The Costa Concordia sinking was shocking incident, not only because of the accident itself, but because it showed that after all that has happened since the Titanic that the Maritime Safety bodies, cruise ship designers and ship owners can still manage to completely 'screw the pooch' as were on passenger safety.
I could not believe my ears and eyes when I heard and read reports that the maritime safety organizations consider the ship itself as a ' life boat' to be used in an advent of an emergency and the crew are to try and return to port or safer waters. Especially the largest of ships over 100,000tons.
All this 'idea' accomplishes is to delay the loading and safe launching of the true lifeboats. This delay WILL BE fatal as any delay in launching the life boats will be effected by the inevitable listing of the ship that could stop up to 50% of the life boats from safely launched and under current guide lines that a loss of 62.5% of the life boat capacity the people on board will not have safe access to all of a PRIMARY life saving device.
To control the flow of water into the a ship of you have to have sealed compartments inside the hull not only across the hull, i.e. sealed bulkheads, you have to also seal the ship longitudinally as well with multiple water tight compartments within these zones, between the main bulkheads. You cannot have a mass of water sloshing from side to side with the action of the hull. Eventually enough water collects on one side in one moment and the ship capsizes.
The fact that the Costa C capsized to the opposite side of the hull breach shows that this modern ship may have had 5 main water tight zones, it did not have any other passive means of controlling or where the water went. It obviously had free access to flow across to the other side of the ship.
This is exactly what studies into the behavior of free flowing water inside a hull of a ship found. These studies were part of the investigations by Dr Bullard’s team when they were investigating the behavior a sinking ship as part of their Titanic project.
This investigation in part looked what happened to the Titanic in actual fact, if the ship had hit head on, and what would have had happened if there were no partition of the hull if damaged as she was, and head on damage to bow only with the above listed hull designs and conditions.
The conclusions were that the existing water tight compartments delayed the sinking a factor of 50% when compared to having no bulkheads. That with out bulkheads, the ship would have capsized unpredictably and develop a listed early on in the process and if the weather had a larger sea state the ever increasing movement created by the body of water inside the ship would stop the safe launching of any lifeboats.
At this point two factors of buoyancy and stability need to be explained; PRIMARY Buoyancy /passive stability which is the ability of the ship to be stable and afloat with no other input in calm water.
The other is called SECONDARY Buoyancy / active stability which is the measure of the ship's ability to float and be stable under different weather states and conditions with the crew using active measures to improve stability. Flooding decreases this factor, as does high sea state and improper loading of the ship. The use of engines, active stabilizer and the ability to move liquid ballast about in sided the hull which is also called counter flooding if the hull is breached improves stability.
When the' weight' of the negative factors reach a point that the Primary Buoyancy / stability is overcome by these factors the ship capsizes and sinks.
The one important factor inside this equation is ships power. Any ship caught out in the open sea in deteriorating conditions is in with a good chance of sinking if it loses power.
I personally know of only one ship that has a portion of it ships power out of reach of flooding is the QM2
Now back to the Costa c, this accident and most other loses of modern cruise ships have early on the time line lose main engine power, so the any ability to control the ships behavior is lost too. Not once has a cruise liner been able to stay afloat from a impact and hull breach on it sides.
So where this idea came from, from what evidence they were able to use to define that the crews had the necessary control to allow a now seaworthy vessel can be a suitable 'lifeboat' is completely beyond me.
Any ship that has uncontrolled flooding is not seaworthy and I donot believe the Costa C had any more than basic ability of controlling the flooding and no ability at all to passively limit flooding to allow for counter flooding, even with the ships power in a working state.