ClassNK to Enhance the Safety and Loading Capacity of Container Ships

[By: ClassNK]

ClassNK has released new guidelines for those involved in container shipping, aiming to enhance the efficiency of container stowage while ensuring safety measures  such as preventing cargo collapse. These guidelines apply the latest expertise in weather forecasting, ship motion, and digital twin technologies.

The newly released 'Guidelines for the Safety of Maritime Cargo Based on Weather Forecasts,' 'Guidelines for Anti-Rolling Devices,' and 'Guidelines for Container Stowage and Securing Arrangements (Edition 3.3)' enable safer and higher-capacity container shipping by optimizing stowage based on weather forecasts for short-term voyages, and by taking advantage of the roll reduction effects of anti-rolling devices.

The details of each guideline are as follows: 

'Guidelines for the Safety of Maritime Cargo Based on Weather Forecasts'
Route selection based on metocean information is one of the key factors in the safe transportation of cargo. Although weather forecasts are a valuable source of information when the forecast period is sufficiently short, it is necessary to take their uncertainties into account to ensure safety. However, there have been no specific standards until now, and each company has handled it individually.

By clarifying the correlations between the AIS records accumulated by ClassNK, over one million cases of past metocean data, and actual sea conditions through big data analysis, this guideline specifies new technical requirements for uncertainty qualification of weather forecast values and safety assessments of cargo, and describes corresponding standard evaluation methods. In addition, this guideline also specifies a calculation method for a load correction factor based on weather forecasts for short-term voyages, related to container loading and lashing strength assessments for container carriers.
By applying this guideline, safe and optimized stowage operations can be achieved in short-term voyages based on weather forecasts.

'Guidelines for Anti-Rolling Devices'
Anti-rolling devices such as anti-rolling tanks have been increasingly installed on cargo ships in recent years for the purpose of improving safety, comfort, and work efficiency by reducing ship rolling. With growing concerns about cargo collapse accidents, attention to anti-rolling tanks has increased. While their installation on large merchant ships has started to spread, there have been no common safety standards so far.

This guideline specifies technical and inspection requirements for anti-rolling devices installed on ships, making use of the expertise on ship motions gained during the development of the 'Guidelines for Parametric Roll Countermeasures,' and sets out a method for evaluating the effect of anti-rolling tanks on reducing roll motion. 
By applying this guideline, safe container stowage operations considering the roll reduction effects of anti-rolling devices can be realized.

'Guidelines for Container Stowage and Securing Arrangements' (Revised)
The 'Guidelines for Container Stowage and Securing Arrangements (Edition 3.0),' released in 2023, has contributed to balancing safety and economic efficiency by enabling optimized stowage operations that take into account the effects of routes and seasons, in response to the enlargement of container ships and advances in lashing technology.

With the release of the guidelines on weather forecasts and anti-rolling devices, the related requirements have now been revised to enable container stowage that also reflects these factors.
The guidelines are available for download via "Guidelines" of My Page on ClassNK’s website after registration: https://www.classnk.or.jp/account/en/Rules_Guidance/ssl/guidelines.aspx

ClassNK will continue to contribute to achieving safe and efficient shipping under various operating conditions through the guidelines and other initiatives.