• Quick note - the problem with Youtube videos not embedding on the forum appears to have been fixed, thanks to ZiprHead. If you do still see problems let me know.

Cont: The Sinking of MS Estonia: Case Re-opened Part IV

Status
Not open for further replies.
US Navy, Handbook of Damage Control covers buoyancy and stability in the chapters below.

Chapter III, Fundamentals of Buoyancy and Transverse Stability
Chapter IV, Stability Characteristics
Chapter V, The Inclining Experiment
Chapter VI, Weight Shifts and Transverse Stability
Chapter VII, Weight Changes and Transverse Stability
Chapter VIII, The Effects of Loose Water
Chapter IX, Stability Data for Standard Conditions of Loading
Chapter X, Longitudinal Stability and the Effects of Trim
Chapter XI, Curves of Form
Chapter XII, The General Stability Diagram
Chapter XIII, Impaired Stability
Chapter XIV, List

Link to online version of the manual
https://maritime.org/doc/dc/
 
whoanellie said:
I'm starting to wonder if Vixen realizes there are 360 degrees on a circle.
Click to expand...

Vixen said:
A boat is only a half circle in shape, thus if port is at 45° and starboard at 135°, it is indeed standing perpendicular to the deck and now parallel with the water's surface when turned 90°. However, it only takes a list of just 45° for the side of the boat to be irrevocably in a state of impending capsize. At 90° this has surely already happened. And if it has turned more than 90° then it means the rotational force has reversed and it would have continued turning upside down, were it not for the sand bank, where it came to rest.

The guy in the video uses 0° for the centre of gravity thus making it clear what the angle of list is and of course, it depends on the shape of the hull as to what point it tips over. At at an angle of 70° list (or at 160° to the surface of the water) it is likely already at negative gravity and capsize imminent. By 90° it is certainly not floating om its side, it is in the final throes of turtling. (Ceteris paribus)
Click to expand...

Well I was right. :D Vixen doesn't even get that there are 360 degrees in a circle. Port and starboard are 180 degrees apart. 135 - 45 = 90, not 180.

Of course, the center of gravity is a point in 3-D space not an angle.

What the hell is negative gravity?

I guess this is what 5 years of physics education gets you.

Never mind, whatever Vixen wrote must be true because it's all "Ceteris paribus".
 
Last edited:
Vixen said:
Not in a car ro-ro ferry with free surface flooding, it is not.

As most ship sinkings are to do with machinery problems (fire, pipes, slow flooding) or collisions then your last para might be true but doesn't hold true for the type of vessel MS Jan Heweliusz, Estonia or The Herald of Free Enterprise was.

In fact, you are the outlier as it is generally accepted that The Herald of Free Enterprise would have turtled but for the sand bar. What stopped Estonia from turtling?
Click to expand...

Why do persist in using this odd term? A scientist (such as yourself :p) should be stickler for accuracy in their communications. The correct term you should be using is *capsize*. As has previously been pointed out turtles have no propensity for turning upside down.
 
Steve said:
Why do persist in using this odd term? A scientist (such as yourself :p) should be stickler for accuracy in their communications. The correct term you should be using is *capsize*. As has previously been pointed out turtles have no propensity for turning upside down.
Click to expand...

One of the origins for the term I am familiar with is that the hull of a ship that is floating upside down resembles a turtles shell.
 
Steve said:
Why do persist in using this odd term? A scientist (such as yourself :p) should be stickler for accuracy in their communications. The correct term you should be using is *capsize*. As has previously been pointed out turtles have no propensity for turning upside down.
Click to expand...

As I understand it. a ship that has capsized can be on its side or hull up. Turtle refers only to the latter.
 
Last edited:
Vixen said:
AFAIA David Irving has a far-right neo-nazi political agenda and he and his publications are rightly shunned and excoriated.
Click to expand...


So why shouldn't Björkman and his outrageous, ridiculous, and highly offensive claims about the atomic bombing of Japan be shunned and excoriated?

Vixen said:
Someone interested in 9/11, JFK, Big Foot, is hardly a criminal.
Click to expand...


Who said anything about criminality?

Vixen said:
Some people enjoy discussing ideas, others not. If you come from an intellectual background, it is really not a big deal if someone is curious about something or other.
Click to expand...


Again, Björkman's claims are outrageous, ridiculous, and highly offensive. Kindly explain how his promotion of them demonstrates any level of curiosity.

Vixen said:
Can we now get back to the topic and not a discussion of personalities?
Click to expand...


As Jay has pointed out, you are attempting to qualify Björkman as an expert in order to bolster your conspiracy narrative. Calling attention to claims he has made that suggest he is both incompetent and not in touch with reality is perfectly proper.
 
Captain_Swoop said:
One of the origins for the term I am familiar with is that the hull of a ship that is floating upside down resembles a turtles shell.
Click to expand...

Still, not the scientifically accurate term that our "scientist" correspondent should be using.

Although you make a valid point that things that resemble (in her own mind) other things are crucial to many of Vixen's arguments
 
Jack by the hedge said:
Did the relatively small degree of list at departure actually require people to use mountaineering equipment to climb up the decks? So confusing.
Click to expand...

No, but the fact that the ballast tanks were full to try and correct the list caused by the bad cargo loading contributed to the sinking.
 
Vixen said:
A boat is only a half circle in shape, thus if port is at 45° and starboard at 135°, it is indeed standing perpendicular to the deck and now parallel with the water's surface when turned 90°. However, it only takes a list of just 45° for the side of the boat to be irrevocably in a state of impending capsize. At 90° this has surely already happened. And if it has turned more than 90° then it means the rotational force has reversed and it would have continued turning upside down, were it not for the sand bank, where it came to rest.

The guy in the video uses 0° for the centre of gravity thus making it clear what the angle of list is and of course, it depends on the shape of the hull as to what point it tips over. At at an angle of 70° list (or at 160° to the surface of the water) it is likely already at negative gravity and capsize imminent. By 90° it is certainly not floating om its side, it is in the final throes of turtling. (Ceteris paribus)
Click to expand...

What is this? I don't even.
 
Vixen said:
Imagine a flat board of wood say, ten feet long and five feet wide, one foot depth, floating on a calm stretch of water. You are standing at its centre of gravity and are perfectly buoyant. The force of gravity pulling downwards and the centre of buoyancy pushing upwards means you are superbly balanced. You then step to your right a couple of feet. You are now not at the centre of gravity. Being flat wood, there is no righting mechanism as one would have on a boat. The board tips over toppling you out in the process.

Question: Does the flat board of wood float on its twelve-inch side even for a minute?
Click to expand...

I wondered about this and about what would really happen. The answer, of course, is "it depends". :)

But lets say Vixen makes me a 5 x 10 x 1 foot raft of solid Baltic pine (around 520kg/m³, fact fans) and floats it in the brackish Baltic sea. I weight 100kg in my boots (yeah, the TV and beer diet's not working) and my back-of-an-envelope calculation suggests I can balance right at the farthest edge of her raft without getting my boots wet. Ceteris paribus, of course.

Now I just used my decades-ago school physics to try to work out what the restoring moment would be if the raft tipped until its edge touched the water line then thought where I'd have to put a 100kg mass to keep it there and it seemed to be beyond the edge. I may well have messed up a calculation, but it amused me.
 
Vixen said:
Sheen clearly states the vessel had turned over more than 90°.
Click to expand...

And he specifically says that what stopped it from turning over more was not that it hit bottom. You seem to have this extremely naive belief that once a ship has gone past 90°, and there's no sandbar to stop it, it will necessarily continue on to roll to 180°. There's simply no physical reason to believe that.
 
Vixen said:
Capsize = turn over.
Click to expand...

No. Turtle = turn over. Capsize = a non-transient roll to the extent that the ship can no longer be navigated. Naval architects, like most experts, have a precise vocabulary despite how lay people may use the same words.

A ship doesn't float on its side.
Click to expand...

It surely can, despite your uninformed belief to the contrary.

Imagine a flat board of wood...
Click to expand...

...which is nothing like a ship. Don't try to reason by irrelevant analogy. Just do the math.
 
Status
Not open for further replies.

Back
Top Bottom