The Sinking of MS Estonia: Case Re-opened Part II

[Vixen]

All you need to do to sink a boat is let water in. You don't need to overload it. In a dinghy the easiest way is to tip it over.

I remember when I learned to sail many decades ago with the Sea Cadets, it was quite difficult to make a dinghy turn right over to do recovery drill on a capsized boat.
It was easy to get it on it's side but more difficult to force it further over.

Exactly so an overturned boat doesn't sink straight to the bottom by your own account.

 

[Jack by the hedge]

Because if the Estonia only capsized because of water ingress into the car deck, the list of 40° would have caused it to capsize belly up, not immediately sink, although it would have sunk eventually as the water filled the air spaces of the superstructure. The windows in a ship are not like house or shop windows they are tough reinforced glass designed not to break even under extreme pressure.



Frogmen had to cut away the glass on the bridge with oxy-acetyline in order to enter.



So much for the JAIC assumption of the windows having broken when in contact with water pressure.

That's a lot of words to say *if* the seawater only flooded the car deck and no further the ship would not have sunk.

I presume indestructible windows cut with oxy-acetylene is bait inviting further derails.

 

[Jack by the hedge]

Kurm Sept 2021 found the passenger car deck doors intact and shut.

On which side of the ship?

 

[Andy_Ross]

The maximum capacity of water on the car deck of the Estonia is 18,000 tonnes, thus it is balanced out by the hull.

How does that work?
What is 'balanced out?
We went through this in great detail earlier in the thread.
Remember 'free surface effect'?

half a mater of water on the car deck would be 2000 tons.
When the ship rolled that water flowed to the lower side of the deck. That was enough to push it beyond it's roll recovery point.
Once openings were submerged water would start to flood the lower decks.

 

[Vixen]

Actually, that photo of a rowing eight sinking is an excellent example to take.

It's a great example for this reason: these sorts of rowing boats don't typically sink because they collide with something, or because they develop leaks. They sink because they have very little free board (in order to facilitate fast and efficient rowing strokes) - which means it's relatively easy for water from the lake/river to splash above that free board and into the boat. The boat is buoyant when its cargo is merely the rowers and the cox. But if/when more water gets over the side and into the boat than can be auto-bilged out, there comes a point when the additional mass of this water pushes the boat past its buoyancy limit. And it starts to sink.

Furthermore, there's ample empirical evidence (not least from the televised annual Boat Race in the UK) that when these sorts of rowing boats start to sink in this way, they simply sink straight downwards, without capsizing. As your photo elegantly shows.....

Oh dear. The Estonia turned on its side at 90° and sank right down within 35 minutes. The MS Jan Heweliusz turned on its side due to water ingress onto the car deck and all of its concrete botched repair jobs notwithstanding, it floated belly up for a further five days.

 

[Andy_Ross]

Because if the Estonia only capsized because of water ingress into the car deck, the list of 40° would have caused it to capsize belly up, not immediately sink, although it would have sunk eventually as the water filled the air spaces of the superstructure. The windows in a ship are not like house or shop windows they are tough reinforced glass designed not to break even under extreme pressure.

Frogmen had to cut away the glass on the bridge with oxy-acetyline in order to enter.

So much for the JAIC assumption of the windows having broken when in contact with water pressure.

WHy would it have floated 'belly up'?
You srtill haven't shown any support for this?

By far the huge majority of ships that sink do not turn 'belly up'

Windows on the ship would certainly break due to the imbalance of pressure What is your evidence that they wouldn't?

 

[Vixen]

Yes. And when it reaches that 90° inclination, it usually sinks in that inclination. It doesn't continue rolling until it's completely upside down, as Vixen would (for some reason) like to believe.

Good Grief O'Riley. Still on the Herald of Free Enterprise lying on a shallow bank are we?

 

[Vixen]

On a kind-of-related topic, I remember an episode of Mythbusters (in its original incarnation) where they were testing the effects of inflation pressure on the throwing/placekicking distances of a (American) football. They tried the test using either regular air or helium to inflate the footballs, at varying inflation pressures.

Before each test, they weighed the football. And it temporarily bamboozled even the great Adam and Jamie when the football inflated with helium to (say) 16psi was heavier than the same football inflated with helium to (say) 11psi. Instinctively, one would be tempted to think that "more helium" equals "lighter". But, of course, if that "more helium" is contained/constrained within the same volume (here, the internal volume of the football), it is indeed heavier.


(Not to mention the fact that more helium - whatever volume it's contained within - always has a greater mass than less helium. It's just that one would have to assess the helium in a vacuum to make that determination, owing to the fundamental difficulty of "weighing" helium when it's surrounded by air)

That's telling that Archimedes bloke.

 

[Vixen]

I suppose so. I’m still not convinced of the relevance of bulkheads to water flooding the car deck of a ferry, in any case.

Er, they are in the hull. See the green bits on the diagram.

 

[Vixen]

Well, they're not relevant, are they?

I suspect this may have been intended as a set-up for Vixen to revisit some of her earlier theories about passanger cabins being watertight, and 'therefore there must have been a breach in the starboard side of the hull'. There was something about swimming pools in there, too. Maybe l'm just a cynic.

I hope we get the one with the mini-sub, that was a favourite of mine.

The only unsealed areas of the hull were the engine room, the swimming pool and sauna and public toilets IIRC.

 

[Andy_Ross]

Er, the MS Jan Heweliusz a good comparator to the Estonia and in a terrible unseaworthy state that I believe the owners were charged with manslaughter. Yet this ramshackle ferry stayed afloat turtled for five days, nonetheless.

Jan Heweliusz did not lose it's bow. It was already an unstable ship. It was already known to have ballast problems and the stability was further reduced following repairs to the upper deck which involved pouring around 100 tons of concrete to level it out.
It also sailed in hurricane force winds and far worse conditions than the Estonia.


Have you been reading.

Björkman, Anders,(2007). Estonia revisited +Learning from the often forgotten Jan Heweliusz disaster
http://estonia.kajen.com/Naval_Architect_Jan_07.pdf

 

[Vixen]

No. I'd rather not argue about predictions based on "principles" when I have everything I need to try it out for myself.

Awaiting your instructions for how to introduce the water in an appropriately unbalanced way, for your clearly stated prediction of the results based on the principles you describe, and of course your wager.

A boat is designed to float. Why would anyone deliberately try to make it sink. It doesn't disprove anything, does it? You can make it sink by simply drilling a hole in the hull. Why waste time filling it with water?

 

[Jack by the hedge]

That's telling that Archimedes bloke.

Archimedes is not on your team here. His principle is not "all foundering ships roll over and float unless sabotaged".

 

[Jack by the hedge]

The only unsealed areas of the hull were the engine room, the swimming pool and sauna and public toilets IIRC.

How did any passengers escape then?

 

[Vixen]

We're talking about two things. You've conflated them incorrectly because you're letting Anders Björkmann teach you his special brand of physics. Capsizing has to do with the balance of roll moments and righting moments and has nothing to do with a change in buoyancy. Sinking has to do with a change in buoyancy, which has nothing to do with roll. In your haste to appear smart, you've cited factors for one as if they were factors for the other, and are frantically trying to suggest that your critics don't understand "simple" physics. And now you're waffling your way out of a practical experiment to demonstrate that "simple physics" doesn't do what you say it does.



Displaced with respect to what? What are the forces involved? Upon what centers do they act? What physical phenomena define these centers? In what directions must each force act? What are the force vectors involved, and how do they sum? Draw us a diagram that shows that a mere change in the magnitude of the buoyancy vector will also necessarily change the center where it acts and thus create a roll moment that inevitably capsizes the ship.



No. When a vessel lists at 90° it lists at 90°. When a vessel lists at 180° it will have capsized belly-up because that's just a different way of saying that's what its roll angle is. This is a function of the vector sum of forces and the dynamics of it are driven by factors that are only partly related to the magnitudes of these vectors. You present a source that deals only in the magnitude of vectors (in fact eliminating the vector reality altogether) and cite it as proof that the directions of these vectors and where they act upon the structure of the ship makes capsizing inevitable.

In practical shipbuilding, once a vessel has rolled to particularly degree and after the righting moment is no longer strong enough to restore trim, openings in the vessel become vulnerable to shipping water into the hull that a were intended to remain above water. The notion that any ship whose "hull is not breached" will float upside down for hours in any roll attitude is naive.



A superstructure changes the vector sum, to be sure. But in ways your model of the dynamics doesn't properly consider. Draw us vector diagrams of a ships with and without a superstructure and show how the sums change as buoyancy increases or decreases.



Ah, we're to the, "You may be an expert, but I say you're lying," stage of the conspiracy-theorist's pattern argument.

I don't need to draw you a diagram, as it is all readily available on the internet.

The understanding of a surface ship’s stability can be divided into two parts. First, Intact Stability. This field of study deals with the stability of a surface ship when the intactness of its hull is maintained, and no compartment or watertight tank is damaged or freely flooded by seawater.

Secondly, Damaged Stability. The study of damaged stability of a surface ship includes the identification of compartments or tanks that are subjected to damage and flooded by seawater, followed by a prediction of resulting trim and draft conditions.

Marine Insight

 

[Mojo]

Er, they are in the hull. See the green bits on the diagram.

I’m still not convinced of the relevance of bulkheads to water flooding the car deck of a ferry, in any case.

 

[Andy_Ross]

Kurm Sept 2021 found the passenger car deck doors intact and shut.

Two doors out of how many openings to the lower decks?

You do realise that there are a number of passenger doors from the car deck as well as crew access, ventilators and various air intakes and exhausts.
Once the ship had a list other openings would be below the surface.

 

[Vixen]

I'm sure there are several other routes water could have taken off the car deck and deeper into the ship but if, as seems very likely to me, the only two doors which were accessible for inspection are on the side of the wreck which lies uppermost then they'd be entirely irrelevant to the sinking anyway.

Kurm's September expedition was a preliminary one but now the two intact doors have been discovered it may mean a return visit in Spring to check out the other doors and wndows.

In the case of the investigation of the car deck, Kurm once again pointed out the fact that the two passenger doors in its central section were closed. Kurm explained that the discovery is important because previous simulations have assumed that the doors broke.

"The fact that the two doors are in front and intact does not mean that the other doors are also in front and intact," Kurm said, admitting that they could not get more detailed information with the robot.

Press udpate 12.10.2021

 

[Vixen]

Indeed, I suspect she's pursuing this line of argument because the "principles" she's alluding to are those put forward by Anders Björkmann. She's learned that citing him as an authority will result in derisive laughter from those of us who know him better than she. But she doesn't have the wherewithal to explain and defend those "principles" herself. So all that's left is bluster, which tends to cave in fairly quickly in the face of practical demonstrations.



Four or five tequila shots should do the trick.

So Anders Björkmann is this weird guy who offered people a million dollars if they could prove him wrong...?

Not like anyone else we know of?

 

[Andy_Ross]

Yes, and they could hang on to the keel of the upturned boat and even right it.

Who could Vikings?

How would they do that when the ship would have sunk?

On a dinghy with built in buoyancy it is possible if you have something to use as a lever like the fin keel of a sailing boat otherwise how would you do it?

Even on a sailing boat if it has gone right over you won't get it upright unless you can clear the sheets etc to make sure the sail is free.
Even then it only works for a small dinghy with a small sail otherwise the weight of the wet sail and the drag it causes is too much for just a couple of people to overcome.