200923 Concentrate liquefaction caused capsize

Concentrate liquefaction caused capsize
MARS Report 200923

Official report: adapted from IMO FSI report, 11th Session

A small general cargo vessel was loaded with a bulk cargo of 6,000 tonnes of pyrite concentrate. Soon after leaving the port, the cargo liquefied, forming a free surface and causing a severe list (angle of loll). The crew made several attempts to correct the list by ballasting, without success, with the vessel taking a severe list first to one side then the other. Eventually it capsized and sank. All the crew, however, were rescued.

Root cause/contributory factors
The moisture content of the cargo was excessive;
The cargo had been rained upon while on the wharf before it was loaded;
No moisture tests were carried out before loading and no information regarding the characteristics of the cargo had been provided to the shipowner or the master;
Once agitated by the motion of the ship, the cargo underwent liquefaction;
By ballasting incorrectly to correct the list, the ship's staff made the problem worse, until the vessel eventually capsized.
Lessons learned

All relevant information on the characteristics of the cargo being carried, including the transportable moisture limit (TML), must be provided to the shipowner, master and officers who must all make themselves familiar with this information.
When transporting cargoes subject to liquefaction, the moisture content of the cargo must be measured as close as possible to the time of loading.
The cargo must be inspected before loading.
Ships' officers should have a thorough knowledge of stability, particularly the difference between a static list and angle of loll caused by free surface and the appropriate ballasting measures to adopt
Do not correct a list due to free surface (angle of loll) by ballasting the 'high' side.
Editor's note: All dry bulk cargoes must be transported strictly according to the recommendations in the bulk carrier (BC) Code. Concentrates and similar bulk cargoes that may liquefy are listed as group A cargoes and the Code specifies procedures and precautions to be taken by the shippers and masters of ships to ensure safety.

In many regions, such cargoes are loaded in anchorages from specially constructed barges that are capable of carrying these materials in a very 'wet' state. Even if pre-shipment documents are provided in good time, it is common for these ships to complete loading and sail without supervision or support from shore-based marine safety authorities and experts. Before commencing to load concentrates from such ports, masters should inform owners and their P&I Club representatives to ensure good liaison with shippers and to ensure proper sampling and testing of the bulk cargo ashore.