collision of MSC Chitra X MV Khalijia III - the danger caused by floating containers

The calamitous news for India is the collision of MSC Chitra with MV Khalijia-III at around 0930 am on Aug 7th ; first there was disturbing news of oil spill, then JNPT rendered non operational due to the mishap and then the news of hundreds of containers floating in the sea lanes close to Mumbai shore. The closure of JNPT & Nhava Sheva disrupts Indian economy in a big way – reportedly 17 ships were stranded and 15 more waiting to dock following the shutdown of the ports. MSC Chitra had 1219 containers on board of which 31 were hazardous chemicals and pesticides.

MV Khalijia 3 owned by Kuwaiti Gulf Rocks Co was able to safely dock after the collision. MSC Chitra is dangerously listing and oil is spilling out from her fuel tanks. Listing refers to ship leaning on one side caused by uneven loading or flooding. At the time of mishap MSC Chitra had 512 containers on deck and 707 below the deck. The Port Trust authorities contracted the vessel agent and Insurers & P&I club. Smit Slavage, Singapore were appointed for salvaging the vessel. The vessel dropped anchor and secured from drifting but listing increased and about 250 containers have fallen into the sea.

The Indian Navy carried out a survey of the main channel and for surveying the containers that had hit the bottom, all ship movements have been stopped according to PIB. The floating containers are being cleared with the help of tugs and floating cranes. Once the vessel stabilizes and certified safe, salvors would board the vessel, remove the fuel into barges. The imminent threat of floating containers has already had its toll as one container banged into a sand barge near Elephanta island off Mumbai. Another report has it that 10 people had miraculous escape when their boat capsized after being hit by a container.

Now the primary question in one’s mind is whether the containers would sink into the sea immediately or float ?

The TEU of 20’ box has a volume of over 38 cubic meters ; sea waer is 3.5% heavier than fresh water and generally is around 1030 kg per cubic meter. For a container to sink the water force should exceed the volume of water that is displaced. Thus, theoretically, a container would float. However, containers are not water tight and are not singularly built objects – the sinking is directly proportional to the water entry.

To understand ISO containers are after all boxes which typically has doors fitted at one end and generally made of corrugated weathering steel. By definition, container must be of permanent character, strong enough to be suitable for repeated use; specially designed to facilitate the transport of goods, by one or more modes of transport, without intermediate reloading; designed to be secured and/or readily handled, having corner fittings for these purposes; of specified sizes. They are not made of single material but various material combinations which include steel, aluminum, wood and plywood.    By design, the load carrying element is of steel frame work having corner posts and bottom side rails, top side rails, cross members and a top end rail and door header. The side end walls and roof besides the floor are capable of bearing load, which goes by the material used in construction. Walls and roofs are generally made of steel sheet, corrugated, aluminum sheet, sometimes glass fible reinforced ; doors age generally of plymetal or corrugated steel. Floors are generally made of wood / wooden planks and have to be capable of bearing the evenly distributed payload. Though the dimensions might vary, the dimensions generally of Length : Width : Height could ; 20 ft (6.1m) : 8 ft (2.6m) ; 8.5 ft (39 m3). The tare weight is around 2400 kg and the payload is 21600 kgs. There is possibility of containers being overloaded also.

The expert opinion is that most containers do sink immediately – this is compounded by various factors such as poor maintenance, distortions, holes etc., Thus, though there may not be a specified time frame for sinking of these containers laden with cargo, their floating for a longer time is generally not possible. Some do float and reach the nearby shore. It is also opined that empty containers will take water through vents, seals, flooring and damaged places and would sink faster. Containers with little weight tend to float for longer time. It is also stated that it is not physically possible for a container to totally immerse and freely float some distance below the surface.

Thus, the container will sink into the sea where the weight of water displaced ; the water that goes into the container increases its weight. However, as this collision occurred closer to shore and to the Port, situation is somewhat different………………

Strange things always happen at sea..

Regards – S(rinivasan) Sampathkumar