Korean Ferry Sinking

[ladajo]

Yes that can happen. But that is a significant turn, and bad load as well as Metacentric issues to being with to pull it off.
This particular design also had fin stabilizers, which could limit that excursion as well.

Not saying it couldn't be, but it would need to be worked at. (Unless it is later shown that the design mods and loading put the Metacentric in extremis.

Interesting thought. Thanks. I know its possible, but I don't normally think that way on ships. All my experience has mostly been with very stable designs (battle damage stability margins are large). I trained and certed for stability management a long time ago, it is becoming unfocused with time and distance.

I will offer though, as I rumage around in old brain stashes while I type this, that fin stabilizers can accentuate a roll under certain conditions and timing of actions.
I used to play with this to some degree for fun, figuring out with real life experiements the PID oscillation points to perform what I called then, "Fin Kicks" in extreme maneuvering. Its all in the wrist ...and clock
Some good fun with that. Old memories...

Thanks for stirring my pot.

[ladajo]

I could get up to >35 degree rolls doing it "right" at flank. It will get your attention on a ship.

Of note, I could also turn a ship at flank with a full rudder and maintain a completely level (<3 degrees roll) deck the entire time. Fun science trick.

[paperburn1]

The captain of the ship, Lee Joon-seok, 69, and other crew members have been arrested on negligence charges. Lee was also charged with undertaking an "excessive change of course without slowing down."

This fits with the pre 1995 design of the ship. He turned too sharp and flooded the well deck(car area) and did not get ballasted in time to save the ship.

[paperburn1]

I could get up to >35 degree rolls doing it "right" at flank. It will get your attention on a ship.

Of note, I could also turn a ship at flank with a full rudder and maintain a completely level (<3 degrees roll) deck the entire time. Fun science trick.

I don't know where the yellow gear went Deck chief, It was here just a minute ago.

[ladajo]

I could get up to >35 degree rolls doing it "right" at flank. It will get your attention on a ship.

Of note, I could also turn a ship at flank with a full rudder and maintain a completely level (<3 degrees roll) deck the entire time. Fun science trick.

I don't know where the yellow gear went Deck chief, It was here just a minute ago.

Thus me figuring out how to do the the level deck flank full rudder turns...

[ladajo]

The captain of the ship, Lee Joon-seok, 69, and other crew members have been arrested on negligence charges. Lee was also charged with undertaking an "excessive change of course without slowing down."

This fits with the pre 1995 design of the ship. He turned too sharp and flooded the well deck(car area) and did not get ballasted in time to save the ship.

I saw somewhere else (news...) that they were saying the turn was not as severe as they had thought once they did data analysis.
That said, it sure does look like an interesting theory. If they heeled enough to ship some water, things could have gone south fast. And as stated, I know that you can "trick" the fin stabilizers to augment your roll vice control it with the right turn/timing sequence.

Hmmm.

We will see soon I think. I am surprised that Main Stream has not yet jumped on the why part yet. They are overdue.

[ladajo]

Kim talked to Park at a Mokpo detention facility. He said she told him she ordered a helmsman to make a 5-degree turn that was part of the ship's normal course, but the steering gear turned too far and the helmsman could not turn it back. Tracking data show that the ship made a 45-degree turn, and that it turned about 180 degrees over about three minutes just before it began to sink April 16.

Prosecutors have said they are trying to determine the disaster's cause by examining the turn and other factors, including wind, currents, freight and modifications made to the ship.

Kim said he suspects a problem in the steering gear was behind the ship's sinking, together with freight that was reportedly secured too loosely. He cited reports that the ship's turn led some freight to shift to one side, making the vessel unbalanced.

Foxnews Update

[hanelyp]

... ordered a helmsman to make a 5-degree turn that was part of the ship's normal course, but the steering gear turned too far and the helmsman could not turn it back. ...

Mechanical failure in the rudder control linkage?

[paperburn1]

Ship was now stated to be overloaded with cargo. All the ducks are falling into a row now.

[ladajo]

Improper stowage and overloading of cargo is suspected as a possible reason the ferry sank. The ferry was carrying an estimated 3,608 tons of cargo, more than three times what it could safely carry.

From Fox today. Given the previous mods shifting the metacenter, and the possibility of a cargo shift. Not looking good from a criminal perspective for those involved.

[ladajo]

Improper stowage and overloading of cargo is suspected as a possible reason the ferry sank. The ferry was carrying an estimated 3,608 tons of cargo, more than three times what it could safely carry.

From Fox today. Given the previous mods shifting the metacenter, and the possibility of a cargo shift. Not looking good from a criminal perspective for those involved.