During the 2025 SAFETY4SEA Hamburg Forum, Gerald Lange, Senior Product Manager CVS, Kaleris, shared tips for improving safety for container ships in rough weather. He highlighted the need for better monitoring of ship movements and using that data to help avoid dangerous situations.
Understanding heavy weather at sea
Heavy weather at sea is more than just rough sailing. It represents a complex and serious operational risk, particularly when it comes to containerized cargo. In such conditions, vessels are subjected to powerful and unpredictable forces, and maintaining the integrity of cargo on board becomes a significant challenge.
One key concern in this context is the loss of containers at sea. Although it may seem like a rare occurrence, understanding its causes and exploring how to mitigate the risks is crucial for improving safety and operational standards across the industry.
How many containers are lost at sea?
To put the issue into perspective, about 250 million containers are transported globally each year. An average number of containers lost at sea annually is around 1,300. While this is a small fraction statistically, each loss matters.
Every container lost can have an environmental impact and contribute to reputational damage. A notable example is the MSC Zoe incident in 2019, where containers washed ashore in the UK, creating a public relations problem and drawing attention to the risks of container transport.
Identifying the main causes of container loss
However, the industry has set an ambitious target: to reduce container losses to zero. Recent research efforts, particularly under the TopTier project, have provided a deeper understanding of the causes behind these incidents.
One key finding is that approximately 65% of container loss incidents are linked to a phenomenon called parametric rolling. This is a non-linear dynamic behavior that occurs when there is resonance between a vessel’s stability and the pattern of incoming waves. It leads to extreme rolling motions that exceed design parameters and can quickly escalate into dangerous situations.
The TopTier project also included feedback from over 15,000 seafarers, highlighting several operational concerns. Many crew members reported that loading plans, which define the positioning of containers, are often delivered late while the vessel is in port. This creates pressure and uncertainty for the crew, who are legally responsible for ensuring the vessel’s seaworthiness.
Moreover, once at sea, there is often limited visibility into how weather conditions affect cargo safety. While weather forecasts are available, the direct impact on the vessel’s current load and lashing condition remains unclear. This lack of actionable insight adds to the risk.
The problem of mis-stowed containers
Another significant finding from TopTier involved the accuracy of stowage plans. Measurements taken in ports such as Hamburg and Rotterdam showed that up to 20% of containers were mis-stowed.
In other words, they were not placed according to the final stowage plan. This discrepancy is critical because the vessel’s lashing computer relies on accurate input to assess load conditions. A misaligned stow plan can lead to incorrect safety assessments and increase the risk of container loss.
Fragmented responsibilities in container operations
The issue is further complicated by the fragmented nature of responsibilities among various stakeholders. The stowage plan is often created by a carrier-owned planning center. Terminal operators focus on port efficiency, such as moves per hour, and once the vessel departs, their role ends.
Meanwhile, shipowners, who are most invested in vessel safety, are not always involved in the planning process. The captain, however, is legally responsible for the vessel and must ensure its seaworthiness despite having little control over container placement or the accuracy of the stowage plan. This mismatch between responsibility and authority poses a serious safety risk.
Industry collaboration and data sharing
To address these issues, the industry is beginning to embrace collaborative approaches and technological innovations. One promising direction is improved data sharing between stakeholders.
By bringing together planners, terminals, and vessel operators, as facilitated by the TopTier project, more cohesive and informed decisions can be made to enhance safety. Tools have also been developed to assist shipmasters at sea.
For instance, guidance such as the “Beware of parametric rolling in the following seas” provides recommendations for avoiding following seas, which can contribute to dangerous rolling conditions. Additionally, roll risk estimators use radar plots to help captains adjust speed and course. These are often the only variables under their control once at sea.
Real-time onboard technology as a solution
Technology now plays an essential role in mitigating risks. Advanced systems combine lashing data with three-dimensional sensors to calculate real-time loads on the container securing system. These systems can detect when safety thresholds are exceeded and provide immediate guidance.
For example, if the system indicates that structural limits are being approached, the onboard interface can offer actionable recommendations, such as adjusting speed or course, to return the vessel to safe operating conditions.
Above article has been edited from Gerald Lange’s presentation during the 2025 SAFETY4SEA Hamburg Forum.
Explore more by watching his video presentation here below
The views presented are only those of the authors and do not necessarily reflect those of SAFETY4SEA and are for information sharing and discussion purposes only.
