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Old 13-11-2017, 01:28   #1
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Another plotter assisted grounding?

There has been a few plotter assisted groundings discussed here recently.

Ok, I know its not a cruising boat.

There are lessons to be learned here for all of us.

My mail is that it ploughed into the reef doing the best part of 16 knots.

Substantial damage and crew shaken.

Towed to Cairns backwards.

Skippers blaming ECDIS.

The goss is the clown wasn't operating it correctly.

Anything to add.

See.....No Cookies | The Cairns Post
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Old 13-11-2017, 04:12   #2
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Re: Another plotter assisted grounding?

And your source for all of this conjecture is?
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Old 13-11-2017, 08:55   #3
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Re: Another plotter assisted grounding?

All I'm seeing from the article is that the Captain is blaming the ECDIS. If I ran aground I would be blaming something else too.
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Old 13-11-2017, 12:15   #4
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Re: Another plotter assisted grounding?

Chartplotters typically show different chart details at different magnifications (resolutions). Good navigators will keep varying the chart resolution to see what may not even be showing up at a different magnification level of that chart.

One cat that ran aground on a reef recently showed that reef on their chartplotter only at the highest resolution and they admitted that it hadn't been used.

The devil is in the details.
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Old 13-11-2017, 15:05   #5
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Re: Another plotter assisted grounding?

Hereís the rub... if you lay down a rhum line between two points and the line goes over an obstacle the chart plotter should really inform you of it - regardless of the zoom level. You should be able to set the width of the rhum line so it can pick up anything within a specified distance off the rhum line as well. You canít do anything about things that arenít plotted at all but it would at least take care of the silliness that zooming is.
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Old 13-11-2017, 15:21   #6
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Re: Another plotter assisted grounding?

Quote:
Originally Posted by zboss View Post
Hereís the rub... if you lay down a rhum line between two points and the line goes over an obstacle the chart plotter should really inform you of it - regardless of the zoom level. You should be able to set the width of the rhum line so it can pick up anything within a specified distance off the rhum line as well. You canít do anything about things that arenít plotted at all but it would at least take care of the silliness that zooming is.

Sounds possible with vector charts. Not sure there's a way to make it work with raster...

-Chris
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Old 13-11-2017, 15:34   #7
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Re: Another plotter assisted grounding?

Quote:
Originally Posted by zboss View Post
Hereís the rub... if you lay down a rhum line between two points and the line goes over an obstacle the chart plotter should really inform you of it - regardless of the zoom level. You should be able to set the width of the rhum line so it can pick up anything within a specified distance off the rhum line as well. You canít do anything about things that arenít plotted at all but it would at least take care of the silliness that zooming is.
Good point. I don't have a lot of sea miles to get into an educated discussion here but the guys I've been with that do have those sea miles keep zooming in for details even with a course being set.

I don't remember who wrote it but the comment was to the effect that 'good navigators are always a little bit paranoid'. :-)
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Old 13-11-2017, 16:34   #8
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Re: Another plotter assisted grounding?

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Sounds possible with vector charts. Not sure there's a way to make it work with raster...



-Chris


Agreed, raster charts are fairly useless. The only reason they are still around is that they are human readable, which is worth zero to a computer.
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Old 13-11-2017, 17:31   #9
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Re: Another plotter assisted grounding?

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Agreed, raster charts are fairly useless. The only reason they are still around is that they are human readable, which is worth zero to a computer.
Because for damn sure we do not what any humans reading our charts. It's the humans that are worthless. They should stay on land and let their chartplotters send them video they can post on youtube.
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Old 13-11-2017, 17:33   #10
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Re: Another plotter assisted grounding?

When I am navigating people have said I worry too much. I explain the things I worry about I take care of so they never happen

The real things to worry about are the things I don't know enough to worry about...
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Old 13-11-2017, 17:35   #11
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Re: Another plotter assisted grounding?

My paper charts and a sharp pencil makes the whole problem go away.

I know for SURE I am never going to trust a computer to route me across the ocean. I know I have to review the whole route MYSELF. What makes this so hard that you think a computer has to do it?
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Old 14-11-2017, 09:36   #12
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Re: Another plotter assisted grounding?

Our Garmin worked fine a few years ago going into San Jose del Cabo. But when we left a week later it showed a solid wall between us and the open ocean. I trusted my eyes at that point, and my razor sharp memory, and we sailed right through the invisible force field. I always assume my chartplotter is going to quit on me, so I keep a pad by it and write down my coordinates several times a day. And when we near land I scour paper charts for more information and or hidden dangers.
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Old 14-11-2017, 09:40   #13
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Re: Another plotter assisted grounding?

With references to relying on charts, paper, raster, or vector, I got a lesson six months ago about the accuracy of US Coastal Charts in little-used waters. Entering Doboy Sound in Georgia, I found the charted depths to be wrong by at least 7 feet. I came within 3.5 feet of grounding, and it wasn't an isolated shoal - I was seeing 3.5 to 5 under the keel for about a mile. Minimum depth, per the chart was 13 feet at low tide, but at a little more than half tide, I was seeing 3.5 feet under the keel, so 9 feet. Since tides in that area are 7 feet and more, at low tide I would have grounded. I later check my paper chart to see if there was any discrepancy with the chartplotter, but two different chart software and the paper chart matched exactly, and all three had been updated within two months of the trip.

With the budget cuts to NOAA, I don't expect the situation to improve in the US any time soon, so I stick to channels I know are maintained or ones where I know they get a lot of traffic and I have local information. Maybe the captain of the patrol boat was following the chart, doing everything right, and the chart data was out-dated.
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Old 14-11-2017, 09:44   #14
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Re: Another plotter assisted grounding?

Quote:
Originally Posted by zboss View Post
Hereís the rub... if you lay down a rhum line between two points and the line goes over an obstacle the chart plotter should really inform you of it - regardless of the zoom level. You should be able to set the width of the rhum line so it can pick up anything within a specified distance off the rhum line as well. You canít do anything about things that arenít plotted at all but it would at least take care of the silliness that zooming is.
That's only going to work if you are in a powerboat that can drive in a straight line or you are sailing downwind with a powered autopilot in charge. Vane gear and upwind sailing means you are not going to be closely following that line.
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Old 14-11-2017, 09:50   #15
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Re: Another plotter assisted grounding?

I plot with paper charts first. I then plot (digitally transcribe) the course into th e GPS manually. I zoom in and out throughout the entire course on the GPS. I give everything wide berth.

I was criticized (jokingly) by a buddy boat I was cruising with this summer. I went 1-2 miles out of my way, he cut the corner. I pointed out all the rocks he passed over. He assured me that they were fine, and they he'd done it many times. I then pointed out the rock that was awash. He said "Well you need to stay away from that one". I then showed him that the one that was awash (the one which was to be avoided) was marked identically to the 20 he passed over.

The only difference on the chart, was there was a marker beside the one that was awash.
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