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Old 16-08-2020, 05:15   #1
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Unsurveyed rock up from Bowen NQ Australia

Zolu Waterways have a rock marked that was run into by someone. I guess it's unconfirmed but take care.
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Old 16-08-2020, 07:15   #2
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Re: Unsurveyed rock up from Bowen NQ Australia

Submarine volcano or possible tectonic shift? Or maybe a container of kitchen implements?
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Old 16-08-2020, 16:31   #3
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Re: Unsurveyed rock up from Bowen NQ Australia

Hey, Dave, any chance of getting a lat/lon for the rock? [It should be a well charted area.] The courses for north and south entry are indicated on the chart.

My CM 93 chart shows Wentworth Rks located on the north side of the north channel @ 20 d 01.36' S/148 d 16.52' E, and a whole bunch of rocks SSW of Stone Island, that if you stayed on the south entry course indicated on the chart, you'd be well S of the rocks. You'd want to watch to see you weren't getting set there, lots of hazards to hit. ...This spoken from the vessel that draws 2.2 m, and likes to go the deeper routes.

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Old 16-08-2020, 19:31   #4
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Re: Unsurveyed rock up from Bowen NQ Australia

Quote:
Originally Posted by JPA Cate View Post
Hey, Dave, any chance of getting a lat/lon for the rock? [It should be a well charted area.] The courses for north and south entry are indicated on the chart.

My CM 93 chart shows Wentworth Rks located on the north side of the north channel @ 20 d 01.36' S/148 d 16.52' E, and a whole bunch of rocks SSW of Stone Island, that if you stayed on the south entry course indicated on the chart, you'd be well S of the rocks. You'd want to watch to see you weren't getting set there, lots of hazards to hit. ...This spoken from the vessel that draws 2.2 m, and likes to go the deeper routes.

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Hi Ann

19°59'41.4"S 148°16'24.2"E

It seems odd to me I'd assume there has been a lot of traffic there over the years, I have nothing in that position and I can't see anything on Google maps either but these are experienced sailors so I'd assume they were quite sure.
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Old 16-08-2020, 19:45   #5
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Re: Unsurveyed rock up from Bowen NQ Australia

That's really close to Wentworth Rocks. I wonder if they struck and by the time they hit the MOB button, they'd floated off a bit?
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Old 16-08-2020, 20:21   #6
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Re: Unsurveyed rock up from Bowen NQ Australia

My charts Aus OESENC 2019 and CM93 2025 both have a submerged wreck at
20d 00.1' S 148d 16.56' E
Wentworth Rocks are a fair bit south of there.
Personally, I have always been much farther off shore in that area

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Old 16-08-2020, 21:24   #7
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Re: Unsurveyed rock up from Bowen NQ Australia

Report it to the RAN Hydrographic Service and you might get naming rights for your effort.
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Old 17-08-2020, 00:03   #8
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Re: Unsurveyed rock up from Bowen NQ Australia

Quote:
Originally Posted by JPA Cate View Post
Hey, Dave, any chance of getting a lat/lon for the rock?
The screen shot show Lat/LON as:
-19.99482785335839 148.2734013073257


I'm afraid that's only to the nearest 1/100th of a nanometer, but it should be close enough.
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Old 17-08-2020, 00:53   #9
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Re: Unsurveyed rock up from Bowen NQ Australia

It was pretty close to tiger country and they were following a navionics auto route.

I have had navionics auto route take me in over the wide bay bar via the fisherman's passage on a vessel that was plugged in as 2.5m draft.

Dont trust auto route.

Pic is the rock marked...............rock.

Also of interest would be vessel type.
Multihull with boards up drawing 2 ft or 60 ft maxi drawing 10ft?
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Old 17-08-2020, 03:22   #10
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Re: Unsurveyed rock up from Bowen NQ Australia

Quote:
Originally Posted by StuM View Post
The screen shot show Lat/LON as:
-19.99482785335839 148.2734013073257


I'm afraid that's only to the nearest 1/100th of a nanometer, but it should be close enough.
Point well made. Let's see ... Bowen (land and the immediate seafloor) is moving about 6 centimetres a year towards the NE. So a survey done in 1994 now has a horizontal inaccuracy of 1,600 mm (1.6 metres).

If an electronic chart is sold today, what's the date of validity of its survey?

Or should navigators just accept that we've no charts accurate to high precision. And navigate according.

Remember, Aus is one of the fastest moving continents. Image below shows the movement, relative to GNSS, of the continent (including the continental shelf, right?) from 1994 to 2020.
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Old 17-08-2020, 03:57   #11
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Re: Unsurveyed rock up from Bowen NQ Australia

That shore line is exposed to the prevailing SE winds and has a lot of variation of depth, not a good place to go anyway.
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Old 17-08-2020, 04:03   #12
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Re: Unsurveyed rock up from Bowen NQ Australia

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Originally Posted by Alan Mighty View Post
Point well made. Let's see ... Bowen (land and the immediate seafloor) is moving about 6 centimetres a year towards the NE. So a survey done in 1994 now has a horizontal inaccuracy of 1,600 mm (1.6 metres).

Which means that location would have been incorrect 5 milliseconds after it was recorded because of plate movement.
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