What really means "dangerous rocks?"

[Sailorbob8599]

Which reminds me of this:

ACTUAL transcript of a US naval ship with Canadian authorities off the coast of Newfoundland in October, 1995. This radio conversation was released by the Chief of Naval Operations on 10-10-95.

Americans: "Please divert your course 15 degrees to the North to avoid a collision."

Canadians: "Recommend you divert YOUR course 15 degrees to the South to avoid a collision."

Americans: "This is the captain of a US Navy ship. I say again, divert YOUR course."

Canadians: "No, I say again, you divert YOUR course."

Americans: "THIS IS THE AIRCRAFT CARRIER USS ABRAHAM LINCOLN, THE SECOND LARGEST SHIP IN THE UNITED STATES' ATLANTIC FLEET. WE ARE ACCOMPANIED BY THREE DESTROYERS, THREE CRUISERS AND NUMEROUS SUPPORT VESSELS. I DEMAND THAT YOU CHANGE YOUR COURSE 15 DEGREES NORTH. THAT'S ONE-FIVE DEGREES NORTH, OR COUNTER MEASURES WILL BE UNDERTAKEN TO ENSURE THE SAFETY OF THIS SHIP."

Canadians: "This is a lighthouse. Your call."

[deblen]

Some examples of rocks that are dangerous 1/2 the time. Be particularily careful of anything called a halftide rock

[reed1v]

Originally Posted by Chas.7

Hello,
The best way to stay out of trouble is to avoid it. Any charts without controlling depth notes and few depth numbers or depth contour lines should be suspect. I sailed the Yellow Sea, when ever I have doubts about an area I would talk to a local fisherman.
Good luck

Did not work for us. We went on a reef by following a local fisherman's advice in the south china sea. Different drafts, different ideas as to what is dangerous.

BTW what were you doing that far north? Most cruisers try to avoid that area given the number of collisions, boardings, and seizures that have occurred over the past 40 years in that area.

[El Pinguino]

I don't know what charting system you are using there.

However that info box is dodgy.

If that is a chart of LIS I would suggest that those rocks are well charted.

How much water is over them? Not very much when they use that symbol...
'Unknown depth' together with the '+' symbol with a dot in each quadrant means 'not enough water to float the survey boat'

Would I avoid them? Yes.

[TurninTurtle]

Originally Posted by Sailorbob8599

Which reminds me of this:

ACTUAL transcript of a US naval ship with Canadian authorities off the coast of Newfoundland in October, 1995. This radio conversation was released by the Chief of Naval Operations on 10-10-95.

Americans: "Please divert your course 15 degrees to the North to avoid a collision."

Canadians: "Recommend you divert YOUR course 15 degrees to the South to avoid a collision."

Americans: "This is the captain of a US Navy ship. I say again, divert YOUR course."

Canadians: "No, I say again, you divert YOUR course."

Americans: "THIS IS THE AIRCRAFT CARRIER USS ABRAHAM LINCOLN, THE SECOND LARGEST SHIP IN THE UNITED STATES' ATLANTIC FLEET. WE ARE ACCOMPANIED BY THREE DESTROYERS, THREE CRUISERS AND NUMEROUS SUPPORT VESSELS. I DEMAND THAT YOU CHANGE YOUR COURSE 15 DEGREES NORTH. THAT'S ONE-FIVE DEGREES NORTH, OR COUNTER MEASURES WILL BE UNDERTAKEN TO ENSURE THE SAFETY OF THIS SHIP."

Canadians: "This is a lighthouse. Your call."

That one is a joke... and has nothing to do with reality.

Sometimes its a cruiser... sometimes a battleship.

Sometimes its the US Navy and Canadian Lighthouse, sometimes its British and the Statue of Liberty (which is a lighthouse)
(I've seen it being posted about 15 different countries' warships)

Happy youtubing... there's at least 20 versions there.

[Cadence]

Originally Posted by TurninTurtle

That one is a joke... and has nothing to do with reality.

Sometimes its a cruiser... sometimes a battleship.

Sometimes its the US Navy and Canadian Lighthouse, sometimes its British and the Statue of Liberty (which is a lighthouse)
(I've seen it being posted about 15 different countries' warships)

Happy youtubing... there's at least 20 versions there.

People with nothing else to do. The first few posts answer the Op question.
Captain Cook did charts in some places with a lead line and those places still exist.

JMHO

[Rustic Charm]

Rocks don't kill people, people kill people

[Captain Bill]

Originally Posted by clifflyon

Does anyone know the origins of this data? What are the criteria for mapping? Why so vague and erroneous?

Who is the audience?

Fisherman? Commercial?

I'm tired of steering around them or at least feeling guilty when I don't. 😅

I don't see any indication of what brand of chart you are using. The screen shot provided looks like the yellow banks area of the Bahamas. Official Bahamas charts are notoriously bad/incomplete. Most commercially available charts are compiled from a combination of sources, many of which are not official. These may include data from the "Exlplorer" charts, official government charts and georeferenced data provided by users such as Navionics community supplied edits. Such data may have questionable accuracy so the obstructions are noted to provide information but the information may not have been verified.

[Sailorbob8599]

Originally Posted by TurninTurtle

That one is a joke... and has nothing to do with reality.

Sometimes its a cruiser... sometimes a battleship.

Sometimes its the US Navy and Canadian Lighthouse, sometimes its British and the Statue of Liberty (which is a lighthouse)
(I've seen it being posted about 15 different countries' warships)

Happy youtubing... there's at least 20 versions there.

Lighten up friend, of course it's a joke! (actually an urban legend). Do we have to be serious all the time?

[Sailorbob8599]

Originally Posted by Cadence

People with nothing else to do. The first few posts answer the Op question.
Captain Cook did charts in some places with a lead line and those places still exist.

JMHO

Oh dear Cadence, sorry for being so flippant, did someone piss in your cornflakes?

[TurninTurtle]

hitting rocks or collisions at sea are not funny.

[bigpuff]

I was once coming down the Malacca straits in a 70 ft. yacht with pre-war charts (foto copied) I new that some of the rocks had since been blown up and cleared but were ever it stated dangerous rocks i kept WELL clear,no second chances at sea.

[Cadence]

Originally Posted by Sailorbob8599

Oh dear Cadence, sorry for being so flippant, did someone piss in your cornflakes?

I think my cornflakes are fine. Maybe I didn't word it right. The point was meant to point out some places haven't been charted since then.

[boatman61]

Originally Posted by TurninTurtle

hitting rocks or collisions at sea are not funny.

It is after the event if one has a sense of humour..

[Lepke]

Surveys are for safe navigation, not for enabling sailing thru reefs, etc. They spent their time getting the bulk of the waters surveyed. Often a cable was towed between 2 boats at a set depth. Many charts contain areas surveyed before GPS. Some before accurate time pieces.
Some chart additions were from ships unsure of their position. Some from ships that didn't know their position was inaccurate. Years ago, I'd been in places where the charts/maps were known to be 3 to 5 miles off.

While the lighthouse aircraft carrier stories are humorous, they have no basis in reality. They do not reflect what happens on a ships bridge nor how communications occur. In modern times, I know of no manned lighthouses.