On 31 March 2017, the 322 metre long, 266,141 dwt VLOC bulk carrier Stellar Daisy sank in the South Atlantic Ocean on route to China. With 22 of the 24 crew members of the very large ore carrier Stellar Daisy still missing, many in the shipping industry have been asking why the vessel reportedly split and sank after taking on water following a hull crack 2,000 miles off Uruguay. The investigation is expected to take a long time and is likely to be inconclusive, but we do know that six serious deficiencies were found in the vessel this February but it was allowed to sail without any detention.
However, even as the actual reason why this incident took place remained unclear, some insurance officials pointed out that the speed of sinking and the high loss of life mirrored casualties related to liquefaction of cargoes such as iron ore and nickel ore.
With a high moisture content, iron ore has a propensity to liquefy during a voyage, which causes serious stability problems with a high possibility of capsizing. “Incidents due to liquefied cargoes can lead to serious perils, as the liquefied slush mounts quickly, brought on by vibrations and motions of the vessel, and the ships sink fast,” said a P&I club official.
“The wet cargoes change their state from ore fines or mineral concentrate to a viscous fluid that can undermine the balance of the ship.”
London P&I club says in its new guide on managing the risk of cargo liquefaction that the liquefied cargo can flow to one side in a roll in heavy seas, and that it would not return with the roll the other way, which progressively leads to the vessel capsizing.
Consignments that are prone to liquefying have to undergo proper testing of moisture content before being loaded, a measure described under the International Maritime Solid Bulk Cargoes Code.
The code as it stands would possibly prevent many incidents due to liquefaction if it is followed strictly, as it sets out a maximum moisture content of the cargo which is considered safe for carriage in ships, known as total moisture limit.
The onus for these lab tests lies with the charterer, as it must provide the master of the vessel with written evidence that the moisture content does not exceed the TML. Upon the failure to provide such a certificate, the master should not load the cargo, said a Singapore-based vessel owner and operator.
“But unfortunately, the results from these tests are sometimes modified and false figures for the moisture content are presented, which leads to emergencies,” he said.
“However, the lab centres have an obligation to keep the sample of the cargo inspected by them for a period of two months,” he conceded, adding that in the case of Stellar Daisy this could provide essential evidence for an investigation.
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Last updated: 10/04/17