In order to minimize ship type changes and meet the new requirements of SOLAS 2020 for the damaged stability of passenger ships, starting with the layout optimization design of large cruise ships, the ideas and key design factors regarding the improvement of attained subdivision index A (hereinafter referred to as index A) in damaged stability are deeply explored.

Taking a large cruise ship as an example, this paper obtains the key design factors affecting index A through the calculation, analysis and comparison of the influence of different detailed design schemes for index A, as well as the analysis of the SOLAS 2020 requirements.

The index A of a ship can be improved by increasing the reserve buoyancy, adding cross-flooding devices and openings on class-A fire resistant bulkheads, and controlling the relevant design layout according to safety zones and flood waterlines.

This study shows that the index A of cruise ships can be improved to a certain extent by considering the refined design and layout optimization in damaged stability calculation, thereby limiting the optimization of the main dimensions of the cruise ship to within the minimum range.