Parametric rolling, and lashing errors were the cause of the three
stack failures on the CMA CGM G. Washington, resulting the loss of 137
containers and damaging a further 85 boxes, according the Marine Accident
Investigation report (MAIB) released this week.
According to the MAIB accident analysis, the vessel first rolled 20°
to starboard, paused for several seconds then rolled 20° to port, during the
early hours of 20 January 2018, in heavy seas in the Pacific Ocean.
Stack collapses almost certainly happened
during the parametric rolling say MAIB investigators; master failed to identify
the risk of parametric rolling
MAIB investigators concluded that the stack collapses almost certainly
happened during the parametric rolling, which caused extreme pressure on the
“The risk of parametric rolling was not identified by the master or
his bridge team because they were unaware of the full capabilities of the
decision support tool, and therefore were unaware of its predictions,” said the
However, the report also concluded that the reduced structural
strength of non-standard 53ft containers in bay 54, inaccurate container weight
declarations, mis-stowed containers and loose lashings.
Acceleration forces exceeded for the
non-standard 53ft container
Acceleration forces and the bay plans conducted by Bureau Veritas
calculated that the acceleration forces acting on the containers in bays 54 and
58 were within the limits for ISO containers, but exceeded those for the
non-standard 53ft container.
Conclusion by the investigators
The investigators concluded that, “The corner post load limit for 16
of the 17 rows in Bay 54 was exceeded, and the racking force limit was exceeded
in four rows. It was therefore unsurprising, during the initiating roll on 20
January 2018, that most of the non-standard 53ft containers suffered structural
failure, causing the remainder of the bay to collapse.”
The collapse of the non-standard containers in bay 54 led to the stack
failure in the adjacent bay 58, as falling containers caused a ‘domino effect’
knocking more boxes from their moorings as they fell.
containers lost overboard, and 17 boxes damaged as the stack failed
Some 24 containers were lost overboard, and a further 17 boxes were
damaged as the stack failed, but the report also highlighted the failure of the
twistlocks in the bay as the safe working loads (SWL) of the fixtures were
exceeded. A phenomenon that also featured in the analysis of the failure of bay
The investigation determined that several twist locks were recovered
and investigators found that the SWL on the twist locks had been exceeded, but
that the loads on the fixtures were less than the manufacturer’s design proof
and breaking loads.
Misdeclared container weights one of the
contributory factors for stack failure
Although the investigation into the collapse of bay 18 was
inconclusive, the report said that there were a number of contributory factors
into the stack failure, including misdeclared container weights, weight
distribution, the lashing arrangements and the condition of some of the
The structure of some of the containers was poor and this lead to a
collapse of the load, as the containers collapsed they moved sideways, into the
next stack pushing each column of containers outwards until the outer column
was pushed over the side.
In conclusion the MAIB reported, “Given the reliance placed by the
ship’s crew on the ship’s loading computer when judging whether a container
stow is safe, it is essential that input data for container strength accurately
reflects the CSC [Convention for Safe Containers] data for each container
loaded, particularly non-ISO containers.”
Cargo planners could not access CSC
information; databases not fully populated
Furthermore, the report said that cargo planners could not access CSC
information on individual container types through the Bureau International des
Containers, Global Container and Approved Continuous Examination Programme
databases, what is more these databases are not fully populated as some
countries have not supplied data.
“The UK is one of the countries that has yet to contribute to this
database,” said the report.
Final cargo plan was not updated
Moreover, the final cargo plan was not updated to reflect the
container weights measured in the terminal, in accordance with guidance from
the International Maritime Organization, the Maritime and Coastguard Agency and
World Shipping Council.