Costa Concordia, 80 deg list, really scary !!

Tad, Primary VS Secondary ain't that hard to grasp.

A dory has low primary, but high secondary.

It will wont resist rocking back and forth, or beginning to tip, but will resist going all the way over, because once you tip it past a few degrees the below the water line hull shape changes AND you got a big mass out of the water and far from the pivot point on the high side.\


A low sided Jon boat will have high primary, low secondary. I suspect these cruise ships are like Jon boats with tall stack.

 

- ideal for most rowboats and canoes. A wave passes right under the boat without rocking it but if you try to tip it over it goes so far then resists, hopefully stopping before it fills up . . .

 

Everything you said Lister is true, but I have gone on at least a dozen cruises with my family and we all had a very good time for relatively little money, and never had a single incident of any kind. I have flown all over the world with similar experiences. On my personal boating life, I have run aground more than once, had to beach a sinking boat twice, got hit by lightning, been through 40 foot swells, shot at, boarded by CG several times, and seized once. So is cruising safer than boating???

 

Carnival being sue in the US
http://www.businessweek.com/news/2012-01-27/carnival-sued-in-u-s-over-costa-concordia-disaster-in-italy.html

Mydauphin I am very please you had good time. A lot of people had good time flying and cruising. It is a way to have good holidays.
The problem is on the morale quality of the management. If something go wrong on a cruise ship, the domino effect is horrible.
A cruise ship should be with a maximum of 1000 passengers and all being capable of north Atlantic winter time.
the number of deck should be reduced, and the number of life boat augmented, and sufficient for all in each side.
The different meting disaster point should provide the life jackets, going back to the cabin retrieves it can be a death sentence. The crew, ANY members should be hired year round, and fluent in English. Even the bass boy should know how to extinguish a fire.
The captain should be accountable on the highest level, and the owner criminally responsible if death occur due to lousy navigation.
The electric engines should not be on pods, since they can be repaired at sea, the numbers of diesel engines should be reduced to don't overwhelm the mechanics.
The list of changes on the regulations is very long ( Well the Lister list )
Honestly some cruise lines implement the above list.
so I just stop there.

 

Once again Lister, I agree with you on the list too. I would rather go on a cruise with 1000 passenger ship over a 5000 passenger anytime. Every time you have to get off or on a one of those big ships it takes times. You always have to arrive early from shore trips and the line still around the block in many cases. I would hate to think what would happen to evacuate one of those big ships.
Oh just a gut feeling, in a major fire or flooding, the crew is racing the passengers to see who can get out first. Why would they stay?

 

I think you're right - in the Costa Concordia, the Captain won the race!

 

A couple of kayak designers are the only people I can find using these terms, they are not used by naval architects that I've come across. Initial Stability refers to lower angles, beyond that it's all just the range of stability. Secondary could refer to high angle or ultimate stability. The words low and high are meaningless unless related to some absolute, which doesn't exist when looking at xxxxxx vessel.

 

I'm late to this thread, and have a few pages to go -- but this would be interesting. Even a guess would be interesting. Maybe I'll find it if I keep reading ...

 

Even a guess would be interesting. Maybe I'll find it if I keep reading ...

NA Professor I.E. Winkle worked out a good approximation of the KG in post # 20
at:
http://www.boatdesign.net/forums/boat-design/simulating-costa-concordia-41365-2.html
You will find more general info at:
http://www.boatdesign.net/forums/al...voyage-costa-concordia-cruise-ship-41313.html

 

Evacaution of such a ship (even with a slight list/loll) with all the passengers at their alotted boat stations should take little more than 10 to 20 minutes under an 'orderly' evacuation procedure as all boats can be lowered more or less simultaneously after loading their 75 or so passenger allocation. It is a different matter getting 3200 passengers down a single gangway to the shore! If you leave it loo late and the loll rises to 25 degrees or more, half your boats are useless! The hour long delay in this case led directly to the loss of many of the passengers.

 

I think you will find the energy of this impact was very similar to that of a topedo explosion and over a much longer length (due to the racking nature of the impact). A thicker hull would make little difference. The nature and length of this damage is extremely rare (hence the Titanic comparison) and ships are never designed to survice more than approximatley three transverse compartment flooding. Damage more than that and the ship will sink - the function of the naval architect is to try to ensure that in such a condition the vessel will have sufficient reserve of stability and time afloat to evacuate all the passengers. 1hr 15 mins to grounding was more than enough time to accomplish this with a properly trained crew if the order to abandon ship had been given shortly after the damage occurred (clearly notified by the crew in hte flooded engine rooms). Failure to act by the Captain and crew is not the responsibility of the designers or the IMO Regulators (SOLAS).

 

Please do not confuse the loss of cargo ships with those carrying fare-paying passengers. Until recently all SOLAS regualtions related only to those ships carrying more than 12 passengers. This was on the principal that small professionally trained crews of cargo vessels could evacuate a sinking cargo ship very quickly and understood the risks and dangers involved. Passengers will always tend to panic if required to evacuate a ship, having received no formal training in evacuation procedures (other than one hopes the position of their lifeboat station and how to put on a life jacket) and therefore they are the resposibility of the trained crew in any evacuation. If the crew fails in that duty then they must share some of the responsibility for any loss of life. The lack of a passenger lifeboat drill in this case must also be a contributary factor!

 

This ship behaved exactly as you would expect for a large passenger vessel severely holed below the waterline over something like 20% of its length. It slowly sank a little, trimmed by the stern and lolled to an angle of 10-20 degrees over the 1 hr 15 mins up to the point of grounding. Most competent ship's crew would have been able to get all their passengers off into the lifeboats in that time with little risk of casualty given the relatively calm conditions at the time despite the loll (part of the requirements of SOLAS regulations) and easily accomplished with this vessel's davit system. An incompetent crew (officers at least) delayed doing anything for an hour and were forced to evacuate as the vessel rolled to extreme angles on the shore probably because extra holes had been openned in the starboard side of the hull on the rocky slope as it grounded.

 

Thank you Professor Winkle for joining this Forum. I am sure many members appreciate your pertinent posts as much as I do.
One of our junior NA in the Houston US office is trying to build a computer model of the ship (on his spare time) and will run a number of intact & damage stability conditions once the model is ready. He said it will take time since he hasn't been able to locate good machinery & tank arrangement drawings . We will need more of your expert advice at that time.

 

Oh, I am at no misunderstanding of the survival differences between cargo, passenger, and war ships, unlike some who have contributed to this thread. Rather what I was trying to bring out in the quoted comment is that the number of people lost and/or missing in this casuality is not a dire call to changes, but rather, when compared to as you say "small professionally trained crews of cargo vessels", light. Even lowballing the number aboard as 4000 and assuming 17 dead and 20 missing that puts the loss at under 1%; would that merchant losses be so light. Even considering that there was no lifeboat drill, almost all people were able to abandon, and grounding cuts both ways in that it reduced the time to abandon as well as providing a close safe refuge.

I, similiar to you in http://www.boatdesign.net/forums/boat-design/simulating-costa-concordia-41365.html#post523010, think that the ship would have sunk anyway and may have "capsized" towards the end (though can a ship really "capsize" if it has turned into a spar buoy?, though it may have had hull girder failure like the RMS Titanic). However my experience with cruise ships is that BM is much lower than one would expect due to the free surface these vessels have in thier tanks and pools. Additionaly, the GM is nowhere near 2m, as that would render the ships uncomfortable and the stablizers much less effective and KG is fairly low due to arrangements, tankage and stores (see my discussion here).

What I really wish to point out is that the design and requirements levied on cruise liners like the Costa Concordia reduce the risk of dying to less than the risk of dying while traveling to the ship by either car or air. These ships are as about as safe as traveling gets. No method of travel is perfectly safe, but ships are far safer than aircraft, and ships cannot be made any safer as long as the command team fails thier duty runs it into something at speed. As I have said before, you cannot make a ship sailor proof.