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Old 14-03-2009, 19:36   #121
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MarkJ - just found better deal Endeavour Navigator Australian chart set for $745 and you can buy the software $450 upwards. My mate MidlandOne says this is the way to go, chuck your Maxsea overboard or in my direction please. I know you and most that read this forum are on a tight budget but our Kiwi based sailor knows all. Sorry could not help myself its Sunday a time to relax and enjoy the crap that eminates from across the pond
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Old 14-03-2009, 19:38   #122
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This particular error affecting only a limited set of objects on a limited set of charts, and even then only with a limited set of chart viewers.

Most likely, this was only a few older viewers with newer charts. I dunno precisely. On the other hand, I do know such errors are rare but not unknown in most any application with a very large number of data sources.

Which is why one should not rely on any single source of information while navigating, in my personal opinion.
I Agree - which is why I suggested carrying paper charts as a back up many posts ago
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Old 14-03-2009, 19:38   #123
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Regarding being fair to C-Map I can only see them becoming even better in the hands of Jeppeson given their long and well regarded experience with aviation charts and publications. Maybe they are the charts to aim for if selecting a new pleasure plotter.
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Old 14-03-2009, 19:45   #124
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One thing no one has said in support of charts is they are only as good as the quartermaster who maintains them. Charts do go out of date as soon as you get them if you don't maintain them. Naval QMs dedicate a lot of time reading "Notice to Mariners" monthly publication or free online for chart updates. Its part of the shipboard planned maintenance system (3M) or what ever its called now. If you pull your charts out now and you dont have cutouts from the NTM scotch-taped or annotated on them then youre not maintaing your charts. Its the same as not changing engine oil or swabbing your decks.

As for chart plotter accuracy it varies depending on where you are. Though the USAF says they turned off Selective Availability in 2000 they still have the ability to vary your signal accuracy when ever they feel a need to do so. Like when the President is in town. They can do this with within very small areas.

Also do you have a differential GPS( If i remember correctly) with the ability to set a known fix on the chartplotter (like you know exactly where your dockside is as a benchmark) Even with GPS the Navy still corrects their plotters and SINS to a known benchmark as part of any pre-underway. The navigation team runs a system of cross plotting from GPS/SINS/SONAR/BOTTOMCONTOUR(the military has amazing bottom contour charts)/VISUAL and other inputs to come up with a fix. They never rely on one input to derive a position. Plus most QM have a seperate diary/notebook of where theyve been with personal notes on Pilots/tugs/hazards and other things that are not on a chart. So when they go back they open it up and see who theyve used before.
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Old 14-03-2009, 19:48   #125
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MarkJ - just found better deal Endeavour Navigator Australian chart set for $745 and you can buy the software $450 upwards. My mate MidlandOne says this is the way to go, chuck your Maxsea overboard or in my direction please. I know you and most that read this forum are on a tight budget but our Kiwi based sailor knows all. Sorry could not help myself its Sunday a time to relax and enjoy the crap that eminates from across the pond
There is no need to chuck MaxSea overboard as you claim if that is what one has and one wants to go the way of official electronic charts. MaxSea supports both official raster (ARCS, so at least UKHO's charts) and ENC's (S-57).

I did suggest you might like to check what other ECS's did have such support but it seems you did not take that advice before jumping into the quicksand .
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Old 14-03-2009, 20:12   #126
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It's been established that the charts in whatever medium are inaccurate. The electronic charts are either scanned paper charts or digitized paper charts so it introduces another layer of error. It may not be much but we are dealing with some primitive technology in map making and much of those charts date back to the 19th century or or older I suppose.

The GPS position as a lat lon is probably quite accurate and capable of measuring tiny changes in faults so it must be capable of enough precision to navigate a vessel.

What we need to get is a GPS survey of all coast lines and maps created from that data. I suppose that the could then do a GPS survey of the bottom as well as Nav Aids but this would require constant updates as "things move" and I am not talking tectonic plates here.

Nav Aids should have AIS type beacons which report their current position, not where they were supposed to be. This would alert the coasties as well as mariners who assumed they were on station when in fact they have moved.

We are really living in a bizarre world as we "transition" from old hand made maps and charts, to digitized GPS surveys. A GPS plotter today has one foot in the old world and the other in the new world. We can see how powerful GPS plottings can be and how useful, but we can also see how reliable paper charts are where you rely on traditional skills to navigate.

I learned the old way and that gives me comfort and I carry papper charts and do (offshore) maintain a pencil track of positions. I do have several GPS with different chart so I can pick the one I like the best, so to speak and have some redundancy including a handheld which does not rely and the house electrics. Actually all the plotters do but with solar the chance of not having enough current to fire up a GPS for a fix is pretty slim.

But I have seen how one can't rely on the GPS plotters for positions, when the underlying charts are not correct. I was anchored on a mountain in Moustique years ago. However, in the waters where I am mostly naviagating these days, they are quite accurate as far as I can tell. But I have not updated the charts since I got them machines 8, 4 and 2 years ago.

I am looking to the day when our navigation is internet linked and the devices we use receive automatic updates of the charts in the background of course, seamlessly. It's only a matter of time before this happens... but the genius need to figure out a way to get inexpensive internet to the entire planet obviously wireless/satellite based. Once this happens you have weather and more real time anywhere.

In my life we have gone from some basic paper charting - to land based Loran and now to sat based GPS with digitized charting and now the internet has become like oxygen - we can't live without it and it enables and enhances everything.

And why can't we print a paper chart from a GPS plotter? It would seem that this too is very acheivable with printer drivers and small color printers.

I expect to see this all before I die as the changes are coming fast and furious as computers get more powerful and smaller. Soon will have both feet in the future... ands will still be travelling by the wind blowing big rags. hahahaha
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Old 14-03-2009, 21:09   #127
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...The electronic charts are either scanned paper charts or digitized paper charts so it introduces another layer of error.
That is not so.

The first claim might be so for raster charts but certainly is not so for vector and ENC's. Taking an official hydrographer's charts as an example (because official hydrographers produce both paper and electronic charts so we can use them for comparison, whereas off hand I don't know of any unofficial supplier that does) the data for all charts types will come from the same hydrographic database. In the case of their ENC's (that is their vector charts) the use of that data is in no way linked to any paper chart - they are produced quite independantly but drawing from the same wider database so to speak.

If there is an error or omission in the hydrographic database then that will be reflected across all chart types whether paper or electronic. However, it is usual for ENC's (and vector generally) to contain a far greater depth and breadth of information than paper charts do and so are more informative. That is possible because one can manage the depth and type of information on the navigation display so that clutter does not overtake their readability. It therefore stands to reason that they may contain more errors than the others just by the fact they have more information for errors to occur in, but that does not infer that they are less reliable insofar as the common information between the chart types is concerned.

Also, a powerful safety feature of vector/ENC's is the ability they give navigation displays to issue warnings about charted features or the mariners own highlighted areas or features if they are approached by the vessel. Just one example, the mariner may set a safe depth contour of 10m and the navigation display will announce (often with a voice message) an alert or critical warning if a lesser depth appears in the vessel's set look ahead zone. One can see that these abilites are also completely unrelated to paper (or raster) charts so don't come from paper.

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...And why can't we print a paper chart from a GPS plotter? It would seem that this too is very acheivable with printer drivers and small color printers.
It is quite usual for electronic charting programmes available to the pleasure market to print out that part of the chart on the display with no problem at all. One can also cut from the screen and create image files (eg jpegs, for other use eg for display on a PDA or to email, etc).

With respect to updating of official charts it is now pretty much as you wish for - of course you need to have the facilities and the money to access reasonably fast internet from wherever one is so is beyond the abilities of smaller boats and budgets unless close to land. I update my own charts from the boat with corrections and new issues when required when in range of cellular data but that is not done in the background, of course. However, it is much easier than downloading the Notices to Mariners and updating paper charts manually - a task I suspect very few relying on paper charts actually do.
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Old 14-03-2009, 21:38   #128
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Midlandone - thank you for the lectures I am so much more informed know that I have been so lucky to be able to read your great works.
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Old 14-03-2009, 22:22   #129
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Midlandone - thank you for the lectures I am so much more informed know that I have been so lucky to be able to read your great works.
It has been my pleasure. It is always good to get positive feedback, it makes it all worthwhile.
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Old 14-03-2009, 23:14   #130
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were they say you are on land, when indeed you are at sea, problem is the datum does not match
Or the chart is wrong. The people who surveyed the area for the chart didn't have a gps and mis-calculated the position. This is often the case.

But I have seen the datum error too, like a wgs-84 chartpack with some charts still at their original datum. The latest I saw was that they now corrected to wgs-84 datum but didn't update that in the chart attributes so that these still state that the chart is in another datum. This is even worse because now I don't know what's wrong anymore.

What I prefer for coastal sailing: seeing myself moving on the plotter's screen and the overlayed radar image lining up with the chart! Now I can always place myself on the chart, something you can't rely on with the paper chart on the knees. Also, I can still see if/when depths don't match and can slow down etc.... but I now know for sure that the depths on the chart are incorrect, while you wonder if you are somewhere else than you originally thought. You place too much trust in the paper chart in that case because you can't take the risk that the depth on the chart is right... you're not sure. Radar gives you that assurance and that's why it's excellent for sailing coastal waters in which one is not familiar.

I agree that paper backup is needed in case electronics fail. A good pilot book or cruising guide can do that in most cases.

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Old 15-03-2009, 01:50   #131
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As an amateur who is returning to the sea after spending a decade and a half on dry land I thought it prudent to read some on the subject. Presently I'm with Eric and Susan Hiscock as they approach Fiji on their second circumnavigation, circa 1959, sans GPS, sans radar, sans depth sounder, sans VHF, sans EPIRB, sans autopilot. Their only navigation equipment it seems consists of a compass, a sextant, an array of charts and piloting volumes including sight tables, a mechanical timepiece, barometer, anemometer, a distance logger, an AM radio, and two pairs of eyes.

What fascinates me is how they manage to make safe landfall after safe landfall with little to no concrete knowledge of the potential obstruction hazards that lay ahead. Though they brought with them over three hundred charts and volumes of pilot data, Eric Hiscock points out inaccuracy after inaccuracy in all of these. Often the charts displayed reefs not sighted since the 1800s, annotated with phrases such as "position doubtful".

And yet, knowing these hazards (though perhaps not precisely where they lie), they thought nothing more of the matter but to apply principles of good conservative seamanship to achieve their desired navigational objectives.
The point that has gained traction with me is that good seamanship dictates that one must develop a sense and respect for the unknown, that one should clearly understand the limits of his or her own abilities and the abilities of the crew, and that one must plan and execute passages such that these limits are respected, always.

If this rule holds fast, then a lack of concrete navigational resources becomes simply another matter which the skipper weighs when judging the prudence of the next course change. Advanced charting technology becomes merely an avenue upon which one may rely to make safe navigational decisions more quickly than is possible by more traditional means of fixing, like astronav for instance. For commercial operators time is money. And money is the reason they are at sea to begin with. Like other technologies introduced to the world to "save time," electronic charting simply reduces the coursing workload so passages are faster, or so that more duties can be piled onto the navigator to fill his "free time." (I don't mean to sound cynical, sorry)

It seems though that if the rules of basic seamanship are neglected however then not even today's most advanced navigation equipment could save the ship. Do you think a time will come when we can go a decade without a major shipping loss? A year perhaps?
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Old 15-03-2009, 02:05   #132
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Advanced charting technology becomes merely an avenue upon which one may rely to make safe navigational decisions more quickly than is possible by more traditional means of fixing,

Yes. and with the amount of time it frees up one can do many things not available in 1959. (Wheres that breadmaker thread?) Including enjoying the bloody passage
I am not denigrating the achievement of using the historical equipment and note the joy its bringing you, shown in another thread. But I don't for a moment think that if Eric & Mrs H were doing it now she, at least, might enjoy a watermaker shower, and a cooled G&T on deck instead of scribbling down Erics shouted sextant observations.



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Do you think a time will come when we can go a decade without a major shipping loss? A year perhaps?


Of course not. To err is human.

And I love our allowance to make a mistake.

Oops!





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Old 15-03-2009, 02:20   #133
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Don't think that I would ever put to sea without such modern conveniences like an autopilot, GPS or iPod. I'm simply attempting to reconcile the notion that relying on more modern means of passagemaking means less reliance on skills that have served mariners well for some time, with an erosion of those skills the result. A good mariner is not one to frown on a good idea or method of doing things. If a newer, better way avails itself then good sense dictates its use. But it seems to me that there are some essential skills a mariner should possess to ensure safe passage should it all go wrong and the vessel be put back into "the age of sail" as it were. And it also seems to me that some modern means of navigation may serve at a temptation for some to put to sea without due regard to the maintenance of these essential skills.

Perhaps my own fear of putting to sea wholly unprepared for what awaits has shaded my comments on this matter in a more conservative light than necessary. But I do admire the mental discipline and fortitude necessary to navigate around the globe repeatedly by such archaic means as the Hiscocks did, and would consider the erosion of these qualities within the recreational maritime community a great loss.

And yes, of course they would have kept up with the times, I just haven't read those books yet
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Old 15-03-2009, 03:23   #134
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When US looked for ways of writing in space they spent lots of time and money coming up with a device, the Russians used the ever reliable pencil, think about it!
Urban Myth

They both started with Pencils - and then developed space pens.......because lead breaks off (and floats around) and so do shavings.

snopes.com: NASA Space Pen
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Old 15-03-2009, 04:05   #135
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Don't think that I would ever put to sea without ...iPod.
IPOD!!!!!!!!!!!!!!!!!! That LOUD music will send you bonkers!!!!

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reconcile the notion that relying on more modern means of passagemaking means less reliance on skills that have served mariners well for some time,


Yes, and thats the difficulty many have. Reconciling in their minds, the safe haven of what is good, and right, and proper... reconciling that something so crass than real knowledge is be better, faster and safer.

And that is where it is. Someone like Captain Cook - the worlds best navigator of all time - could be outclassed, out-navigated, out performed by some trailer sailor with a chartplotter and a few hundred dollars in chips.

But those that realise it will then sit back and allow their mind to pick up the next challenge.

If Cook was here today he would still be the most famous navigator... it would just be in a different way... maybe as the person who integrates it all so the planet, the satellites and the sailor in the middle knows all and knows all instantly.

Paper has never shown us all. Its doesnít even show me the roads on the land. It may show me "Build Conspic" but when I anchor I still can't find the chandlery.

A modern Cook may want to have the location of every McDonalds included.

Please keep the joy you are relishing with the knowledge of paper and the hand instruments, but also have a go with a chartplotter


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