## 5 Conclusions  
The Second-Generation Intact Stability Criteria opened doors for operation-based intact stability assessment, and the operational measure is the initial step toward the design of a performance-based dynamic stability assessment. The SGISC recommends the standard wave scatter table (WST) for the environmental data, an indefinite requirement for a simplified assessment pathway, which provides the probability of wave occurrence. Further, simplified operation measures are possible through operational limitation and guidance. However, the current IMO SGISC guideline allows unrestricted operation once successfully assessed by the standard WST. Such unchecked operational ability of ships needs to be verified for different sea areas for ships to operate unrestricted. To improve the assessment mechanism introduced by the SGISC, the differences in hindcast regional and seasonal WSTs are investigated and compared with the standard WST. This research aimed to identify the difference in the hindcast WST and standard WST in the application of the SGISC. The Rayleigh pdf shape factor was utilised for comparison of the hindcast seasonal and regional WSTs with the corresponding IMO recommended standard WST. In this study, sea areas 8, 9, 15 and 16 were selected for the comparison study, as the sea areas selected together form the standard WST. The result shows the Rayleigh shape factor variation by almost 30% for seasons 2 and 4, with the maximum variation of 49% for sea area 9 wind sea in season 4 when compared with the standard WST. It clearly indicates the difference in the probability of wave occurrence for the same sea area in the different seasons. This variation will contribute to the estimated operating time of the ship on each wave. Thus, by the use of hindcast data, the actual representation of the sea area is achieved for smaller regions and time frames for the estimation of ship stability. The difference in operational time on each wave contributes significantly to safety estimation not just for vulnerability criteria but also for direct stability assessments. In a case study, the WST variation was further analysed by estimating operational limitations for the C11 container ship. The case study aims to investigate the difference in operational limitation estimate when using the hindcast WST over the standard WST and verifying the need for hindcast data in the SGISC application. The paper compares the results of VCI excessive acceleration for a C11 container ship. The results match the case study provided in the explanatory notes for the standard WST; furthermore, the ship's excessive acceleration varies for each region and season, and the estimates are higher in season 4 compared to the standard WST. The outcome achieved using the standard WST varies largely and shows higher excessive acceleration for the region within the sea areas 8, 9, 15 and 16, especially in season 4. It is therefore recommended to evaluate the acceptance of ship operation for all seas and seasons by individual seasonal and sea area data instead of using the standard WST, and the estimation of ship stability using the standard WST is to be considered an operational limitation for sea areas 8, 9, 15 and 16. In conclusion, the study recommends the use of regional and seasonal hindcast data for vulnerability criteria assessment, and the unrestricted ship operation with successful validation using the standard WST requires re-evaluation to improve the safety of operations. In fact, the identified challenge for using WSTs is not limited to vulnerability criteria alone, but the effect is more significant in direct stability assessment as the operational time factor changes with the probability of occurrence change for each wave. The other important factor is the wave period variation in each sea area. This will affect the estimation of parametric rolling using vulnerability criteria. The opportunity for further research is extensive, as this paper identified the limits of the standard WST.