Yellow buoys

Tranona said:
....., but many like myself also carry electronic raster charts which do have more detail ......
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Didn't this come up a little while ago? Someone saying there were data on raster missing on oesenc vector charts but was unable to actually come up with any examples. (there are one or 2 known errors known about which might have been fixed by now. )

Any examples of detail on raster missing from "quality" vector?
 
GHA said:
Didn't this come up a little while ago? Someone saying there were data on raster missing on oesenc vector charts but was unable to actually come up with any examples. (there are one or 2 known errors known about which might have been fixed by now. )

Any examples of detail on raster missing from "quality" vector?
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Agree- clearly one needs to zoom in and out using electronic vector charts to see full detail on a small screen (mine is 9 inch, smaller on iPhone, bigger on iPad (11 inches I think). I expect the perceived limitations of electronic charts are from the less digitally familiar users. In the future we may have chartplotters the size of paper charts !
 
dom said:
Is that conclusion consistent with the data? I don't think so.
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No, not true. The problem is twofold. First the source data is often unreliable, although for UK waters this is a minor issue in most parts of the country and second what you see, is determined by the compilers and the software with limited input from the user.

To illustrate the former. If you use C Map in the Ionian you will find quickly that entering Lakka (a popular place) your track will take you over the hill to the east of the actual entrance, through the school house and yard, but deposit you safely on the quayside. Fortunately when you leave you follow exactly the same route! Then move down to Fiskardo another popular place and entering the harbour is fine but as you zoom in your position changes and you end up moored in the middle of Tassias Taverna which has been in the same place on dry land since the 1760s!

The issue GHA alludes to can be found lower down in the thread on Garmin plotters which raises the way the submarine barrier off Portsmouth is shown. On some versions it seems not to show at all, on others like mine it is difficult to spot even at the right level of zoom because Garmin use a different symbol to the source and do not seem to include any details of what it actually is.

I have no doubt you could find many more examples of these problems and as I said earlier Antarcticpilot recently gave a much fuller explanation of the process used by chart compilers.

Most of us, though, particularly in familiar waters do not see these problems, and if used sensibly chart plotters are a significant contributor to ease of navigation. However if you are sailing in unfamiliar waters (as I found when I first sailed in Greece) they should be treated with extreme caution until you know the foibles.
 
Tranona said:
If you use C Map in the Ionian you will find quickly that entering Lakka (a popular place) your track will take you over the hill to the east of the actual entrance, through the school house and yard, but deposit you safely on the quayside. Fortunately when you leave you follow exactly the same route! Then move down to Fiskardo another popular place and entering the harbour is fine but as you zoom in your position changes and you end up moored in the middle of Tassias Taverna which has been in the same place on dry land since the 1760s!
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Brilliant ;) This should be lifted verbatim and added to every navigation course: racing and cruising alike!
 
capnsensible said:
Does this thread really demonstrate that you cant beat a proper pilot book, made of bookstuff....... ;)
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Not really. All it says is that no source of information is perfect or comprehensive, so you choose what suits you best and use it aware of its limitations.

So, planning my few days off later in the week I have my almanac, pilot and paper chart (Imray) at home (plus google for weather etc!). This will allow me to work out the basic shape of my passage plan, where I can go or not go and any critical points. So I will have a good overview in my head of timings, courses etc before I start.

Then will make basic notes for reference then translate the key information such as waypoints onto the chart plotter which I use to monitor progress.

Probably not a lot different from others who learned their navigation the conventional way.
 
Tranona said:
No, not true. The problem is twofold. First the source data is often unreliable, although for UK waters this is a minor issue in most parts of the country and second what you see, is determined by the compilers and the software with limited input from the user.

To illustrate the former. If you use C Map in the Ionian you will find quickly that entering Lakka (a popular place) your track will take you over the hill to the east of the actual entrance, through the school house and yard, but deposit you safely on the quayside. Fortunately when you leave you follow exactly the same route! Then move down to Fiskardo another popular place and entering the harbour is fine but as you zoom in your position changes and you end up moored in the middle of Tassias Taverna which has been in the same place on dry land since the 1760s!

The issue GHA alludes to can be found lower down in the thread on Garmin plotters which raises the way the submarine barrier off Portsmouth is shown. On some versions it seems not to show at all, on others like mine it is difficult to spot even at the right level of zoom because Garmin use a different symbol to the source and do not seem to include any details of what it actually is.

I have no doubt you could find many more examples of these problems and as I said earlier Antarcticpilot recently gave a much fuller explanation of the process used by chart compilers.

Most of us, though, particularly in familiar waters do not see these problems, and if used sensibly chart plotters are a significant contributor to ease of navigation. However if you are sailing in unfamiliar waters (as I found when I first sailed in Greece) they should be treated with extreme caution until you know the foibles.
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I would say the opposite - paper charts should be used with extreme caution. They are always out of date (unless you buy a whole set of new ones each year- I’m sure no leisure sailor does), they’re useless in the cockpit, useless when wet, they give no tide nor AIS data and can’t be used for easy as pie real time navigation!

Recently I sailed to the Scillies for the first time arriving (unplanned) after dark - this would have been more hazardous without a chartplotter/Navionics (with my level of skill), but was a totally relaxed experience.

Paper charts have one advantage - large FOV for route planning, but are otherwise inferior in every way (in my opinion!). My impression is that most sailors use Navionics (or equivalent) for 99% of navigation and rarely refer to paper charts.
 
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Giblets said:
They have one even bigger advantage - they work without power!
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Only during daylight hours!
And most of us carry multiple GPS devices with batteries so I doubt power ever a problem in reality. And most of the ‘paper is best’ brigade wouldn’t dream of setting sail without relying on a depth sounder which usually has no power redundancy :)
 
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Yealm said:
And most of the ‘paper is best’ brigade wouldn’t dream of setting sail without relying on a depth sound which usually has no power redundancy :)
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Really? Like almost all other sailors I carry a calibrated lead line and regularly use it - esp when swinging a new anchorage.

Last outing last week ;)
 
Yealm said:
Apolgies, I stand corrected! :)
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Seriously though, there is a risk of bananaing ones rudder in highly tidal anchorages like the Isles Of Scilly. The turning circle can be really quite large at low water. Same applies on the edges of rivers & creeks.

It's often useful to have a mosey about with the lead line from the tender, kayak, or whatever to get a feel for the bottom in terms of humps, bumps, rocks, detritus, shelving, etc. as low tide approaches.
 
Yealm said:
I would say the opposite - paper charts should be used with extreme caution. They are always out of date (unless you buy a whole set of new ones each year- I’m sure no leisure sailor does), they’re useless in the cockpit, useless when wet, they give no tide nor AIS data and can’t be used for easy as pie real time navigation!

Recently I sailed to the Scillies for the first time arriving (unplanned) after dark - this would have been more hazardous without a chartplotter/Navionics (with my level of skill), but was a totally relaxed experience.

Paper charts have one advantage - large FOV for route planning, but are otherwise inferior in every way (in my opinion!). My impression is that most sailors use Navionics (or equivalent) for 99% of navigation and rarely refer to paper charts.
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Why don't you read what I say instead of trying to rubbish it.

Each type of publication has its pros and cons and you need to be aware of them and use them accordingly. I never said I used paper charts for pilotage or active navigation, but just like you I use the paper chart to get an overall picture of the potential passage. As I explained I then check against other sources with particular attention to things to avoid and possible alternatives. I thought this was what proper passage planning was about.

So, using the example of the submarine barrier. If I was planning a passage from the east into Portsmouth I would have to consider it. The chart gives me a good picture of the problem and identifies a safe course to avoid it. Then I go to the Channel Pilot for a bit of background and find out that I can use the lit passage in certain circumstances so I have alternatives. When actually on passage I will be using the Garmin with appropriate waypoints - well aware that the barrier is not as clearly identified on the screen. However that is irrelevant as I already know (in my head and in planning notes) the effect it has on my course. If I chose the alternative passage I can use the Garmin to guide me as the marked and lit passage is correctly placed on the chart.

Those who rarely use paper charts are not using the full range of information available to them. In my view navigating by Navionics is like driving a car with a satnav - you can end up in places you did not intend - just as my examples of wrecked Clipper yachts illustrate.
 
Yealm said:
The Dodman yellows are clearly marked on my Garmin plotter :)
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But the pilot book, including in its ebook format, answered your opening post.

The prudent mariner uses all available resourses.

The physical pilot would clearly have been of more use to you, you couldnt get the electronic one.

Nobody uses charts in the cockpit........

Anyway, happy sailing!
 
Yealm said:
I would say the opposite - paper charts should be used with extreme caution. They are always out of date (unless you buy a whole set of new ones each year- I’m sure no leisure sailor does),
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Or you keep them up to date using notices to mariners. I think I know a few people who do that.

I also know lots who have very old charts in their plotters.
 
Tranona said:
Why don't you read what I say instead of trying to rubbish it.

Each type of publication has its pros and cons and you need to be aware of them and use them accordingly. I never said I used paper charts for pilotage or active navigation, but just like you I use the paper chart to get an overall picture of the potential passage. As I explained I then check against other sources with particular attention to things to avoid and possible alternatives. I thought this was what proper passage planning was about.

So, using the example of the submarine barrier. If I was planning a passage from the east into Portsmouth I would have to consider it. The chart gives me a good picture of the problem and identifies a safe course to avoid it. Then I go to the Channel Pilot for a bit of background and find out that I can use the lit passage in certain circumstances so I have alternatives. When actually on passage I will be using the Garmin with appropriate waypoints - well aware that the barrier is not as clearly identified on the screen. However that is irrelevant as I already know (in my head and in planning notes) the effect it has on my course. If I chose the alternative passage I can use the Garmin to guide me as the marked and lit passage is correctly placed on the chart.

Those who rarely use paper charts are not using the full range of information available to them. In my view navigating by Navionics is like driving a car with a satnav - you can end up in places you did not intend - just as my examples of wrecked Clipper yachts illustrate.
Click to expand...

The part of your post I disagree with was the bit about electronic charts being used with ‘extreme caution’, implying they are inferior to paper.
 
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