Death to PAPER ! More Nails in the Paper Chart Coffin . . .

[osirissail]

Originally Posted by doug86

Perhaps you should modify that to say "stand alone chart plotters generally only display Vector charts, and cannot show the detail....". . .

Yes, quite correct. If you are able to display raster charts then, in essence you are using "paper charts."

[smurphny]

I have three different chartset/software systems that I've experimented with : Sailcruiser, on laptop which uses C-Map charts, Garmin chartplotter, which uses its proprietary charts, and Sea Clear also on laptop which uses Raster charts (Sailcruiser will also function w/ rasters). I have used these all both aboard and in planning. Question: these different nav systems, using the same waypoint coordinates, the same courses will return slightly different locations on-screen. What do you think would be the most likely reason for these discrepancies? Things like this make me very hesitant to put much faith in using GPS technology for anything requiring more than general-area location. When lat/lon is constant, graphic location should be the same regardless of chart systems.

[hummingway]

It could be a pixel resolution issue I suppose.

[MarkJ]

Originally Posted by smurphny

What do you think would be the most likely reason for these discrepancies?

I agree. Thats why I don't use a sextant. 3 stextants lined up on deck and what do you get?

3 differnt answers.

And 'Navigators eye' where you get a blind spot from retina burns from accidental exposue to the sun.

With GPS one doesn't get 'Square Eye' because the screens are rectangular.

[donradcliffe]

The CP's with raster charts don't always give the same answer as paper. CP's and GPS's are not idiot proof, and you should always use all the information available to confirm them. If all the inputs don't agree, you had better slow down and stop to figure out what is wrong before you get into trouble.

Once I was approaching Grand Canaria on a delivery, and the landmarks didn't agree with the CP. I used the CP like a paper chart, and safely reached the marina. Checking things out, it turns out the owner had been in Croatia and had reset the GPS to the Croatian one, which was 0.6 miles off. Once I reset things to WGS84, everything lined up.

For myself, I have 4 laptops, each with OpenCPN and 29,000 charts (think of how much they would cost in paper), plus 4 GPS recievers. During lightning storms, a laptop and 2 GPS's go into the oven.

I am a bit embarrassed to find that the only paper charts I have with me are for more than 4,000 miles away--I haven't used paper charts in over a year, but think I'll get one paper chart of the Hawaiian Islands when I get to a chandlery. I also store GPS waypoints for my potential destinations before I leave on a passage. You really don't need any charts when you are out on the open ocean--most passagemakers used plotting sheets in the old days. I log my position twice a day in case I need to haul out the sextant.

I agree that the guy who charted Vanuatu was a drunk. Most paper charts are consistently off, but the charts of the Banks Islands have different errors depending on which side of an island you are on. Google earth may not be foolproof, but its probably a lot better than the some of the official charts.

However, going down the Cape Cod Canal, if you are off by more than 20 feet, something is seriously wrong with your CP/GPS.

[roger.waite]

Used in isolation, every technology can invite us into nature's recycling systems. Eyes, ears and paper charts also have shortcomings, esp. at night.

Shortcomings seldom matter until we assume our mental picture is more accurate than it is, or rashly go close to known and unknown hazards.

I use Google maps to plan. Perhaps I will put some on a plotter? I would use them (with 'all other means') in locations where I trusted charts less.

While reliance on chart plotters seems a tad OTT to me, I carry one and use it in unfamiliar or complex areas. A simple boat has its own merits ... but some boats are always traveling in unfamiliar or complex areas.

My ramblings, FWIW

[smurphny]

Originally Posted by donradcliffe

However, going down the Cape Cod Canal, if you are off by more than 20 feet, something is seriously wrong with your CP/GPS.

That's what one would think but it was with the Garmin chartplotter, with their charts, waypoints laid in ahead of time, not with some self-calibrated chart. It is a very reliable little unit which is normally very accurate and has worked very reliably before and since. Its anchor alarm is on every night on the hook and detects any slippage immediately. Maybe there is some sort of signal interference in the CC Canal. BUT, this is exactly why I would never rely on GPS as a sole means of nav. Inaccuracy is understandable when trying to use beta versions of some calibration software on a .jpg image but errors like this using expensive proprietary gear leads me to take any info coming in over GPS with a BIG grain of salt.

That said, having dealt with the progression of electronic navigation since the days of Rdf, GPS is certainly wonderful when trying to cross Block Island Sound in the fog!

GPS/Jeppesen is my main source of nav. charts but I also have a little printer on board with which to make printed charts. It's really handy because it allows printouts at whatever magnification is best. Most times the whole unwieldy chart is not necessary.

[GordMay]

See Dacust’s excellent treatise on the subject of electronic chart accuracy:
“ERRORS ON MARINE NAVIGATIONAL CHARTS”

Inland Waters Resources - Chart Errors

“… With paper charts you will not automatically know where you are. You have to use various means to determine that. Like taking compass bearings from shore objects. This may seem like a disadvantage, and to some extent it is. But if the chart is off, then let's say you use a GPS to get your exact position. You plot that on the chart. Since the chart is off, you have now plotted your self in the wrong position in relation to the chart. That's the trick. You don't care exactly where you are, you only care where you are in relation to the shoals and rocks. That's how you use paper charts. If there are any relational errors, they probably are not a problem if you are sticking to main channels. These charts were most likely done by mariners who made sure the important stuff was right. So, relational errors are usually only a factor if you are approaching a shore that a ship would not normally approach. Then you use a little more caution. But you always have to keep in mind that the bottom may have changed. Someone may have put in a new jetty. A new light may have been installed. This is why it is critical to keep up-to-date charts. The positional accuracy may not be improved in the latest chart, but the new light should be there.

Electronic charts are mostly made from the paper charts. Even the pretty vector charts. So they have all the same possible errors as the paper ones! But they have more. As stated above, if the chart is off positionally, the GPS will faithfully plot you within 10 meters of the exact place on Earth where you are. But since the chart is off, you know exactly where you are by the numbers, but you don't know where the underwater rock is by the numbers. You only know where it is in relation to the point and the island.

If you are going to use electronic charts, you MUST know what the possible errors are and how to deal with them.

The only time you can totally trust a GPS is:
You have been that way before and saved the track (“been there“ waypoints & tracks).
While saving the track, you kept watch on what the GPS is reporting as its accuracy.
You also have a 3d type depth finder so you know that not only did you not run into anything, but it was clear for a reasonable distance on either side (or you know the waters well enough).
While you follow the track back out, you keep an eye on the GPS reported accuracy to make sure it is capable of keeping you close enough to your track to be safe.

In other words, the only time you can totally trust a GPS is when you are using it independantly from the charts. You can trust a GPS when comparing it to data from a GPS (or to itself), but not in relation to a chart …”

See also “Behind the Accuracy of Electronic Charts”
Behind the Accuracy of Electronic Charts

[doug86]

Gord,
The first two sentences of Dacust's treatise say it all: "With paper charts you will not automatically know where you are. You have to use various means to determine that."

That was the point of my post #293; that it is ridiculous to put a sign on a chart plotter that warns "Not to be used as a sole means of navigation" when such a sign would be just a valid on a paper chart, or even a single floating navaid.

Dacust explains how one might be better off not knowing one's exact LAT/LON on the earth, and for coastal navigation, you're better off fixing your position correctly with reference to surroundings of the paper chart. This is true, but as he points out, it is so because of inaccuracies of the chart to begin with, not do to inaccuracies of the GPS system. This thread is about the future of paper charts, not the past.

As time goes on, the inaccuracies of the paper charts will diminish, as the cartographers all use GPS and satellite photos to update all the data on charts. It is my understanding the the USCG now places all floating navaids with a GPS, not in reference to a paper chart.

Coastal plotting uses various methods of dead reckoning to get a position. Deck reckoning pilotage always starts with an assumed position. Why not just start with the GPS position as one's assumed position and work from there?

Accurate coast piloting also requires one to know what speed over the ground one is making. I can't think of a more accurate device to determine that than a GPS.

gotta go! more later

[ActiveCaptain]

From my experience, there's always the same or greater error in paper charts as compared to electronic ones. The major difference is that my electronic charts are always more up-to-date and have a chance of being more accurate. Making hand compass readings and plotting them to make sure you're in the correct relative position isn't more accurate than GPS positioning today. Actually, the hand plotting is much more dangerous because of the time it takes to do it and the error that is easily introduced. There's no way I'd ever want to be doing hand position plotting while moving down any channel - it's silly to suggest that anyone does this today (or should) unless they're in a predicted log race.

I think there's a much bigger change going on with electronic charting and the future of what we'll use for navigation. For slightly offshore and offshore charts, the existing charts are pretty good. If someone's there to keep up with new obstructions that might come up because of manmade structures, the combination of "Google Earth" with existing electronic charts is perfect for recreational cruising.

For inland/near coastal use, the future is in crowd-sourcing of the depths. I'm working with 2 companies now who have both created prototypes of this. As helms become more connected, your depth data will be collected and uploaded to a central server. That server processes the raw data against the current tide level, wind effects, and transducer placement to provide it to the people behind you (directly behind you or people on the same path next week). The charts you'll use will have various ways of displaying this data to show what you can expect along particular paths. If you contribute to the data upload, the "charts" are free or subsidized. If you don't upload the data as part of the community, then you'll pay full price for the data.

None of this is speculation or hypothetical. It's happening right now.

Right now, electronic charts are just static images. They're more up-to-date than the paper charts but there's not much that takes advantage of the potential of the electronics other than automatic GPS plotting. The next phase will by dynamic electronic charts that are constantly changing. When that happens, I'll bet there will be threads like this where people will explain why the new, dynamic charts aren't as good as the old electronic ones. Change isn't ever simple or quick.

[osirissail]

Getting back to the principle topic - Death to Paper (charts) it is a natural progression. First all charts - paper or raster/vector digital all originate from the "acetates" or originally drawn paper chart stored in the bowels of the governmental cartographer's lair. Although I suspect even the original acetates are being replaced by a digital version that is guarded and kept "backed up" to prevent loss. Changes are made to it and then a copy is made accessible to the public or commercial subscribers.
- - What will probably change is the access to physical paper charts by the public. Right now, chart stores are converting to the "chart on demand" systems where they do not have to keep an inventory of physical paper charts - which with time get out of date and/or never get sold. Instead they have large printers that directly access via data links, the government's original and then print that out for the customer.
- - Purveyors of digital charts do basically the same thing, access the latest governmental version of the chart and then convert that to the digital raster or vector format for inclusion in their product which is sold to the customer.
- - Physical storage requirements of paper charts is a major factor in their demise. They take up too much room on board and are a considerable "dead weight". A large amount of charts can be stored on CD or hard drive. Then - if you have the software and a printer - you can print out a "hard copy" for use if desired yourself.
- - From Active Captain: "The next phase will by dynamic electronic charts that are constantly changing. When that happens, I'll bet there will be threads like this where people will explain why the new, dynamic charts aren't as good as the old electronic ones. Change isn't ever simple or quick." - - As the saying goes: The constant in this world is change.

[hogfighter]

As a military / airline pilot who has used GPS since, well, the beginning, here's what I learned regarding chartplotters:

The coordinates provided from the GPS are, practically speaking, always correct.

The Chartplotter's really cool color chart (fundamentally the same as we had in the F/A-18 30 years ago) may, or may not, be accurate. In other words, that channel marker may (or may not) be exactly where it is displayed on your digital chart. But if you have correct coordinates for the same marker, displayed as a waypoint, it will always be displayed with a high degree of accuracy.

In summary, GPS is correct, while the folks at Garmin, Raymarine, etc. are not always.

[smurphny]

Originally Posted by ActiveCaptain

For inland/near coastal use, the future is in crowd-sourcing of the depths. I'm working with 2 companies now who have both created prototypes of this. As helms become more connected, your depth data will be collected and uploaded to a central server. That server processes the raw data against the current tide level, wind effects, and transducer placement to provide it to the people behind you (directly behind you or people on the same path next week). The charts you'll use will have various ways of displaying this data to show what you can expect along particular paths. If you contribute to the data upload, the "charts" are free or subsidized. If you don't upload the data as part of the community, then you'll pay full price for the data.

None of this is speculation or hypothetical. It's happening right now.

Right now, electronic charts are just static images. They're more up-to-date than the paper charts but there's not much that takes advantage of the potential of the electronics other than automatic GPS plotting. The next phase will by dynamic electronic charts that are constantly changing. When that happens, I'll bet there will be threads like this where people will explain why the new, dynamic charts aren't as good as the old electronic ones. Change isn't ever simple or quick.

The crowd sourcing aspect of this is really interesting. IMO, charts should be free. They are funded by taxpayer dollars wherever they are produced and are, quite simply, a safety item. Governments are quick to implement new rules and regulations in the name of safety but, except for the limited US coastal NOAA charts and some Brazilian charts, refuse to release chart info. to the public domain which would benefit the idea of safety as much as any regulation. Sooner or later the information will be freely available through this merging of Google Earth and information compiled by the boating public. Companies that are charging astronomical prices for charts will have to come down to earth, competing on quality of product not taxpayer gathered but "secret" information, withheld under the guise of copyright.

[jackdale]

A couple of comments:

Until I find a chartplotter that does not put me on land when anchored stern-to in Princess Bay on Wallace Island, I will be using paper charts and traditional navigation methods in close quarters.

BTW, I teach electronic navigation, but only after my students have a understanding of how to read a chart, tide and current tables, Chart 1, etc., as well as plot a position, lay out a course and account for set and drift.

I will always remember overhearing a conversation on the VHF as I was getting ready to go around Whale Cay in the Abaco's in 1992. One of two other boats (who were travelling in company) would not go around because his GPS had quit and he did not know where he was.

The crowd sourcing is an interesting idea. My concern regarding depths is that in some areas with extensive eel grass and other weeds, depth sounders will give false readings. In Sidney Spit I always verify my depth with a lead line.

Which chart datum would be used? Canada and the US use different ones. This might actually lead to everyone using lowest astronomical tide, which until now has been impossible as all paper charts would have to be reprinted.

[s/v Jedi]

Originally Posted by jackdale

Until I find a chartplotter that does not put me on land when anchored stern-to in Princess Bay on Wallace Island, I will be using paper charts and traditional navigation methods in close quarters.

So.... with paper chart, pencil, clock and sextant you can plot your position with greater accuracy than a chartplotter with gps? Because that is what you're suggesting here, right?

You must mean that you will use eyeball navigation or radar or some other method useful for close quarters. All of these work just as well combined with a chart plotter than they do combined with a paper chart.

ciao!
Nick.