Charts new and old.

[Oceanride007]

First an observation that I am a little worried about.
Observation, it seems that older charts have much more information regarding detail close to the shore. So much more information relevant to small boats. New surveying pays particular regard to depths around 30' to reflect the deeper draft vessels and show next to "not much" outside likely shipping route.

Back in 2008 I sailed up the Red Sea as crew, the skipper had some old fathom "British admiralty" photocopied charts he had obtained by chance. Of course these charts are dated and the coral may not be where it was, but the detail was immense and of great value as we had to avoid the poor vis of open water as eyeballing ships was difficult.

I can see a need to access the same info on a chart plotter, as secondary information.

But the point is these charts should be scanned while they still exist. Soon very soon the only charts that will be ECDIS and port authority. There is a wealth of info that will be lost if they are not scanned now, I do not think any Hydrographic office would release less than the latest charts. The losers will be the sailing community only.

I can see legality is a issue, but I think if these were made available like guidance notes should be OK. I have some from a dodgy Russian site years ago, I would like a more reliable access to info in the future, & small scale.

Any answers! perhaps you would like to submit URL of internet sites that do this already, USA is covered quite adequately I think.

[Mainebristol]

Interesting.

There is a common trap that is developing, and I am afraid that the price will be paid in boats.

The earth is an irregular illipsoid, which means that most surveys upon which charts are based, are off,... by some minor degree. Therefore when a chart shows you great detail, particularly when the chart is not attached to a continent, (the Marshall Islands, for example) GPS's can show great detail - which is in the wrong place.

The fault does not lie with the Gps, or the charts. Rather, the fault lies with the datum, and sometimes the survey from which the charts were created. Always, always look at the legend of a chart. You might just be surprised at how old the information is from which the chart is derived. Of course, with a GPS chartplotter, that information might not be available at all. I wonder how many sailors know that they are navigating by GPS in tight, tight quarters using information surveyed in the nineteenth century?

[Nicholson58]

Originally Posted by Mainebristol

Interesting.

The earth is an irregular illipsoid, which means that most surveys upon which charts are based, are off,... by some minor degree. Therefore when a chart shows you great detail, particularly when the chart is not attached to a continent, (the Marshall Islands, for example) GPS's can show great detail - which is in the wrong place.

The fault does not lie with the Gps, or the charts. Rather, the fault lies with the datum, and sometimes the survey from which the charts were created. Always, always look at the legend of a chart. You might just be surprised at how old the information is from which the chart is derived. Of course, with a GPS chartplotter, that information might not be available at all. I wonder how many sailors know that they are navigating by GPS in tight, tight quarters using information surveyed in the nineteenth century?

SO TRUE:

Everyone who seriously cruises/transits should take a charting course. I think I have seen YouTube and/or Wiki articles on charting and how & why our charts are off.

There are areas along the S American coast where your GPS will show you 4 miles inland. On these charts where the background was obtained from 18th, 19th & 20th century sextant readings the errors can be particularly large the farther you get from Greenwich. (or well traveled commercial routs). Many of these surveys are over 150 years old and long overdue for re-do. As you pointed out, this ancient background chart, (the only chart) is what is used as the seed file on everyone's GPS chart plotter.

As far as old charts go, open sea charts and charts of durable coasts might be cautiously usable. I have several charts from the harbors of Muskegon, Holland, Grand Haven, (Lake Michigan). No sane person would navigate with these. They are better as historical documents for use by folks doing 20th century archaeology. Some are beautiful but look like they were done by Father Marquette. In some cases, the rivers have moved well away from the old chart shape, position, depth. Hold the new & old charts against a lighted window and see that there is little resemblance.

[Oceanride007]

OP here. I'm talking about admiralty charts that precede modern color charts, many soundings, views of distant hills from a certain point at sea, sometimes contour lines of hills, towns . I learn't navigation by sextant, I know caution is required, I know how to geo reference but probably choose not to. The point is these charts were first created by the British admiralty sunk huge resources in obtaining the info (even financed Charles Darwin voyage), then others and more than 150 years of successive hydrographers and improvement, now because commercial shipping who bankrolls much of this activety is not interested in many of the details that we are still interested in and digital memory was tight for a while, that info has been deleted.
One day the GPS satelite array may fall to earth. You may very well want as much info again. Just suggesting saving the info, to an extent we have been hijacked by the GPS, and it may not always be there. And like I say esp in regard to Red Sea, it would be very beneficial to some mariners now.

[Oceanride007]

Bounce.

[Nicholson58]

007 - can you post some images? Your description reminds me of the 1900's vintage engineering drawings in the vault where I used to work. Back in the day, they were inked on rag velum. Trees, shrubs bricks and people were rendered in perfect detail.

Just remember that once the gloss is stripped away from that piece of art, the chart is rendered in raster or vector format and sold to us as gospel reality.

[goboatingnow]

Originally Posted by Oceanride007

OP here. I'm talking about admiralty charts that precede modern color charts, many soundings, views of distant hills from a certain point at sea, sometimes contour lines of hills, towns . I learn't navigation by sextant, I know caution is required, I know how to geo reference but probably choose not to. The point is these charts were first created by the British admiralty sunk huge resources in obtaining the info (even financed Charles Darwin voyage), then others and more than 150 years of successive hydrographers and improvement, now because commercial shipping who bankrolls much of this activety is not interested in many of the details that we are still interested in and digital memory was tight for a while, that info has been deleted.
One day the GPS satelite array may fall to earth. You may very well want as much info again. Just suggesting saving the info, to an extent we have been hijacked by the GPS, and it may not always be there. And like I say esp in regard to Red Sea, it would be very beneficial to some mariners now.

Most of these old charts contain data and views that are totally out of date. There use is more as an historical artefact then marine chart.

Charts have nothing to do with GPS location. They made be now created with precision GPS location techniques, but it doesn't require GPS to use modern charts.

The GPS array ( not to mention several other gnss arrays) isnt going to " fall " out of the sky. And if t does, the worlds problems will be far greater then you worrying about chart accuracy

Dave

[Suijin]

I think much of that particular change is due to a change in the responsibility, resources, and methodology of charting agencies. They're not going to include information that they can't confirm on newer charts and so it gets eliminated.

This probably varies country by country. Here in the states, NOAA, the organization responsible for surveying and producing charts, is probably underfunded. I live in the Chesapeake Bay much of the year, and pretty much everything outside of the main channel up to Baltimore has not been surveyed since WWII. That's right, the majority of one of the most trafficked stretches of water in the old wealthy U.S. of A. has not been updated in over 75 years.

There is a point on the Chesapeake at the entrance to the Choptank River that on Navionics charts was until recently about 1/4 mile east of it's true position.

Go outside of the main channel in the Chesapeake and you should not trust that anything marked as two fathoms or under is going to be accurate. I know that because I've run around in two fathoms of charted water a whole bunch of times. As they saying goes, there are two kinds of sailors on the Chesapeake; that that have run around and those that are lying.

[Oceanride007]

To N58 I don't have any old charts of this type, just memories of them. These charts were used by most of the worlds merchant fleet, they were pretty good for a coastal fix and provide info for the mariner should they be adrift and needed to calculate the risk, ships were much more unreliable.

To GoBo many sailboats are running up on coral in the pacific due to reliance on GPS plotter and vector. Distant hills with high point or even contour was handy for LoP and haven’t moved, Corals are pretty slow. A few more raster would help.

To Suikin Its easy to be accurate when you don’t put in the detail. I suspect detail is removed and what remains is easily checked or reliant on old survey.

I think in European and US waters your coastline is pretty well known and an older chart wouldn't be of much value. The UK hydrographic office was active in charting the world for more than 100 years. My example was the Red Sea area, these older charts are of potentially immense value, on that voyage we also used as satellite image that we anticipated we would need, but no good for routing.

Anyway, I think given response thus far, its too late.
Marine charts only have a finite life of just a few corrections then the responsible authority says enough and does a updated chart, ships cannot keep uncorrected charts on board. Charting agents would be the same.

I have a few raster I got for free, perhaps I want more at much the same price. I wish for a legal repository of similar sailing direction items. Anyway my predecessor hunted down those old fathom charts he must have assessed there value. In my opinion the old charts he got were of much more value than a modern chart for our intended voyage and cheaper.

[bobconnie]

For one thing, theres some info on old charts you don't find on the new ones paper or electronic. Things like fishing info, bottom material, anchorages that seem to be missing on new ones ! stuff like this is important enough to me for me to keep my OLD charts even though I have new paper and electronic! There have been times I made a harbor the old way when my stuff took a dump in the fog ! Just sayin, it's to bad they quit putting stuff like that on the new charts, even though they are so much more accorate !

[carstenb]

Originally Posted by Mainebristol

Interesting.

There is a common trap that is developing, and I am afraid that the price will be paid in boats.

The earth is an irregular illipsoid, which means that most surveys upon which charts are based, are off,... by some minor degree. Therefore when a chart shows you great detail, particularly when the chart is not attached to a continent, (the Marshall Islands, for example) GPS's can show great detail - which is in the wrong place.

The fault does not lie with the Gps, or the charts. Rather, the fault lies with the datum, and sometimes the survey from which the charts were created. Always, always look at the legend of a chart. You might just be surprised at how old the information is from which the chart is derived. Of course, with a GPS chartplotter, that information might not be available at all. I wonder how many sailors know that they are navigating by GPS in tight, tight quarters using information surveyed in the nineteenth century?

nineteenth century is actually quite new for some charts. Danish waters were extensively charted in the 1860 & 70's, so about 150 years ago. They were charted by sailing a grid 100 meters apart, casting the log and getting bottom samples.

What's between he 100 meter soundings? Your guess is as good as anyone else's. The Danish maritime authorities are now recharging using side-scanning sonar, but they're not throwing lots of resources at it. And they are doing the commercial channels first.


Out in the pacific - most charts, in use today (also on the fanciest chartplotters) were made by captain cook or the like, say 300 years ago.