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Old 06-01-2015, 01:11   #61
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Re: Another foundering how do chart plotters get it wrong

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Originally Posted by Mirage Gecko View Post
In my opinion in this case near Gull Island it was human error.
As to the OP most of my boating has been done on the Qld coast and the Barrier Reef.
Many years spent with charts only scratching around reefs etc off Nth Qld with eyes peeled on the water after consultation with the charts.Personally I am now much more comfortable on the water with the electronic aids available to me as opposed to just charts.
My personal observation of the electronic charts and GPS units is that they are rarely more than metres in error be it signal or chart fault.
I certainly am not able to compete with that by paper charts alone.
Frankly I am continually amazed at their acuracy especially relative to sand banks,reefs and channel markers etc I am personally very familiar with.
Although we own one more boat than I need we still charter a bit and the management of that company continue to tell me that most of the groundings of their boats happen due to complacency of experienced skippers.
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That's my limited experience too.

However, events of recent times with experienced crews with capable vessels running aground on clearly marked obstacles, led me to ask the question. Why are they doing it?
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Old 06-01-2015, 01:57   #62
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Re: Another foundering how do chart plotters get it wrong

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Originally Posted by Rustic Charm View Post
That's my limited experience too.

However, events of recent times with experienced crews with capable vessels running aground on clearly marked obstacles, led me to ask the question. Why are they doing it?
Nothing new to any of this.... they may be experienced 'racers'.... experienced navigators? Probably not....

Back before GPS.... late 80's or v early 90's .... the day job...poking along in northern Bass Strait at about 02dark and keeping a listening watch on 16/12 ...paraphrased a bit but pretty close to what occured....this is what I heard...
' Lonsdale light this is yacht 'Trump Card'
'Go ahead'
'We are in the West Channel and have anchored next an oil rig...where are we'
'I don't know where you are but there aren't any oil rigs in the West Channel'

further chatter ensues..

Then Melbourne Radio VIM buys into the act...

'Trump Card... what does this oil rig look like?'
'Oh... lots of bright lights and three big towers sticking up in the air'

' You are next to a Maersk jack up which is anchored off Cowes, (Phillip Island, Westernport)'

a pause...

'Oh ... I think we must have hung a right a bit early... we will go out and have another shot at it when the sun comes up....' ( that bit is close to verbatum)

Anyone knowing this area will understand how truly remarkable that feat was... the rest of you can crack open OpenCPN and go have a looksee.

Nothing new under the sun........
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Old 06-01-2015, 02:27   #63
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Re: Another foundering how do chart plotters get it wrong

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Nothing new to any of this.... they may be experienced 'racers'.... experienced navigators? Probably not....

Back before GPS.... late 80's or v early 90's .... the day job...poking along in northern Bass Strait at about 02dark and keeping a listening watch on 16/12 ...paraphrased a bit but pretty close to what occured....this is what I heard...
' Lonsdale light this is yacht 'Trump Card'
'Go ahead'
'We are in the West Channel and have anchored next an oil rig...where are we'
'I don't know where you are but there aren't any oil rigs in the West Channel'

further chatter ensues..

Then Melbourne Radio VIM buys into the act...

'Trump Card... what does this oil rig look like?'
'Oh... lots of bright lights and three big towers sticking up in the air'

' You are next to a Maersk jack up which is anchored off Cowes, (Phillip Island, Westernport)'

a pause...

'Oh ... I think we must have hung a right a bit early... we will go out and have another shot at it when the sun comes up....' ( that bit is close to verbatum)

Anyone knowing this area will understand how truly remarkable that feat was... the rest of you can crack open OpenCPN and go have a looksee.

Nothing new under the sun........
that's so funny.
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Old 06-01-2015, 04:04   #64
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Re: Another foundering how do chart plotters get it wrong

Perhaps my earlier post wasn't explicit enough. There is simply no good reason for these folks to have been within five miles of Gull Island in the dark (as they must have been to hit it at 0500). Any prudent navigator would not have pushed the limits of accuracy by attempting to pass close to these hazards.

This accident can't be attributed to charting errors or instrument errors -- it was due to human errors of judgement.

Jim
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Old 06-01-2015, 04:29   #65
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pirate Re: Another foundering how do chart plotters get it wrong

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Originally Posted by fjwiley1 View Post
Hey Boatman.......you and Mark J are really doin good......i had to give up my Mk 1 eye balls for the Mk 1 Mod 2 Eyeball,,,getting older.....but they still work good.

Life is good if you Keepa Smilin.......




Sent from my iPad using Cruisers Sailing Forum
Ahahahahahahaaa... hanging in there.. just..
Still don't need the 'Far Lookers' but the 'Close Lookers' are getting serious use these days..
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Old 06-01-2015, 04:47   #66
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Re: Another foundering how do chart plotters get it wrong

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Originally Posted by Jim Cate View Post
Perhaps my earlier post wasn't explicit enough. There is simply no good reason for these folks to have been within five miles of Gull Island in the dark (as they must have been to hit it at 0500). Any prudent navigator would not have pushed the limits of accuracy by attempting to pass close to these hazards.

This accident can't be attributed to charting errors or instrument errors -- it was due to human errors of judgement.

Jim
I don't think anyone would doubt that Jim. not even them. I was just using this case to introduce the topic.
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Old 06-01-2015, 05:49   #67
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Re: Another foundering how do chart plotters get it wrong

EVERYONE here should know that hazards actually move under the cover of darkness.... Daylight puts them in their proper place....


Quote:
Originally Posted by boatman61 View Post
Ahahahahahahaaa... hanging in there.. just..
Still don't need the 'Far Lookers' but the 'Close Lookers' are getting serious use these days..
HA!!!

Reminds of a limited visibility night passage through a shipping lane one time.... TWO guys could not read the bearing range on the tiny plotter....

soon after... "close lookers" went into the crewing kit...
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Old 06-01-2015, 14:38   #68
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Re: Another foundering how do chart plotters get it wrong

Years ago when I was a coppa, (that's Bill to you poms and bacon I think to you Yanks), I attended to a guy who had fallen out on to a jetty after ramming his runabout. He insisted it (the peer) wasn't there when he launched it. I breathalysed him and he was pretty full, but due to some technicality in those days he didn't get convicted. Breathalyser boaters was not that common then.

I also remember a drunk driver that parked his car half way up a power pole, insisting it jumped out in front of him and he was just taking avoiding action.
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Old 06-01-2015, 15:40   #69
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Re: Another foundering how do chart plotters get it wrong

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Originally Posted by Jim Cate View Post
Perhaps my earlier post wasn't explicit enough. There is simply no good reason for these folks to have been within five miles of Gull Island in the dark (as they must have been to hit it at 0500). Any prudent navigator would not have pushed the limits of accuracy by attempting to pass close to these hazards.

This accident can't be attributed to charting errors or instrument errors -- it was due to human errors of judgement.

Jim
Agree. GPS Accurately places your boat on the earths surface. Charts were created with vastly inferior plotting devices I.e. Sextants. And DR
Both GPS and Sextants have the same intent, correctly placing a boat on the earths surface. Sextants and hence charts created by Sextants can be wrong by an amount. Pick a number 1,2,3,10 NM? Rely on paper charts at your peril.
If there is a dangerous object shown on a chart give it a wide wide berth.
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Old 06-01-2015, 15:53   #70
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Re: Another foundering how do chart plotters get it wrong

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Comments:

ON my copy of the relevant chart, the survey date is shown as 1970. This is before GPS was used in surveys. Absolute accuracy is not likely.
Is 1970 the date given in the little box in the corner of the chart or just the date under the title? ( away from my paper charts just now). When they first metricated Oz charts they would simply say 'from the latest info available..blah blah' then they took to putting the little detailed boxes in the corner. Case in point was the Gulf of Carpentaria... the old fathoms chart used to say... 'from the work of Matt Flinders...1810 (or thereabouts)'... went metric and then said 'latest info'...was still matt flinders stuff.

Much of the northern coast ( within a few miles of the land) of Tasmania was surveyed using 'lines of soundings' in about 1947. Plenty of chance to miss something between the lines esp in an area like that. Nothing whatsover to do with GPS, electronic charts or anything else...simply quality of the original survey.
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Old 06-01-2015, 16:15   #71
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Re: Another foundering how do chart plotters get it wrong

And also... much of Bass Strait and thereabouts further off shore has been surveyed with 'lines of soundings' dating from the 1800's. The lines of soundings were quite clear on the old imperial charts but not so obvious on the metric charts.

Re 'Trump Card'... also returning to Port Philip from Hobart... I reckon it was one of the most amazing feats of navigation since Noah made landfall on Mt Ararat. To the left is where they thought they were.... on the right was their actual position. How they did it without losing their yacht remains one of the great unsolved mysteries of the sea....
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Old 06-01-2015, 16:18   #72
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Re: Another foundering how do chart plotters get it wrong

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And also... much of Bass Strait and thereabouts further off shore has been surveyed with 'lines of soundings' dating from the 1800's. The lines of soundings were quite clear on the old imperial charts but not so obvious on the metric charts.

Re 'Trump Card'... also returning to Port Philip from Hobart... I reckon it was one of the most amazing feats of navigation since Noah made landfall on Mt Ararat. To the left is where they thought they were.... on the right was their actual position. How they did it without losing their yacht remains one of the great unsolved mysteries of the sea....
I can't see how they were in any danger?

I just can't understand how you can make that sort of mistake.
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Old 06-01-2015, 16:20   #73
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Re: Another foundering how do chart plotters get it wrong

This is a good article on Australian charts.
It seems to me that the official advice is the best advice.

Make sure you have paper charts.
Don't rely solely on electronic charts, nor solely on paper charts.
Keep a look out
Keep a distance.

= seamanship.

My Sailing: All you've ever wanted to ask the Hydrographic Service
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Old 06-01-2015, 16:43   #74
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Re: Another foundering how do chart plotters get it wrong

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Is 1970 the date given in the little box in the corner of the chart or just the date under the title? ( away from my paper charts just now). When they first metricated Oz charts they would simply say 'from the latest info available..blah blah' then they took to putting the little detailed boxes in the corner. Case in point was the Gulf of Carpentaria... the old fathoms chart used to say... 'from the work of Matt Flinders...1810 (or thereabouts)'... went metric and then said 'latest info'...was still matt flinders stuff.

Much of the northern coast ( within a few miles of the land) of Tasmania was surveyed using 'lines of soundings' in about 1947. Plenty of chance to miss something between the lines esp in an area like that. Nothing whatsover to do with GPS, electronic charts or anything else...simply quality of the original survey.
It has everything to do with GPS, Paper Charts, Electronic Charts and Original Survey plus 1947 soundings.
The paper Chart is a mixture of Captain Cooks efforts, sounding in 1947 and other verified sightings. This info/data, with all its errors, is combined into a paper chart. This paper chart morphs into an electronic chart (including all the errors accumulated in the last 200 years).
A chart plotter displays this chart with pretty colours and icons. THEN we overlay a totally accurate GPS reading of our boats position. So we now have an accurate location placed on inaccurate charts. Pick a number. Captain Cook's calculations were not accurate. Pick a number 1,2,3,10, NM error.
If there is a rock or reef is on the chart then it most likely does exist....EXCEPT it could be 1-10 NM nearer or further to you actual correct position provided by the accurate GPS set of satellites. .........give any sharp hard object on a chart a very very wide wide berth. The only other accurate item on your boat is the depth sounder.
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Old 06-01-2015, 16:46   #75
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Re: Another foundering how do chart plotters get it wrong

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It has everything to do with GPS, Paper Charts, Electronic Charts and Original Survey plus 1947 soundings.
The paper Chart is a mixture of Captain Cooks efforts, sounding in 1947 and other verified sightings. This info/data, with all its errors, is combined into a paper chart. This paper chart morphs into an electronic chart (including all the errors accumulated in the last 200 years).
A chart plotter displays this chart with pretty colours and icons. THEN we overlay a totally accurate GPS reading of our boats position. So we now have an accurate location placed on inaccurate charts.
cheers, now that answers well my original intent of how it's happening.
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