
critical
part of a CD is not the clear side but the shiny side. A pressed CD has
the dimples pressed in and then the coating is applied, and the distance
from the surface to the reflective coating does not change. A burned
CD,
diffuses an internal material. If heat and chemistry happen, that
diffusion can grow or change. The reason a CD works is the light source
is reflected from the shiny coating or the diffused internal area. The
diffused or dimple is 1/2 wave length in depth, so you get a
cancellation
of light. A dark spot. If there is damage to the reflective surface,
then bad data.



I read at some point in time:

A burned CD has an approximate storage life of only 3 years before it can
start having data errors simply due to aging. They are not recommended
for
long term storage of important documents or files.

Interestingly, magnetic media (tapes) have an estimated data storage life
of
approximately 100 years.

Eisboch


http://www.scienceagogo.com/news/200...runc_sys.shtml


I think they are talking about commercial originals. The ones you create on
your CD or DVD burner on your computer (CD-R, DVD-RW) are the ones that have
a much shorter data storage life, according to what I read. I have some
homemade CDs that are a few years old though .... and they still work. I
think ..... (haven't used them in a while)

Eisboch

Affordable Charts? Finally?
 

Eisboch wrote:
Gene Kearns wrote in message
...
On Tue, 24 Oct 2006 12:19:51 -0400, "Eisboch" wrote:


"Calif Bill" wrote in message
thlink.net...



Burned CD's can change. The reason being the construction. The
critical
part of a CD is not the clear side but the shiny side. A pressed CD has
the dimples pressed in and then the coating is applied, and the distance
from the surface to the reflective coating does not change. A burned
CD,
diffuses an internal material. If heat and chemistry happen, that
diffusion can grow or change. The reason a CD works is the light source
is reflected from the shiny coating or the diffused internal area. The
diffused or dimple is 1/2 wave length in depth, so you get a
cancellation
of light. A dark spot. If there is damage to the reflective surface,
then bad data.



I read at some point in time:

A burned CD has an approximate storage life of only 3 years before it can
start having data errors simply due to aging. They are not recommended
for
long term storage of important documents or files.

Interestingly, magnetic media (tapes) have an estimated data storage life
of
approximately 100 years.

Eisboch


http://www.scienceagogo.com/news/200...runc_sys.shtml


I think they are talking about commercial originals. The ones you create on
your CD or DVD burner on your computer (CD-R, DVD-RW) are the ones that have
a much shorter data storage life, according to what I read. I have some
homemade CDs that are a few years old though .... and they still work. I
think ..... (haven't used them in a while)

Eisboch


Same here. I have never had a CD that I burnt fail yet, although I do
have to clean them once in a while after being handled a lot.

What theoretically is supposed to happen to the data burnt onto CD's
over time?

Affordable Charts? Finally?
 

"JimH" wrote in message
oups.com...



Same here. I have never had a CD that I burnt fail yet, although I do
have to clean them once in a while after being handled a lot.

What theoretically is supposed to happen to the data burnt onto CD's
over time?


I don't know. The original music CD was simply a polycarbonate disk coated
with aluminum (done in a vacuum process called "sputtering" and then
protected with an overcoat of lacquer done in a spin process.

A CD-R differs in the respect that there is an additional layer of some type
of organic dye that reacts to the laser when writing data. I suspect that
it is the stability of the dye that has been exposed to the beam that
determines storage life.

I looked around the 'net and there are all kinds of opinions on storage life
ranging from a few years to over 100 years. Heat and humidity appears to be
the determining factors, other than physical abuse or damage.

Eisboch

Affordable Charts? Finally?
 

"Eisboch" wrote in message
...

"JimH" wrote in message
oups.com...



Same here. I have never had a CD that I burnt fail yet, although I do
have to clean them once in a while after being handled a lot.

What theoretically is supposed to happen to the data burnt onto CD's
over time?


I don't know. The original music CD was simply a polycarbonate disk
coated with aluminum (done in a vacuum process called "sputtering" and
then protected with an overcoat of lacquer done in a spin process.

A CD-R differs in the respect that there is an additional layer of some
type of organic dye that reacts to the laser when writing data. I suspect
that it is the stability of the dye that has been exposed to the beam that
determines storage life.

I looked around the 'net and there are all kinds of opinions on storage
life ranging from a few years to over 100 years. Heat and humidity
appears to be the determining factors, other than physical abuse or
damage.

Eisboch


I don't know how old this article is, but it does list results from quality
testing of CD-R's from various manufacturers:

http://www.cdmediaworld.com/hardware..._quality.shtml

Affordable Charts? Finally?
 

Eisboch wrote:
"JimH" wrote in message
oups.com...



Same here. I have never had a CD that I burnt fail yet, although I do
have to clean them once in a while after being handled a lot.

What theoretically is supposed to happen to the data burnt onto CD's
over time?



I don't know. The original music CD was simply a polycarbonate disk coated
with aluminum (done in a vacuum process called "sputtering" and then
protected with an overcoat of lacquer done in a spin process.

A CD-R differs in the respect that there is an additional layer of some type
of organic dye that reacts to the laser when writing data. I suspect that
it is the stability of the dye that has been exposed to the beam that
determines storage life.

I looked around the 'net and there are all kinds of opinions on storage life
ranging from a few years to over 100 years. Heat and humidity appears to be
the determining factors, other than physical abuse or damage.

Eisboch




I've had a number of them deteriorate in 5-7 years, many of them were
really cheap blanks I used to backup my audio CD's and left in my car,
so in addition to being cheap they endured temperature extremes. They
weren't visually damaged but skipped more and more until they wouldn't
play. I've had other CD-Rs more than 10 years old still fine.

Affordable Charts? Finally?
 

Why are burned DVD's notoriously unreliable? I know there are problems
with DVD+ and DVD- and people trying to "burn" protected DVD's, but if
it is in the correct format and the orginal is not protected, why are
they having problems? I really have not had any problems with viewing
burned DVD's, is it just because I am lucky?

Burned DVD video seems far more tolerant of errors. I've had HORRENDOUSLY
bad reliability problems with burned DVD media. This being from several
different brand discs, different burners, software, PCs and even locations.
Seems a good many discs just don't want to let you record multi-gig files
onto them. Well, they'll let you RECORD but you're screwed if you want to
read them back whole. And I'm talking about storage intervals of sometimes
less than ONE MONTH! This in a controlled temp/humidity environment. It's
bad enough that I've gone back to TAPE.

Note, I'm talking about DVDs here, not CDs. I've had better luck with CD-R
media, but they're not large enough to hold the files involved (large
..tar.bz archives of XML data)

-Bill Kearney

Affordable Charts? Finally?
 

"Bill Kearney" wrote in message
...
Why are burned DVD's notoriously unreliable? I know there are problems
with DVD+ and DVD- and people trying to "burn" protected DVD's, but if
it is in the correct format and the orginal is not protected, why are
they having problems? I really have not had any problems with viewing
burned DVD's, is it just because I am lucky?

Burned DVD video seems far more tolerant of errors. I've had HORRENDOUSLY
bad reliability problems with burned DVD media. This being from several
different brand discs, different burners, software, PCs and even
locations.
Seems a good many discs just don't want to let you record multi-gig files
onto them. Well, they'll let you RECORD but you're screwed if you want to
read them back whole. And I'm talking about storage intervals of
sometimes
less than ONE MONTH! This in a controlled temp/humidity environment.
It's
bad enough that I've gone back to TAPE.

Note, I'm talking about DVDs here, not CDs. I've had better luck with
CD-R
media, but they're not large enough to hold the files involved (large
.tar.bz archives of XML data)

-Bill Kearney


Density. The DVD format is much more dense, so any bleeding of the dyes in
the media, and you can easily be beyond the error correcting code facility.