Objectives  This paper selects the U or V degree of ships' stems as the research target for identifying its influence on parametric rolling vulnerability.

  Methods  Three kinds of ships were chosen as the parent ships: a container ship, fishing vessel and fishery administration ship. Three series of ships were generated by changing the U or V degree of these parent ships' stems using the free-form deformation method. Each series contained five newly created ships for a total of 15 new ships. The parametric rolling vulnerability of the ships was assessed and the rule of the influence of the U or V degree of the stem on vulnerability to parametric rolling was obtained from the assessment results.

  Results  The assessment results show that changing the form of the stem from a V section to a U section has an advantageous impact on vulnerability to parametric rolling.

  Conclusions  The research in this paper provides a technical basis for the application of parametric rolling vulnerability criterion in China, and can provide valuable references for hull form design.