In the context of the hydrodynamic loading and structural response of thin– walled structures, slamming type of loading makes an essential part on both the local and global level, where it can cause severe damage to the local structural elements and transient vibrations of the hull. In order to define an adequate load calculation methods due to slamming in the preliminary design stage, as well as analysis of the local response of the structure, a direct approach in calculation of hydrodynamic loading is considered using potential flow analysis. A comprehensive insight into the existing calculation methods is evaluated and among them the important group of so called generalized Wagner approach is explained in detail. The generalized Wagner models assume the simplification of free surface boundary conditions while the boundary condition on the wetted surface of the body remains in an original form. The velocity potential is represented by Green’s third identity which is solved numerically using boundary element method. A basic approach of generalized Wagner method is implemented in a form of programming source code to allow a detailed analysis of all its characteristics. The analysis includes solution convergence evaluation and determination of a size of the free surface domain by varying the input parameters of the model (a number and a length of the segments on the wetted part of the body and the free surface). These imperfections in the existing PW methods are partialy removed with a development of an enhanced Generalized Wagner method. In order to achive more accurate pressure distribution on the wetted surface of the body the velocity potential is desingularized. A function of the velocity potential is divided into two separate parts: a regular and a singular one. The singular part is defined by the function which describes a behaviour of the solution close to the contact points. In order to simplify a calculation a new Green’s function of Kelvin’s type is introduced. Using the new approach there is no need for a discretization of the free surface because the boundary condition on that part of the domain is satisfied exactly. Also, a local response of a stiffened panel due to slamming is analysed. As an example a part of a bottom structure of a ship is used. The calculation of the impact loads is performed using the enhanced generalized Wagner method. Then, the pressures are mapped into a structural FEM model using a spatial and temporal interpolation. Due to the rigidity of the local structure, the structural analysis is performed using quasi-static approach neglecting inertial forces. The model is loaded by static impact pressure at several time steps and the response is calculated for each of them separately. Using the FEM results the propagation of significant shear forces along the the stiffened structure is analysed.