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Old 15-03-2009, 04:37   #136
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Mark makes a good point about technology in that the most progressive future thinkers would embrace new technology not shun it. I am sure that they would also be well aware that all systems are limited are prone to errors.

We should not be relying 100% on any data or at least know that it could contain errors and we might have to look at the data differently or use work arounds.

Digitized data available today seems more robust than the "technology" limited to cramming data onto a printed page.

CAD drawing certainly has given designers powerful tools, but it takes a different kind of mastery than does a pencil, triangle, T square and compass. In technical drawing CAD (digitized) drawings are superior to hand drafted ones in accuracy. Some older folks resisted the move, but soon CAD will be universal and all those drafting tools will be only seen in museums. I see the same future for navigation. It's not quite here yet though.
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Old 15-03-2009, 10:06   #137
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In Cook's own time he wasn't best known for his navigation, but for his exploration. And within nautical circles - primarily naval at that time, and he was a Royal Navy officer - he was considered a genius for the health of his crew. Iirc he lost only one sailor to scurvy in his three voyages of exploration, an astonishing feat at the time and of far greater importance to the war-standing navy than his scientific or even his cartographic endeavors.

Were he alive today he'd likely be in academia rather than afloat since we now more generally fund research.
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Old 15-03-2009, 12:01   #138
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My first Navigator once told me that "Successful navigation is not about knowing where you are but definitely knowing where you are not" As he leaned over and crossed out an area on the chart he said " and we are definitely not - there"
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Old 15-03-2009, 12:20   #139
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This all reminds me of a cocktail time story I heard:

This shiny powerboat comes into the PLC marina and the skipper/owner turns out to be of the loud kind. As he joins the crowd at the bar that night, a conversation about the best GPS is heating up. He listens and next remarks that all their GPS'es are crap. When asked why that is so, he replies: You're all exchanging waypoints and calculating new ones using charts; none of that is needed with my GPS because it came with all the waypoints already programmed in there. When I left Miami, I just scrolled the list and found the PLC waypoint (Venezuela) and selected it. The autopilot took over and here I am!!

I hope everyone can see the joke in that one and I'm still not sure it's just a funny story or if it really happened ;-)

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Old 15-03-2009, 12:57   #140
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Time to Catch a Breath

This thread has shown prolonged interest and high enthusiasm. Posts have varied between those who emote well but have little knowledge or experience to experienced navigators, schooled in the traditional means of positioning, reluctant to let go of tried-and-proven methods.

There's absolutely no question that electronic charting is here to stay, and to it's advantages over paper charts.

I believe it would be useful to review for a moment how electronic charts are made, and what they fairly represent.

RASTER charts are simply snapshots of paper charts. They contain EXACTLY what the paper charts contain, both the good and the bad. They look exactly like the paper charts they derive from, because they ARE simply digital reproductions of those paper charts. In every aspect.

VECTOR charts are another matter altogether. They are not all created equal, by any means. Perhaps the best ones are those made by governments, such as the NOAA ENC charts. Here's what NOAA has to say about their vector chart production:

Quote
NOAA ENC is a vector database of chart features built to the IHO's S-57 standard. NOAA's Office of Coast Survey, as the U.S. national hydrographic office, is exclusively responsible for production and authorization of NOAA ENC data in U.S. waters.

NOAA ENCs support all types of marine navigation by providing the official Electronic Navigational Chart used in ECDIS and in electronic charting systems. NOAA ENCs support real-time navigation, as well as the collision and grounding avoidance needs of the mariner, and accommodate a real-time tide and current display capability that is essential for large vessel navigation. NOAA ENCs also provide fully integrated vector base maps for use in geographic information systems (GIS) that are used for coastal management or other purposes.

Building and Maintaining NOAA ENCs
In 1997, NOAA began a process of building a portfolio of ENCs that encompass the same areas covered by NOAA’s suite of approximately 1,000 paper and raster charts. The ideal and most accurate way to build ENCs is to recompile the paper chart from all of the original source material. Unfortunately, this process is impractical as it is far too labor intensive. Instead, NOAA ENCs have been compiled from source on those features that are deemed to be navigationally significant. U.S. Army Corps of Engineers' federal project limits have been captured from large-scale drawings. These precise coordinates of channel limits are being incorporated into the ENC. Likewise, high-accuracy positions are being used to chart U.S. Coast Guard aids to navigation. The paper chart has been the source for the remainder of items.
NOAA has utilized private contractors to build NOAA ENCs. Private companies are provided high-resolution source information such as U.S. Army Corps of Engineers channel limits, and aids to navigation established by the U.S. Coast Guard. Contractors are also provided with the latest version of the paper/raster chart. All NOAA ENCs that are built by private contractors are reviewed by NOAA cartographers before they are posted on the Internet.

NOAA cartographers and private contractors (under NOAA supervision) apply updates to ENCs using high resolution original source material. As new source information arrives at NOAA headquarters, cartographers update NOAA ENCs using high resolution position and depth information.
Unquote (bold emphasis added)

MidlandOne is correct when he says that ENCs are built from a vector database. That is, when they are built by governments. However, not all vector charts are built this way. Some, published by independent companies, utilize in whole or in part charts which have been digitized from paper charts. This process is one which is akin to tracing an outline through paper, using an electronic pencil. Depending on who's doing the tracing, and how they feel that morning, the results can be quite accurate or they can be way off in some places.

Further, while vector charts sometimes include data to a greater depth than do paper charts, they typically lack the information on shore-based features which can be very helpful to the mariner who knows how to use them.

What's true of both types of electronic charts -- raster and vector -- is that their depiction of the real world may contain significant errors, both of omission and of comission. Features may be omitted. Features may be misplaced. Spelling errors abound in vector charts, less so in government-produced raster charts.

Enter the GPS. When it's working well -- which is 99% of the time or more -- it will yield a reliable Lat Lon readout, with an accuracy measured in feet. The chartplotter will take this reading and plot it on the chart.

Voila! There you are. Or, at least, there you think you are on the chart. Much of the time you may, indeed, be where shown on the chartplotter. But, some of the time, you won't be. You won't be because the chart itself is in error. Raster or vector. Rarely, you won't be because the GPS is in error. Yes, it happens. A few years ago aircraft crossing the Atlantic were showing GPS positions about 300 miles north of their positions. Timing error from the GPS satellites. Software glitches can occur. Murphy can intervene (don't ever forget, that little sucker is always aboard, lurking about and looking for ways to wreak havoc on your sensible and ordered world).

And, as noted several times above, lightning and other electrical difficulties can render your gps and/or your chartplotter useless -- for a few minutes or forever, depending.

What's all this mean?

To me, it means that the prudent mariner will use GPS, chartplotters, electronic charts, and ALL OTHER MEANS AVAILABLE to determine his position, and to navigate carefully. Including, inter alia: the Mark #1 eyeball, sometimes assisted by a good set of 7x50 binoculars. Paper charts. Fathometer. Radar. Smells and sounds. Sixth sense (informed and experienced intuition).

When something doesn't seem right, it often isn't, despite what the chartplotter may say.

Don't be lured into a state of electronic hypnosis. Use your senses, all your navigational tools and, most of all, your brain.

Even in 2009 with all the marvelous electronic wonders available to us, navigation remains a fine art, comprised of both science and informed judgment.

Bill
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Old 15-03-2009, 14:06   #141
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Originally Posted by btrayfors View Post
This process is one which is akin to tracing an outline through paper, using an electronic pencil. Depending on who's doing the tracing, and how they feel that morning, the results can be quite accurate or they can be way off in some places.
I agree, but this is mostly the same for the government charts. The only difference is that they use an alternate source for inland channels (Army) and buoys/markers (CoastGuard). All other features are taken from the paper chart! So it all comes down to quality control and supervision.

Quote:
To me, it means that the prudent mariner will use GPS, chartplotters, electronic charts, and ALL OTHER MEANS AVAILABLE to determine his position, and to navigate carefully. Including, inter alia: the Mark #1 eyeball, sometimes assisted by a good set of 7x50 binoculars. Paper charts. Fathometer. Radar. Smells and sounds. Sixth sense (informed and experienced intuition).

When something doesn't seem right, it often isn't, despite what the chartplotter may say.

Don't be lured into a state of electronic hypnosis. Use your senses, all your navigational tools and, most of all, your brain.
Exactly, and this is where the new generation (anyone who started navigating with GPS or even plotters) of navigators is at an disadvantage. Those of us who had to do without the electronic positioning HAD to do all that Bill wrote above. I remember the value of radar upon landfall... we used it to determine our position and I always had to grumpily admit I was a couple of miles off...... again ;-) But before that, when we couldn't afford the radar or just didn't have it because "that ain't for yachts", it always took a lot of time to determine exact position upon landfall... all those capes look very much alike from miles offshore. Remember counting them? or estimating their relative distance from the boat? In the end, you still wasn't 100% sure when you started approaching closer, but as more details became visible, like houses etc. more confidence was build until you got that "now we're sure" marker or building in sight and checked it's bearings. All the time leading up to that moment you were "walking on egg shells", examining the waves ahead for possible shallows/obstructions etc.
Now I see myself sailing over the chart on a LCD display; but I still look for that rock or reef for confirmation and am even worried when I can't find it (still too far away), sometimes making course changes to create bigger margins until I get a visual and correct course again. I don't see many new-generation navigators do that... not enough.

cheers,
Nick.
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Old 15-03-2009, 15:38   #142
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Thanks for the rational voice Bill.

I like paper charts for one other reason. I have never heard of anyone having a a screen on their boat as large as a paper chart. As my eyes get old I can't read as well as I used to. It is much easier on my eyes to study paper charts than computer screens. I am not a ludite. I like E charts but also like paper charts. If I could only have one I'm not sure which I would chose. I guess that decision would depend on where I was sailing. For US waters I would think that E charts would be fine.

In the US paper charts are not too bad. I've got a chart book that costs me aroudn $50 and gets me from SF all the way just south of Ensenada Mexico. I spent $300 on used E chips that get me all the way from Alaska thru Mexico. I keep my eye open for charts on ebay and other places and manage to find them pretty inexpensive. The Brits have their charts copyrighted and that makes for much more expensive charts.

Right now I have both. I will trade, copy, or buy paper charts for everywhere that I go.
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Old 15-03-2009, 15:41   #143
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I use a system that I started when gps first came out and have used it now for about 17 years. I make a note of the lat/long of all the compass roses on all my charts and put them into my H/H gps then when sailing I set the go to function to go to the closest comas rose. This gives me a distance and bearing to that compass rose. At any time I can see the distance and bearing to that rose and then take my piece of makralon (3cm x 50cm) I mark of the distance from the lat on the side of the chart on the plastic. then put the point of the deviders on the centre of the rose and slide the plastic against the devider point and turn the plastic untill it passes through the bearing. then mark the possition from the end of the plastic this gives a possition on the chart. This can be done in about 15 seconds when you are used to doing it. I hope this is clear as I find it easier to show this method than to explain in writinf. I will have to try to make a video of it

I really like this combined use of paper and GPS.
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Old 15-03-2009, 17:42   #144
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Of course one of the downsides to GPS / Chartplotters is that the Govt can track where you are and where you have been.........and insurance companies. A year or two back saw a local powerboat with a decent sized hole in his bow. Boat on Autopilot with GPS found the waypoint. spot on. marked by a navigational bouy Fortunately a floating one..........but in the interests of fairness I should mention that many years ago pre GPS someone using a paper chart did nearly run into a similar bouy in thick fog. Always claimed that one for perfect navigation - ignoring the previous half hour of "thinking aloud"

As in much else in life, it's not simply about the equipment you have - but how you use it
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Old 15-03-2009, 19:00   #145
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I'll just add here that I use GPS and paper charts. I don't have a chart plotter, although when I get bored one day I might wire up my GPS to my laptop or something of the sort.

I like paper charts because I can make notes on them, it's a better view of an island or coastline, and you can use two line of sights as a confirmation in addition to GPS.

All in all I've just never gotten into the chartplotter thing. Everytime I hear of some guy who gets lost or slams into something he/she was typically using a chart plotter. I know there are some awesome sailors that use electronic gadgets, but I'm not aware of any terrible sailors that use paper charts and can operate a sextant. Food for thought.
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Old 15-03-2009, 20:40   #146
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I like paper charts because I can make notes on them, it's a better view of an island or coastline, and you can use two line of sights as a confirmation in addition to GPS.
If you were to get yourself an Electronic Charting System program for your PC you will find that you will be able to do all of those things, plus much, much more, all faster and much more easily than on paper. You will find that you can do everything that you can on paper plus more.

As the years have gone by the more and more posts I see from those who have various excuses for not using electronic the more I see that many just do not understand what it can do for them . Of course people can use whatever they like and some will prefer the old methods just for the fun of it, just as happens with other things, but that is not often the excuse given.
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Old 15-03-2009, 22:25   #147
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Of course one of the downsides to GPS / Chartplotters is that the Govt can track where you are and where you have been.........and insurance companies.
Well not directly, only if they have physical access to your GPS receiver and it had track logging enabled. A GPS receiver is just that - a receiver, not a transmitter - the satellites not only don't know where you are, they have no idea you exist.
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Old 16-03-2009, 02:40   #148
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Many of the replies to the thread including myself only suggested paper as a back up. Unfortunately a couple of electronic no matter what posters labelled us anti electronic, living in the past etc. As I have already pointed out I use electronics 99% and charts only as a back up or if my eyes suggest a double check. Secondly most on this site sail around North America using NOAA derived data. The problem is in many parts of the world the source of the data is poor and out of date. While I am sure US electronic charts are very accurate would you be as confident say in Tonga. In Tonga we were advised to get hold of Moorings Charter charts as they were deemed the most accurate. It is very expensive to gather vast amounts of data and many countries do not have the funds to allow the accurate data to be gathered. Australian Hydrographic charts are also very accurate except in some northerly areas MarkJ take note. As for Indonesia and South East Asia generally?
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Old 16-03-2009, 03:54   #149
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While I am sure US electronic charts are very accurate would you be as confident say in Tonga.
Well, I would be equally confident of the official electronic charts for Tonga as I would be of the official paper charts .

Why do I say that? Well, the official electronic charts for Tonga are RNC's (raster navigation charts) and are therefore EXACT COPIES of the official paper charts with no possibility of difference.

In that case it is not an issue specific to the electronic charts that one needs to be concerned about, it is prudence with respect to the accuracy of the hydrographic data that the official paper charts are based upon that is required as the errors in the paper charts are exactly reproduced on the RNCs and the RNCs will have no other errors apart from those.
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Old 16-03-2009, 04:22   #150
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Well, I would be equally confident of the official electronic charts for Tonga as I would be of the official paper charts .

Why do I say that? Well, the official electronic charts for Tonga are RNC's (raster navigation charts) and are therefore EXACT COPIES of the official paper charts with no possibility of difference.

In that case it is not an issue specific to the electronic charts that one needs to be concerned about, it is prudence with respect to the accuracy of the hydrographic data that the official paper charts are based upon that is required as the errors in the paper charts are exactly reproduced on the RNCs and the RNCs will have no other errors apart from those.
You are a goose! You cannot read or understand what has been written. Does the fact that I have stated that the Moorings charts are supposed to be more accurate than the official charts not say that they are all unreliable paper or electronic if based on paper charts?
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