Weight distribution, lashing arrangements and ship motion main causes of Ever Smart container stow collapse: MAIB

The UK Marine Accident Investigation Branch has said in its report on the container loss from the Ever Smart (IMO 9300403) on October 30th 2017, while she was 700 miles east of Japan, travelling from Taipei, Taiwan to Los Angeles, USA that the container stow collapse was caused by a combination of factors; in particular, container weight distribution, container lashing arrangements and the ship’s motion.

The master had changed the ship’s passage plan to avoid severe weather caused by a developing depression east of Japan. The 7,024 teu Ever Smart continued in heavy seas; rolling and pitching heavily, with frequent bow flare slamming.

Following the company’s heavy weather procedure, the crew were confined to the accommodation block. The following afternoon, once the weather had abated, the crew discovered that the container stacks on the aft most bay had collapsed and toppled to port. Of the 151 containers in the stow, 42 were lost overboard and 34 were damaged. Superficial damage was caused to the ship.

The MAIB investigation concluded that:

  • The loss of the containers most likely occurred during a period of heavy pitching and hull vibration in the early morning of October 30th.
  • A combination of factors resulted in a loss of integrity for the whole deck cargo bay; in particular, the containers were not stowed or secured in accordance with the cargo securing manual.
  • The container lashings might not have been secured correctly.

MAIB noted that it was “essential that tier weight restrictions are followed and are not ignored, even if the overall stack weight limits are not exceeded. That was clearly not the case for bay 70; the weights of the containers allocated to the upper tier slots exceeded the indicative limits provided in CSM stack weight tables, and the weights of those in the lower tier slots were well below the limits.”

Ever Smart’s C/O used the ship’s loading computer to calculate the ship’s stability, the forces acting on the hull, and to check the cargo stowage and lashing plans. The central planners ashore used the same version of software. The ship’s loading computer identified that the lashing pattern selected by bay 70’s stowage plan was insufficient. Some load limits were exceeded by 150% in both outer stacks. The CSM was not referred to.

Weakness in the lashing arrangements was evident when the ship arrived in Los Angeles. Of note:

  • The wind lashings in the outer stacks of bays 50, 54, 58, 62, 66 and 70 had not been applied (Figure 31).
  • Several lashing rods were found to be loose.
  • The lock nuts had not been applied to many of the lashing rod turnbuckles.
  • Some twistlocks appeared to be heavily corroded.

The bottom container in Bay 70’s starboard outer stack was of particular interest during the investigation as the collapse was almost certainly initiated in that row, and it was the stack’s only container that suffered significant damage. Like most of the containers in tier one of the adjacent rows, it suffered buckling damage to its forward inboard (port) corner post. Its outboard aft bottom corner casting was also torn away from the frame of the container.

Following the accident, Evergreen Marine Corp. (Taiwan) Ltd. issued a fleet circular reiterating the need for ships’ masters to manage heavy weather encounters effectively.

MAIB said that it was likely that the accident occurred at the time the hull vibrations and frequency of stern shaking were at their worst. The vibration was probably the result of whipping forces transferred through the hull as the ship’s bow slammed into the sea.

The gale force wind was acting directly on the starboard outer stack, and its effect would have been significantly amplified due to the increased height and lack of the additional wind lashings prescribed in the CSM.

Recommendations have been made to Evergreen Marine Corp. (Taiwan) Ltd to improve standards of stowage plans produced ashore, knowledge of the dangers of bow flare slamming and lashing gear maintenance management.

MAIB noted that “most container stow collapses of this kind occur following the structural failure of an individual container within the stow or the failure of the lashing arrangements. In either case, the containers in the stack directly above the deformed or unsecured container will topple sideways into the adjacent row. This leads to a domino effect as one stack hits another, causing structural or lashing system failure in each adjacent row. This sequence of failure will continue until the outer stack is reached and containers are lost overboard. If the individual weight of any container in a stack exceeds the limit given in the CSM (Cargo Securing Manual), there is a risk that the lashing devices will become overloaded and will fail. Similarly, the risk of containers suffering compression or racking damage lower down in the stowage will also be increased.”

MAIB’s recommendations highlighted to the company’s ship masters the increased risk of cargo damage when ships experience hull slamming and stern shuddering during heavy weather.

Further, it should introduce a programme for lashing equipment inspections when the ship is not in service; and action should be taken to ensure shore planners are fully trained in the use of ship loading computers and that they understand the importance of checking permissible load limits for containers and lashing systems.

2006-built, UK-flagged, 75,246 gt Ever Smart is owned by A&L CF March 5 Ltd care of manager Evergreen Marine (UK) Ltd of London, UK. ISM manager is Evergreen Marine Corp of Taoyuan City of Taiwan. It is entered with Gard AS on behalf of Evergreen Marine (UK) Ltd. For H&M it is entered with Evergreen Marine Corp (Taiwan) Ltd.

Full report:

https://assets.publishing.service.gov.uk/media/5f15a2993a6f405c0f80ac37/2020-14-EverSmart-withAnnexes.pdf