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Old 09-01-2015, 06:02   #121
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Re: Another foundering how do chart plotters get it wrong

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Originally Posted by carstenb View Post
It has been noted that chartplotters allow the unwary to go further to sea. I beive this to be a truism. Before plotters became everymans toy, going to sea (or sailing at all) required having a knowledge of charts, ow to read them and how to interpert them. Acquiring this knowledge meant becoming aware of what was shown on the chart............
Yea, we should not use those newfangled chart plotters. Real mariners use paper charts (and sextants, lead lines, etc.)

Probably the biggest advantage of a chart plotter is that it doesn't just display and scroll the chart, it shows exactly (within a very few feet) where your boat is on the chart.

For those who want to cling to the old difficult ways, by all means use your paper charts and don't waste your money on chart plotters depth sounders, etc. For the rest of the folks, a good chart plotter makes it easier and safer to go boating. You still have to learn things but it's much easier and the result is the same, safe passage from X to Y.
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Old 09-01-2015, 06:05   #122
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Re: Another foundering how do chart plotters get it wrong

Ron

Don't get me wrong - I have a chartplotter and use it. I think plotters are wonderful and opened up sailing to many that would not have done so if faced with paper charts, dividers, pencils and sextants.
But there's a lot to be said for being able to use DR and the old ways of navigating - it gives you a better feel for what's going on.
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Old 09-01-2015, 06:25   #123
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Re: Another foundering how do chart plotters get it wrong

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Probably the biggest advantage of a chart plotter is that it doesn't just display and scroll the chart, it shows exactly (within a very few feet) where your boat is on the chart.
Well, there's the rub...

Call me old-fashioned, but I'd prefer to know where I am in the Real World...

:-))





That's the great danger, of course, how easily what one sees on these amazing devices becomes conflated with geographic reality... This pic gives a more accurate representation of where my boat was actually situated, at the time... :-)


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Old 09-01-2015, 06:50   #124
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pirate Re: Another foundering how do chart plotters get it wrong

Going through the Kanakale the CP had the boat travelling along ridges up to 1km inland...
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Old 09-01-2015, 07:36   #125
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Re: Another foundering how do chart plotters get it wrong

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Originally Posted by carstenb View Post
It has been noted that chartplotters allow the unwary to go further to sea. I beive this to be a truism.
Sextants, Loran, GPS, fiberglass, dacron, small diesels, compact compasses, roller furling, radios, weather forecasting, and many other boat-specific things also allowed this with their respective introductions.

History is very long with "old salts" complaining about advances letting "newbs" go to sea.

Question: Should AIS not be allowed until people can prove that they can calculate changing crossing vectors of many ships simultaneously using only paper charts, a handheld compass and pencil?

Mark
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Old 09-01-2015, 07:37   #126
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Re: Another foundering how do chart plotters get it wrong

It's not just people on boats who over rely on what their GPS tells them!

8 drivers who blindly followed their GPS into disaster - The Week
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Old 09-01-2015, 07:43   #127
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Re: Another foundering how do chart plotters get it wrong

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Well, there's the rub...

Call me old-fashioned, but I'd prefer to know where I am in the Real World...

:-))

That's the great danger, of course, how easily what one sees on these amazing devices becomes conflated with geographic reality... This pic gives a more accurate representation of where my boat was actually situated, at the time... :-)
Of course, Jon. But that doesn't change whether you have paper or electronic charts.

I can just as easily turn this around on you and show you the respective paper and electronic versions of the area we are currently in. The paper version is quaintly hand-drawn using data acquired before your grandma was born, while the electronic version is pretty good, although one must still use their eyes.

And you are blaming your failure to use the correct tools on newfangled "electronics".

You do know it is stupid easy now to quickly make a google earth overlay of any area on earth you wish to travel, don't you? Heck you can even store GE data in cache and make charts at any time without an internet connection. If you smile and wave, you may even see yourself on the chart...

Mark
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Old 09-01-2015, 07:45   #128
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Re: Another foundering how do chart plotters get it wrong

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Going through the Kanakale the CP had the boat travelling along ridges up to 1km inland...
Where did your position on the paper chart put you?

Did it take all your accumulated navigational knowledge to keep the boat off the land?

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Old 09-01-2015, 07:51   #129
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pirate Re: Another foundering how do chart plotters get it wrong

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Originally Posted by colemj View Post
Sextants, Loran, GPS, fiberglass, dacron, small diesels, compact compasses, roller furling, radios, weather forecasting, and many other boat-specific things also allowed this with their respective introductions.

History is very long with "old salts" complaining about advances letting "newbs" go to sea.

Question: Should AIS not be allowed until people can prove that they can calculate changing crossing vectors of many ships simultaneously using only paper charts, a handheld compass and pencil?

Mark
Rather use my eye's and brain to calculate angles/speeds and any course changes than miss things running up and down checking AIS and chart.. been crossing the English Channel that way for over 30yrs.. and its quieter these days than in the 60's, 70's, '80's and 90's...
Nothing against 'Noobs' to the fleet.. the 'Wrinkly Old Salts' are just as bad.. but its easy to be seduced.
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Old 09-01-2015, 07:55   #130
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Re: Another foundering how do chart plotters get it wrong

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H If you smile and wave, you may even see yourself on the chart...

Mark
Not unless you are getting your satellite feed from the NRO!
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Old 09-01-2015, 08:04   #131
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Re: Another foundering how do chart plotters get it wrong

Here you go Jon - for next time you visit.

BTW, it doesn't even appear you chose good charts. Here is the CM93 chart for your area.

When I look at the electronic raster charts, I see these details also.

I don't think these failures on your part should constitute damning of electronic charts and charting in general.

I must admit, though, if you look closely you will see that the electronic chart is off by a couple of feet. Damn those electronic charts!

Mark
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Old 09-01-2015, 08:08   #132
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Re: Another foundering how do chart plotters get it wrong

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Originally Posted by Jon Eisberg View Post
Well, there's the rub...

Call me old-fashioned, but I'd prefer to know where I am in the Real World...
OK you're old fashioned!

If you're out of sight of land or even out of sight of landmarks, you don't really know where you are in the "real world".
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Old 09-01-2015, 09:08   #133
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Re: Another foundering how do chart plotters get it wrong

Near shore navigation relying solely on a chart plotter is risky business. Chartplotters are like any other computer. Garbage in garbage out. Many surveys are very old and done by human beings with varying amounts of skill and sobriety.
I'll take a glance at a Chartplotter to verify what I already believe to be true, but that's where it stops.
I don't even have a Chartplotter on my sailboat, just an old lat/long only GPS.
All kinds of things can affect accuracy of survey information, aeration in the water, weeds, rocks, dead heads, faulty equipment, improper use of equipment.
Then there's the false sense of security that comes with Chartplotters. Would you even consider making landfall on a dark hazardous, isolated, unfamiliar coast without a chart plotter? Just your naked eye, some sailing directions and a magnetic compas?
No? Well then you shouldn't do it with a Chartplotters either.

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Old 09-01-2015, 10:14   #134
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pirate Re: Another foundering how do chart plotters get it wrong

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Originally Posted by colemj View Post
Where did your position on the paper chart put you?

Did it take all your accumulated navigational knowledge to keep the boat off the land?

Mark
Triangulating on landmarks using Mk 1/chart data works extremely well.. even at night.. pretty accurate.
Only started using CP's since 2012 when buying Nimble Navigator for a Pacific delivery to Perth was a lot cheaper than all the charts I'd need..
Prior to that 90% of my experience was Trans-Atlantic-W Europe and the Med.. for that it was GPS-Chart-Depth-Mk1 and past experience.. aka local knowledge..
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Old 09-01-2015, 11:14   #135
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Re: Another foundering how do chart plotters get it wrong

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Triangulating on landmarks using Mk 1/chart data works extremely well.. even at night.. pretty accurate.
Only started using CP's since 2012 when buying Nimble Navigator for a Pacific delivery to Perth was a lot cheaper than all the charts I'd need..
Prior to that 90% of my experience was Trans-Atlantic-W Europe and the Med.. for that it was GPS-Chart-Depth-Mk1 and past experience.. aka local knowledge..
Triangulation on landmarks works even better with electronic charts because you can easily draw and move bearing lines.

I suspect if you took your GPS position and transferred it to a paper chart, you would have the same relative fix as the electronic, no?

It is as easy to not run one's boat 1km inland using electronic charts as it is with paper charts, isn't it?

One can use local knowledge, depth, past experience, et al with electronic charts as with paper, can't they?

Understand that I am not questioning your experience or knowledge, just that you seem to be making remarks about electronic charting/charts that are no different than with manual charting/charts.

If you need to impugn electronics, you need to do much better.

Mark
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