LATELY we have seen a spate of containers being dislodged or damaged on-board container vessels transiting the North Pacific Ocean. For instance, since November 2020, five container-loss incidents have been reported on vessels involved in trans-Pacific crossings: ONE Aquila (approximately 100 containers), ONE Apus (approximately 1800 containers), Ever Liberal (approximately 40 containers), Maersk Essen (approximately 750 containers) and MSC Aries (approximately 40 containers).

Whilst there has been speculation that ultra large container vessels (ULCVs), which have a capacity in excess of 15,000 TEU, might become prone to lose or damage containers on deck in inclement weather due to their sheer size and dimensions, all the vessels involved in the North Pacific had a capacity of less than 15,000 TEU. The only ULCV container-loss incident so far has been the MSC Zoe (capacity 19,224 TEU), which lost 342 containers overboard in January 2019 in the North Sea during heavy weather. The Dutch Safety Board, the German Federal Bureau of Maritime Casualty Investigation and the Panama Maritime Authority (flag state of the MSC Zoe) have conducted an in-depth report (and accompanying video) which can be found here. It offers a sobering look at all the factors that contributed to the loss of the containers.

Incidents in Australia

Closer to home, APL England lost approximately 50 containers overboard off the NSW coast in May 2020 and YM Efficiency lost approximately 80 containers overboard off the coast of Newcastle in 2018 in heavy weather. The APL England had previously lost 36 containers crossing the Australian Bight in 2016. In the case of the APL England incident in May 2020, the Australian Transport Safety Bureau concluded that many of the ship fittings (lashing eyes, lashing bridges and deck structures) were not in good condition.

In the case of the YM Efficiency, the ATSB investigation determined that the forces generated during the sudden, heavy rolling placed excessive stresses on containers stowed aft of the ship’s accommodation. This resulted in the structural failure of containers and components of the lashing system, leading to the loss of containers overboard. The condition of the ship’s lashing equipment was considered not to have contributed to the loss of containers. However, the investigation found that the weights and distribution of containers in the affected bays were such that calculated forces exceeded allowable force limits as defined in the ship’s Cargo Securing Manual (CSM). The investigation also identified that the stowage arrangement was not checked for compliance with the CSM’s calculated lashing force limitations during the cargo planning process ashore.

So, what is the cause of these incidents and why this sudden spike in the North Pacific? Until we receive the incident reports from the relevant authorities (the flag state, classification society, shipping company) on each incident we can only speculate, but I would like to offer some comments.

Is it the weather?

It is well known that when encountering severe weather conditions, it is prudent to drastically reduce the ship’s speed and face the prevailing sea state and wind, where possible, more or less head on. This minimises the effect the state of the sea has on the six degrees of freedom that a ship has (heave, sway, surge, roll, pitch and yaw) and consequently minimises the forces on the vessel and in particular on the containers stowed on deck.

Due to the recent increase in global demand for import containers, particularly in the US, container vessels crossing the Pacific have been loaded to full capacity and scheduling has been tight due to delays in vessel berthing (currently there are approximately 40 container vessels waiting off the port of Los Angeles/Long Beach). Could it be that having a fully loaded vessel along with pressure on masters to keep to tight schedules demanded by their owners, have meant that masters may be reluctant to slow down and/or alter course?

Weight problems?

Another theory is that on account that the vessels are fully loaded, the stack weights limits on deck have been exceeded causing container stacks to collapse in heavy weather. Insufficient lashing and deterioration of lashing and securing equipment (as was the case of the APL England), as well as incorrect declaration (usually under declared) of the weights of the containers by the shippers can all contribute to the container stacks coming apart and collapsing when subjected to the enormous forces experienced in extreme weather conditions.

Container ships are subject to pitching and rolling violently, as well as the phenomenon known as parametric rolling which can cause the ship to roll 30 to 40 degrees. This places enormous strain on the lashings and twist locks of containers, which are sometimes stacked 10 high on deck. Other possible causes include the increased incidence of so-called rogue waves encountered by vessels due to changing weather patterns caused by climate change? Climate change may also be gradually changing the weather patterns across our oceans causing deeper and more frequent, depressions.

I look forward to reading the investigation reports of these incidents when released in due course. In the meantime, it might be prudent for masters to heed the inclement weather conditions they are likely to experience, bearing in mind the limitations and particulars, such as stability (container vessels are usually very stiff which exacerbates the rolling), cargo capacity and deck stowage (a full deck increases the windage in heavy weather) of vessels under their command.

Peter van Duyn is a master mariner and maritime logistics expert, Centre for Supply Chain and Logistics, Deakin University.