Understanding the assumptions in the class rules is an essential not only for compliance with IMO GBS (Goal-Based Standards) but also for developing safer and robust design of vessels. Without a understanding of the rules, they can become a black box, potentially leading to misinterpretations.

In this regard, IACS has consistently provided the industry with comprehensive information, including TB (Technical Background) and CA (Consequence Assessment) results, pertinent to IACS Resolutions, including the CSR. Moreover, IACS Rec. 34 Rev.2 and subsequent revisions to the current CSR are being developed with the aim of helping the industry sufficiently understand the background of the rules from this perspective. This is achieved by incorporating feedback through extensive engagements with the industry during their development process, and approach anticipated to assist the industry in the broad comprehension and effective application of the class rules.

Balancing structural safety and GHG reduction isn’t about sacrificing one for the other. It’s about achieving both through robust design, advanced technology, and a holistic understanding of a ship’s lifecycle and operational environment. In this perspective, the revision in IACS Rec. 34 Rev.2 and subsequent revisions to the current CSR capitalise on advancement in technology and data collection methods, providing more comprehensive and accurate wave data, and utilising factors such as ship speed, heading, and ships’ positions. These enhancements represent a significant improvement to modelling real-world conditions, supporting the ongoing evolution of ship design and safety measures, corresponding to new challenges, such as GHG reduction.

The revised CSR based on Rec.34 Rev.2 will result in higher hull girder wave loads than current CSR and allows for greater preparedness in meeting the demands of changes to environmental standards, including provisions for more environmentally friendly ship designs, adding new clean technology such as wind propulsions or air lubrication, and adapting to new fuel types.

Any scantling reduction or increase due to the increased hull girder load is a direct result of the new loads introduced by the revision of Rec.34 Rev.2. IACS is confident that these new wave loads are more accurate and possess strong technical background, replacing numerous previously used empirical and operational factors. CSR changes would not necessarily lead to increased steel requirements. More complex calculations for general ship design based on state-of-the-art computational tools will give a much clearer and realistic indication of how the design can be improved.

Through a review of survey experiences with current CSR vessels and an investigation of damage cases during operation, IACS will strive to provide more rational structural requirements that strike a balance, without compromising safety, by conducting CA (Consequence Assessment) for bulk carriers and oil tankers of various sizes.

Moreover, CSR revisions are made with all stakeholders in mind, and as part of a truly collaborative process. Revisions to CSR are subject to extensive scrutiny by all stakeholders (including, but not limited to an external advisory group (EAG), IACS members’ technical committees, and wider industry consultation).

Rule criteria given in the current CSR, except for hull girder ultimate strength will be fundamentally kept unchanged, so there won’t be a significant difference in applying the revisions in the CSR to novel design of the ship.

Furthermore, IACS has developed and provided “Rec 165 – Recommendation for assessing design instances based on application of alternative methods in the hull structural design of CSR ships – Rev.1 Jan 2022 Clean” for novel or alternative designs.

IACS brings together member societies to harmonize technical standards, such as the Common Structural Rules (CSR). However, since each IACS member operates independently – using its own approval software and maintaining individual procedures – IACS is dedicated to continuously developing and enhancing IACS resolutions, including CSR. Further, in accordance with IACS Internal Guidelines, IACS regularly cross-checks to ensure CSR is properly implemented in the software of each IACS member such that consistent results are obtained. These efforts ensure that our clients benefit from clearer, more unified standards, making their work more effective and efficient across all IACS member societies.