Capsizing of COSTA CONCORDIA and fire of engine room on board CARNIVAL TRIUMPH show that hundred years after tragic sinking of the ocean liner TITANIC passenger ships are still not sufficiently safe. “Safe Return to Port” means new SOLAS regulations applicable to new passenger ships having their keel laid on or after 1st July 2010, and having a length of 120m or more, or having 3 or more Main Vertical Zones. As per these regulations, a passenger ship shall be designed so that the essential systems remain operational after a fire casualty which does not exceed casualty threshold or a flooding of any single watertightcompartment and the ship is able to proceed to a safe port under their own power. This may sound simple in theory, but in reality poses a real challenge to ship designers.
A casualty threshold includes a loss of space of fire origin up to the nearest “A” class division if the space is protected by a fixed fire-extinguishing system, or a loss of the space of origin and adjacent spaces up to the nearest “A” class divisions which are not part of the space of fire origin if it is not protected by a fixed fire-extinguishing system.
During this “Safe Return to Port” period, all persons onboard are accommodated in a “safe area” where basic services for their safety and health are available. Safe areas are spaces (generally, internally located) where basic services such as food, water, sanitation, alternate medical care, lighting and ventilation are maintained.
If the casualty threshold is exceeded, SOLAS now requires some essential systems to be still operational for three hours in order to support the “orderly evacuation” of the vessel, considering one entire main fire zone lost.
However, it is necessary to understand that in case of long shallow side shell damage, ships without double sides in way of machinery spaces will capsize in the same way as COSTA CONCORDIA, even if built according to SRtP rules.
Further reading: MSC.1/Circ.1369 INTERIM EXPLANATORY NOTES FOR THE ASSESSMENT OF PASSENGER SHIP SYSTEMS’ CAPABILITIES AFTER A FIRE OR FLOODING CASUALTY