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Abstract: A new set of intact stability criteria is under development at IMO with the aim to address the stability failures of a ship in a seaway. These criteria are structured in a three level approach. The first two levels consist of calculations characterized by different levels of accuracy. The third level is named “direct assessment” and typically a numerical tool for hydrodynamics calculations is envisaged for the assessment. However, at present no criteria or procedures have been developed for this third level. In the various scenarios of modern merchant ships, Ro Ro-Passenger vessels represent a very interesting field of investigation for intact stability vulnerability assessment especially for the righting lever variations in waves. For the specific stability failures of parametric roll and pure loss of stability, in the present paper, we apply the 2nd Generation of Intact Stability Criteria to some typical Ro Ro-Passenger ferries and results are presented in terms of computed curves of minimum required GM. We have also carried out a direct assessment of the stability using the “Insufficient Stability Event Index” (ISEI- concept) and compared the obtained GMReq – curves. This comprehensive investigation has the purpose to assess the reliability of the newly proposed criteria as technically consistent and harmonized safety rules. To this aim the investigation domain has been enhanced to the cargo ships field, in particular considering three selected containerships that have suffered serious accidents in a heavy seaway.