Securing container safety


The size of deep sea container ships has increased dramatically over the past decades. The loss of containers and their impact on the marine and coastal environments raised public and politic concerns on the safety and environmental impact of modern container ships. Authorities and industry are urged to evaluate container securing and improve regulations and practices to avoid such loss of containers at sea. The Joint Industry Project TopTier is initiated to address these topics with active participation of major stakeholders.
The primary objectives of the TopTier JIP are to identify and recommend improvements for transport, stowing and securing containers and related matters, and provide the technical understanding that is needed for safe designs and innovations in the future. TopTier addresses these objectives together with a wide consortium of stakeholders from both the shipping industry and authorities responsible for overall safety to ensure the required expertise and to achieve leverage for acceptance of findings.

The TopTier project started in May 2021. By mid 2022, the project is supported by 40 participants including 3 national authorities, 10 major carriers, 7 class societies and 5 lashing manufacturers.

Phase 1 reviewed current practice and incidents and identified gaps. Several succesfull meetings took place and three reports were submitted for review. This phase was concluded with three early deliverables to alert mariners to the particular phenomena of parametric roll in following seas conditions. More information and downloads

Mid 2022, work has shifted to phase 2 of the project. Six working groups are undertaking detailed technical research and investigations. These working groups contribute to the overall project goal with targets that are complementary. The outputs will be combined into practical safety improvements during phase3 of the project.


Contact person photo

Jos Koning

Senior Project Manager

TopTier | work in progress
Project participants


A series of incidents with exceptional container losses occurred during the winter season 2020-2021. Initial results show that parametric rolling in following seas was especially hazardous. The TopTier JIP took initiative to distribute a Notice to Mariners. This information gives guidance to crew and operational staff of container ships on how to plan, recognize and act to prevent parametric rolling in following seas.
  • Read the Notice to Mariners for details and a flowchart
  • Watch the video to learn about parametric roll in following seas
  • Use to calculation tool for explicit guidance
Parametric roll in following seas
In this video we show how to recognise and prevent parametric roll in following seas
Parametric roll in head seas
In this video we show how to recognise and prevent parametric roll in head seas
Resonant roll in stern (quartering) seas
In this video we show how to recognise and prevent resonant roll in stern (quartering) seas

TOPTIER JIP information


Container transport aims for maximized efficiency operations inside the rules and boundaries defined for safety by (flag state) administrations and class. Unsafe situations occur if these boundaries are not respected, are unclear, or are too low. Recent incidents with modern large vessels operated by major shipping companies suggest that the current approach does not sufficiently cover the relevant aspects for the newest classes of ultra large container ships. A better understanding of the operations, the hazards and the working mechanisms is necessary. Updates to rules, requirements and operational procedures should be recommended and implemented from top down levels in order to apply for all involved players.

The Lashing@Sea Joint Industry Project (MARIN 2006-2009) investigated the container transport with a wide consortium from shipping industry and flag state administrations. Now ten years later, vessel dimensions have increased from 10 kTEU to 24 kTEU. A series of recent incidents suggest that scale effects and increased economic pressure are pushing the container operations beyond safe boundaries. The present TopTier project is a follow-up of the Lashing@Sea JIP to address safety concerns in container transport with a wide consortium to aim for a safer and a level playing field.


The primary objectives are to restore fidelity in the safety of container transport with the present fleet and provide the technical understanding that is needed for safe designs and innovations for the future. TopTier addresses these objectives with a wide consortium of stakeholders to ensure the required expertise and to achieve leverage for acceptance of end findings. Industry wide impact of findings and recommendations will be sought by cooperating with high-level bodies as WSC, ITF, IMO, IACS, ISO and ILO through submitting results and requesting follow-up actions.


The project approach will be around three underlying ideas:
  • Accurate technical understanding and representation of ship motions and cargo securing mechanics as used in design, plan approval and operational securing calculations;
  • Maximize awareness and ability of the crew to perform their operational role to keep ship motions within the (hidden) limits as used in securing calculations;
  • Reduce uncertainties in the computer representation of the real situation on the deck;
  • Anchoring minimal requirements to above mentioned factors in the regulatory framework for container cargo securing.
Technical issues are the aspects that are presently not yet included in the securing procedures / practices. The aim is to understand, demonstrate and recommend on how to deal with effects of extreme motions, high GM, hull girder flexibility, flexibility of containers and lashing gear components, high stack dynamics, row interactions, multi row resonance, non-linear cargo securing loads, design motion envelope statistics and realistic operating loads for containers and securing gear.

Operational aspects aim to increase awareness of actual loads in relation to the design values used in cargo calculations, probability indicators for extreme events and mitigating actions. This will be based on experience developed over the past two decades, related to parametric and synchronous roll, dynamic loss of stability, and the findings of the technical investigations in the project.

The process aspects will address options and infrastructure requirements to improve tracking of container and corner casting condition, state of maintenance of the securing arrangement, and the weight, content and stuffing of the containers themselves.

The last but not least challenge is to propose how minimal standards to these complex approached can be practically included in the existing regulatory framework by IMO, flagstate authorities and class in order to ensure a level safe playing field including the world outside the group of participants.

SCOPE OF WORK & Activities

Presently considered scope of work and activities include:
  • Review of current practice, incident review and gap analysis;
  • On board measurements for long term ship motions, hull girder flexibility and related accelerations. Output statistics to be shared;
  • Model tests and numerical studies aimed at “off design” conditions and options how to avoid them;
  • Desk studies and model test program on an earth quake simulator to understand high tier and multi row dynamics;
  • In-service measurements on multi-stack-container response at selected transits;
  • Securing load indicator based on measured response and cargo securing calculations;
  • Threat indicator for extreme motions based on measured response;
  • Realistic design ratings for container and securing gear;
  • Stack optimisation for minimal probability of row resonance;
  • Technology and required infrastructure for identification and tracking of condition and wear of container corner castings (which is essential for high stack and FAT performance);
  • Review of regulatory requirements to container securing guidelines en operating practices.


The project consortium relies on cooperation, expertise and support from vessel and container operators, authorities and stakeholders in authorities and the industry both at sea and shore side.


The direct findings in the project will be shared with the participants. The outcome of the project will be further brought to the attention of authorities as IMO, ILO and IACS to aim for top-down implementation for a continued level and safe playing field both at sea and on shore.


The TopTier JIP started in May 2021 and will run for a period of three years. Project steering group meetings will be held twice per year where intermediate results will be presented and discussed.
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