This contribution addresses the numerical simulation of parameterized hydroelastic vibrations of an elastic tank partially filled with an inviscid and incompressible liquid with a free surface. The analysis accounts for geometrically nonlinear equilibrium configurations induced by prestressing effects arising from the hydrostatic pressure associated with the liquid weight [1, 2]. The liquid height is considered as the governing parameter. The computational framework is based on a geometrically nonlinear formulation in which the hydrostatic pressure acting on the fluid–structure interface is modeled as a non-uniform follower load depending on the liquid height. Starting from an empty reference configuration, the structure is progressively filled, and a sequence of prestressed equilibrium states is computed. At each configuration, hydroelastic vibrations are evaluated using prestressed dry modes defined on the reference configuration, enabling an efficient prediction of the dynamic response for varying filling and emptying levels. The proposed approach requires, at each parameter value, the evaluation of reduced added-mass and reduced tangent-stiffness operators. Since the dimension of these operators depends on the number of retained modes, an original Proper Orthogonal Decomposition is applied directly to the operators rather than to the solution fields. This strategy enables the reconstruction of the parameterized hydroelastic model using a limited amount of data [3]. The methodology is validated through comparisons with experimental results available in the literature [4], demonstrating its accuracy and efficiency for the analysis of hydroelastic vibrations in fluid-filled structures. [1] Hoareau C., Deü J.-F., Nonlinear equilibrium of partially liquid-filled tanks: A finite element/levelset method to handle hydrostatic follower forces, IJNLM, Vol. 113, pp. 112–127, 2019. [2] Narayanan N.K., Wüchner R., Degroote J., Monolithic and partitioned approaches to determine static deformation of membrane structures due to ponding, C&S, Vol. 244, 106419, 2021. [3] Hoareau C., Deü J.-F., Ohayon R., Construction of reduced order operators for hydroelastic vibrations of prestressed liquid–structure systems using separated parameters decomposition, CMAME, Vol. 402, 115406, 2022. [4] Chiba M., Nonlinear hydroelastic vibration of a cylindrical tank with an elastic bottom containing liquid. Part I: Experiment, JFS, Vol. 6, pp. 181–206, 1992.