Costa Concordia, 80 deg list, really scary !!

jannake, but u r the one with the white uniform?

 

I'm afraid your appraoch is no way to design a ship. Adequate beam to give enough initial stability undamaged together with adequate freeboard and most ships of this type will have no problems. That does not go for Ro-Ro ferries however, which need much more careful attention!

 

Do not confuse R, the required subdivision index, with A, the attained subdivision index.

Realisticly speaking, if we assume unlimited damage length, only a ship made out of material lighter that water will ever have an attained index anywhere near 1, and in fact 1 is achievable only if the structure and weights below the margin line are positively buoyant and that supports all structure and weights above the margin line with positive stability (think balsa raft). An attained index of 1.0 means that the ship will float above the margin line with all compartments below the margin line open to the sea. Because A is the sumation of the probabilites of all compartments, to all damage, in all (well 3 actually; summer, lightship, and 60% or the difference) loading conditions; it is obvious that there are some conditions that the ship will not survive, nor is expected to survive, such as damage that exceeds 60m in length. Wether this is better or worse than flat "3 compartment" or "4 compartment", etc stability is dependent on actual arrangements and assumed damage length and location.

For a ship built prior to MSC 216, R should have been :R = 1-(1000/(4Ls+N+1500)); where Ls is the subdivision length in meters, and N = boat places+2*excess personnel. So a minimum R would be 0.33 and a maximum would be something just less than 1.0, but never 1.0 or over. Ships built to the current requirement R= 1-(5000/(Ls+2.5N+15225)) So again the minimum R would be 0.32 and the maximum just less than 1.0. What the new rules do however is put more emphasis on people and less on subdivision length.

Is it reasonable to expect the ship to survive any damage to any set of compartments? Must the ship survive a meteor strike, or any other probablisticly small but real calamity that will leave personnel injured/dead but the ship afloat? (Such as the Kaiyo Maru No. 5 loss in 1952) And notice this does not touch on the other mass of SOLAS requirements, which concern the safety of the personnel onboard when the ship is damaged.

 

Deterministic rules do not assume any damage length - they simply require the ship designer to demonstrate that each transverse compartment of his design will fit within the permissible length (which is the floodable length of the vessel at any point multiplied by the Factor of Subdivision - which for a ship if this size and number of passengers would undoubtedly be around 0.33) i.e. a 3 compartment standard (the maximum required).

There is a possibility that the ship was built to the new probabilitic rules which have been available for naval architects to use under SOLAS 74 as an 'alternative subdivision method', but rarely used because of their complexity and lack of any intuitive guidance in placing bulkheads. It was at this time that the Required Subdivision Index was set as a mean line through a large sample of the then British passenger fleet including the QE2 (at the top end of the curve) and a large range of other passenger vessels including a substantial number of RO-RO ferries - an arbitrary way of estabilishing the basis for 'equivalence'.

Please note that the newer probilistic approach uses a number of different drafts and associated permeabilities than the maximum load draft of the deteministic approach (a pretty good estimate of a large passenger ship in its Loaded Departure Condition as the CC) and has a maximum damage length of 24% of the vessel's length (cf Titanic - the statistically maximum value!).

There are formal limits to the heel of the vessel in its damaged condition in that the survival index varies from 1 to 0 over the range of inclination from 12 to 27 degrees, thereby assuming that such ships may heel substantially - although minimum damaged stability characteristics must be achieved. These same rules have also applied to the deterministic approach to ensure the possible evacuation of passengers from vessels which have assymetric flooding or suffer initial instability in the flooded state. In such conditions it then must be demonstrated that no downflooding points exist that will result in further progressive flooding.

Please be careful to distinguish between elements of the regulations which are designed to apply specifically to damaged Ro-Ro vessels (the B/5 limitation and damage length rules) where the inherent risk of capsize is significantly higher and where the regulations are still considered by many to be lacking.

As you point out there is probably a 12% chance that a vessel such as this will be lost in a collision and in this particular case we see an example of that 12% band in action - foundering by whichever subdivision rules are applied!

 

In an earlier post I suggested that squat might have been a minor
factor that caused a change in the ship's attitude, and in particular it might
have caused the stern to drop more than expected.

Here's a link to an old article named "Why a Huge Liner Runs Amuck".

I think "squat" is a better name for the phenomenon than what some sailors
used to call it!

http://books.google.com.au/books?id..._esc=y#v=onepage&q=hydrodynamic squat&f=false

 

Not as worth watching as I thought it should have been. It did confirm the blackout as 10 minutes after the impact which would correspond to both engine rooms having been heavily flooded by then. It showed a number of watertight doors in what appeared to be the crew accommodation under the passenger decks left open in the early stages of the crisis and it seems that there was no organised attempt to clear these spaces and seal the bulkheads. The biggest technical mistake was showing a distribution of only 6 transverse bulkheads along the ship's length with 3 flooded - there should have been about 15 with 3 or possibly 4 flooded!

 

I thought the same - It didn't really give any idea of how the boat could have flooded so quick, or what led to the tilting - nor of how it was navigated in the loop back to the island using the momentum it had from before & moved towards the shore with the bow thrusters etc.

In terms of the number of watertight compartments, I've been told (by someone who worked on the construction of one of its sister ships) that it had 12 - which is about what I'd expected based on the size of the ship. I have no idea where the low figure they gave came from - it makes you wonder about how well researched the rest of the program was.

 

On gCaptain.com we've been debating the same issues. Pardon the length of this.

(1) Cause. Captain overrode safety alarms and more junior crew and hand steered in the dark for a close pass-by because he'd done it successfully 3-4 times before. He held course toward the island 30-60 seconds too long, didn't figure out he was off course, and hit the island at 2130 while BS'ing with other people on the bridge and his mentor on the cell phone. Unbelievably stupid and careless.
(2) Damage. Ripped open 160-200 feet of aft port side hull opening all five main engineering spaces to the sea, which quickly flooded, killing all power to props and ship except the emergency generator. Still had steering. With 5 of 16 WT compartments ripped open, all aft of amidships, this three compartment ship was doomed. The Chief Engineer informed the captain 5-8 minutes after striking the island that they had lost it. The captain's behavior and (in)actions are appalling and inexplicable to any maritime professional.
(3) Course: The ship coasted to a stop at 22:10 in a slow turn to starboard, just past the eye of the 12-15 knot NNE wind. The 100,000 square feet of "sail area" of its topsides then pivoted the ship around its sinking stern and it drifted back to Porto Giglio with the wind on the port quarter. The loss of waterplane area, the free surface of the 5 large flooded compartments combined with the vast sail area, CE at +50', gave it a starboard list at this point.
(4) Second Grounding: At 2246m at a speed of about 0.7 knots, the stern grounds first since it is about 20' below its normal lines, and the ship pivots to its final position against the island, with a list of about 20º and down by the stern. Some, but we don't know how much further damage is done to the starboard side. The captain finally declares a mayday 1 hour late, and abandon ship begins. Amazingly, over the next hour in spite of the 20º+ list, 23 of 26 lifeboats are successfully launched and loaded, evacuating about 4000 of 4300 passengers. During this time the list increases to about 30 degrees and the stern sinks to the level of the boat deck, the 3rd passenger deck. All this can be seen on the AIS charts and night photos of the ship and the one poor published cross-section.
(5) Capsize: (My best scenario so far, with help from others, it is hard to figure, I'd love more ideas about it.) Grounding at the stern, the ship is resting on the narrow taper by the aft thrusters and props, close to the centerline, not its broad bottom or starboard bilge. The bow is still floating but losing buoyancy flooding from below, biased to starboard, as WT bulkheads are overtopped. The lowest passenger deck, 3 decks above the waterline has an open mooring deck at the stern for line handling. This leads into two long corridors running the length of the ship, P & S, plus a large stairwell. With the stern sunk down to the boat deck (5th deck above the WL) this is open to the sea with 10-20 PSI pouring water into the starboard side cabins and spaces, which vent, and trapping air under the port side decks due to the list, creates a growing instability that rolls the ship around the narrow stern bearing point. Within an hour, capsize to starboard, initially to about 85º, but as the rest of the ship fills and sinks, settling to 70º to match the bottom. The surviving 300 or so crew and passengers walk off the sloping sides or are lifted off by helicopters.

The saving grace is that the vast highly subdivided internal volume of the ship took a long time to fill, and once grounded it prevented the ship from sinking by the stern and upending. By way too close of a margin.

We've argued about wing tanks, fuel tanks and other side or double bottom tanks that could cause the rolling moment, but have no real information, same for damage to starboard bilge. No real data re the plans or designs below the passenger decks, just one poor cross section.
Do any of you have more design info or other good scenarios? We sailors and ships engineers would like some design perspective. Thanks

 

I have no further info on this ship unfortunately - I've seen a lot of drawings for ships older than this (early 1990s), but these are a couple of generations before in terms of ship size, so I doubt that there is that much similarity.
I know though, that people who had more knowledge of the design of this one, said that they thought (prior to the incident), that it was as close to unsinkable as any cruise ship could be...

In terms of the number of compartments that were flooded, one thing that puzzles me, is that the captain initially informed the ship's owners that only one compartment was was flooded, later changing that to two, nearly 10 minutes after. At no stage until he stated the he planned to abandon ship, did he ever indicate that any more than two compartments were flooded.

This suggests, that either he blatantly lied, or that whatever indicators there are for flooding within the compartments were not functioning correctly.

See article here for the source of this information:
http://online.wsj.com/article/SB10001424052970203806504577183222389672472.html

 

There is some assumption on the damage length in SOLAS 1974 (deterministic rules), but which should be considered in conjunction with compartment permissible length.

Reference :
SOLAS 1974 as amended, in force up to 1/1/2009, therefore corpus of rules to be applied to "Costa Concordia" (built 2006).
Chapter II-1 part B
Regulation 8 (stability of passenger ships in damaged conition) §4 =
Assumed extent of damage shall be as follows:
.1 longitudinal extent 3m+3% of ship length or 11 m whichever is the less (=> 11 m for CC)
.2 transverse extend one fifth of breadth (B/5) (=> approx. 6 m for CC)

As you mention it in your post, that doesn't mean that the vessel will not survive an actual damage of more than 11 m. The assumed extent of damage has to be foreseen everywhere on the length of the vessel, including on a transverse bulkhead which leads to two compartments being flooded. Then we come back to the permissble length consideration.

There is still to know if the vessel standard is 2 or 3 compartments.

Francois-Xavier Nettersheim

 

You are right and your statement is very interesting, in particular when you mention the arbitrary way of establishing the basis for "equivalence" (the ships sample used was far too small).

The probabilistic rules you refer to and which could have been used for "Costa Concordia" is the old IMO Resolution A 265 dated 1973 (as an alternative to deterministic rules of SOLAS 1960 and later SOLAS 1974). I doubt that "Costa Concordia" designers used this set of rules in 2004/2005 when they were calculating the vessel.

The new probabilistic rules, the so-called SOLAS 2009 (in force since 1/1/2009), are quite different. Roughly speaking we may say that they have no more requirement in terms of sunking limit for they have no concept like the old margin line. This is not completely true obviously. But the question of the disparition of the margin line is on the table.

I hope that some scientific research in a near future will try to determine what would have been the attained subdivision index (A) of "Costa Concordia" calculated according to SOLAS 2009.

Francois-Xavier Nettersheim

 

Barred the door, I will try to enter from the window.

Introduction.

In 1894, a time when the largest ship had a tonnage of only 13000 tonnes, the British Ministry of Commerce (Board of Trade) decreed a regulation that pondered the presence of lifeboats, whose capacity was calculated based on the volume: this volume depended on the tonnage of ships and not by the number of people transported. In 1912, this regulation, which was not updated according to technological progress, which resulted in a sharp increase in the size of ships, was obsolete as the tonnage of the largest vessels now exceeds 46000 tonnes, as happened to the Titanic. The regulation was to provide that the British ships with a tonnage exceeding 10000 tonnes were to be equipped with 16 lifeboats with a total capacity of 5500 ft3 (feet) that is equal to 155.7 cubic feet and a sufficient number of boats that tend to increase the 75% the capacity of the boats. The total capacity of the boats was thus set for a 9625 ft3 (272.5 m3). Because it was thought that a person occupies a volume of 10 ft3 (0.283 m3), we can deduce that it was the equivalent of 962 people.
intelligenti pauca

Conclusions

The number of persons on board a cruise ship is increasing dramatically.
Ships have exponentially increased their ability to embark passengers (economies of scale).
In addition, larger is size of a boat, greater the attraction that it generates towards certain groups of clients.

On this TD talking about refresh rules of design seems a blasphemy.

WHY?


ANSWER


Gian,
The consensus seems to be that:

1.) This accident was caused by idiocy, not a technical failing of the vessel or design rules.

2.) Despite repetitive idiocy, the ship performed very well and sunk in a controlled manner, so not much call for a re-thinking of the rules.

3.) What this accident really highlights a need to review the process of becoming a captain of a ship carrying so many people, and perhaps better training and screening of crew as well.

Lives are precious, but in a world of finite resources, we have to make cold decisions about where best to expend our energy, and be wary of drawing the wrong lessons from events.

------------------------------------

NO COMMENT?

 

Captain Lied

Mat8iou, The 3rd & Chief engineers testimony said they saw five compartments flooded or uncontrollably flooding and informed the captain about 5-10 minutes after hitting the island. The third saw it as so hopeless that he went to his emergency station.

The Captain's statement to the home office was false. Maybe only one or two compartments (main engines) were fully flooded at +5 or +10 minutes, but he had been informed the others were lost too. Minimizing the problem & wishful thinking seems to have been his habit.

 

They appear to have lost 3 times as many people this morning (20120202) in a ferry off Paupa New Guinea. If all lives are equally precious, where should the IMO and MSC be putting it's efforts? Into ensuring that compliant flag states spend millions of euros to reduce the lives lost to an unachievablely low number (the old "total quality improvement" paradox)? Or into trying to coax grater safety into marginal flag states? Please put a number on it; how many euros is each Dane, Swiss, Italian, Indian, Bangladeshi, Papua New Guinean, Malaysian, Ghanaian, etc, worth in expendature of international monies? Then we can figure how many people transit in each country by water, total up the loss percentage and come up with the 10 best place to spend the money. I have a pretty good idea where it isn't....

 

I am interested to know how you can state the 5 of 16 WT compartments were flooded? Mat8iou on the Simulating Costa Concordia Thread is equally sure that it only had 12 compartments along its length.

Given the fact that it approached the shore after some 1.5 hours with nothing more than what appears to have been sinkage, trim and a 'loll' of some 15 - 20 degrees - to port initially and only later to starboard (possibly after the impact with the shore), I find it unlikely that more than 3 (for which it would have been designed under SOLAS Regs) or at most 4 of its compartments were flooded.

Such conditions would have allowed ample time to evacuate the passengers without the chaos after grounding if the captain and his officers had not ignored the obvious!

With the less than professional actions of the crew it would seem that watertight (below the passenger decks) and external weathertight doors were left open which would undoubtedly have resulted in eventual foundering if it hadn't grounded.