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Old 20-01-2013, 09:26   #46
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Re: U.S. Navy ship goes aground due to bad charts

Those last two photos show that the sea action has turned GUARDIAN beam to the reef....not good for the bottom and by now, props, shafts and rudders are toast. It does, however present a better aspect for a pull off the reef. Hope tthey get a line on her soon, before the seas start to break her up.
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Old 20-01-2013, 09:27   #47
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Re: U.S. Navy ship goes aground due to bad charts

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Originally Posted by Snore View Post
Best argument EVER for paper charts. Electronic charts never seem to have all the notations. Or they are unreadable on a 6-7" screen

Bill
A lot of paper charts these days are POD - print on demand from digital files. Chances are if the source data is inaccurate, the paper chart would also have the same error as the DNC.

Even if this ship had forward-looking sonar that was manned, an obliquely-angled upslope, particularly a sand-covered coral reef might not give a decent return until it's too late. If the chart really did have the reef 8NM out of position, I would think it possible the CO and OOW might be exonerated.
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Old 20-01-2013, 09:37   #48
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Re: U.S. Navy ship goes aground due to bad charts

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If the "digital" data on this reef is incorrect, you can bet the "paper" data is also wrong.

This might be the result of a button-pusher accidently using US feet coordinates instead of INTERNATIONAL feet, or using a wrong datum when trying to mesh different sets of data together.

In any case, I'm willing to bet if the digital data is wrong, that the paper data is also wrong.
For unknown reasons there are many well-documented differences between NOAA ENC and raster charts. One would think they come from the same data, but they are frequently different. Panbo has been discussing this for years. Differences too between various private company electronic charts too.
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Old 20-01-2013, 09:47   #49
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Re: U.S. Navy ship goes aground due to bad charts

Looking at the charts and dive map in the link that CAGNEY (#41) posted, it is obvious that there is a flashing light at the South end of Black Rock, and a Ranger station at the south end of the North Reef. Both should have been easy to spot at night. Why it was missed, will be interesting to find out.
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Old 20-01-2013, 09:49   #50
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Re: U.S. Navy ship goes aground due to bad charts

There are TWO types of electronic charts and while they are both often referred to as "electronic charts" they are NOT THE SAME.

These two are:

1. raster charts; and
2. vector charts.

NOAA refers to these as "RNCs" and "ENCs".

Raster charts are basically a picture...a photograph...of the paper charts. They are EXACT representations of the underlying paper charts.

Vector charts are much smaller (which is why virtually all "chartplotters" use them) and ARE NOT exact reproductions of the paper charts.

NOAA has two separate tracks for production of these charts, and tries very hard to make them comparable. Unfortunately, this isn't always the case, and while vector charts have some advantages (size, "layers", easier updating, etc.) they also suffer for both errors of commission and errors of omission.

Paper charts, and the electronic representations thereof, still in 2012 underlie the production of ALL NOAA charts.

Vector charts are produced by several other government and private agencies, sometimes (mostly) by hand "digitizing". Errors creep in, for lots of reasons. Much of the detail of land masses is omitted.

Which is more accurate? Arguments can be made on both sides, but in my experience the latest RASTER chart (exact electronic reproduction of the underlying paper chart) are more accurate and more useful. That's the only kind I use ... on a laptop computer ... and the only kind I really trust.
Up to a point :-)

FWIW,

Bill
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Old 20-01-2013, 10:04   #51
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Re: U.S. Navy ship goes aground due to bad charts

I'll bet Google Earth shows that reef in exactly the right spot. The chartmakers need to be 'modernized' with a cattle prod.
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Old 20-01-2013, 10:06   #52
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Re: U.S. Navy ship goes aground due to bad charts

If they had used Google Earth they would have seen it long before they got there.

It's kind of out in the middle of nowhere unless you actually look at an underwater chart like this. I remember coming pretty closes to some surf action over by Guam once and looked over to see a rock sticking up out of no where.
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Old 20-01-2013, 10:11   #53
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Re: U.S. Navy ship goes aground due to bad charts

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Originally Posted by captain465 View Post
Those last two photos show that the sea action has turned GUARDIAN beam to the reef....not good for the bottom and by now, props, shafts and rudders are toast. It does, however present a better aspect for a pull off the reef. Hope they get a line on her soon, before the seas start to break her up.
I find it astonishing that the CO of that ship would not have gotten stern anchors out to have prevented this. That is very poor ship handling, at the least, in my view. Moreover, I cannot fathom how you could think recovering/refloating the ship would be easier from such an attitude. Damages to the bow section can be isolated. There is/would be no way to isolate damages to the entire length of the hull. IMHO someone's, perhaps several someone's, career(s) should be over.
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Old 20-01-2013, 10:14   #54
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Re: U.S. Navy ship goes aground due to bad charts

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Frankly, I would have thought that a minesweeper, of all vessels, would have some sort of forward looking sonar that would have alerted them in time.
So let's be honest - how many of us set depth alarms?

That's what woukd have saved these guys.

It's a certain amount of work, but if you expect 30 meters plus over the whole passage, an alarm set at 3 meters under the keel can be very informative about our assumptions
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Old 20-01-2013, 10:25   #55
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Re: U.S. Navy ship goes aground due to bad charts

If you look at the charts, the reefs have an almost vertacle wall, depths are beeetween 400 and 1000 METERS, depending on where the Gardian went on. I don't think that anyone coud have deployed a stern anchor after the vessel went aground, nor do I think there are stern anchors in place on those mine warfare vessels. (They did not when I was in USN on Minesweeper repair ship.)
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Old 20-01-2013, 10:35   #56
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Re: U.S. Navy ship goes aground due to bad charts

No electronics can totally replace that good old watch!! Does anyone know at what local time she went aground' I'll bet it was between 0100 and 0430---nothing like an able sailor watching the bow, radar and the forward underwater depth scanner that is probably on this type of vessel. Thank goodness no one was serioulsy injured!
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Old 20-01-2013, 10:37   #57
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Re: U.S. Navy ship goes aground due to bad charts

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So let's be honest - how many of us set depth alarms?

That's what would have saved these guys.

It's a certain amount of work, but if you expect 30 meters plus over the whole passage, an alarm set at 3 meters under the keel can be very informative about our assumptions
Normally there is a Radarman on watch at all times underway. It may have come up so fast that there wasn't enough time to react. God knows how hard I've run aground when I thought I was in the deep, to find a rock on the charts after already hitting it.
That's what happens when one's lolly gagging admiring the sights. In their case a nice night cruise in the tropics.
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Old 20-01-2013, 11:09   #58
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Re: U.S. Navy ship goes aground due to bad charts

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Originally Posted by Dockhead View Post
So let's be honest - how many of us set depth alarms?

That's what woukd have saved these guys.

It's a certain amount of work, but if you expect 30 meters plus over the whole passage, an alarm set at 3 meters under the keel can be very informative about our assumptions
Mine is almost always set, but at a low enough depth to not be alarming all the time. 10 ft etc.
It's amazing if you look at the picture, that someone on watch didnt just see the breakers around the shallow spot. What the heck were these guys doing????
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Old 20-01-2013, 11:15   #59
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Re: U.S. Navy ship goes aground due to bad charts

Have you ever tried to stop a ship that size at cruising speed. Even if the sonar alarm went off it still would have hit the reef.
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Old 20-01-2013, 11:17   #60
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Re: U.S. Navy ship goes aground due to bad charts

maybe not if forward scanning, or maybe they would have been able to slow down enough for a minimal grounding they could have backed off of... hard to say I guess.
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