## 1 Introduction
The viscoelastic properties of these materials, confined in a less deformable material, contribute in a very significant way to improve the performance of the material in service and dissipate a greater percentage of the energy received on impact, minimizing the damage generated in the material due to the slamming pressure peaks generated during navigation. For this reason, the energy produced in each of the impacts is studied in the laboratory from the perspective of the vertical impact due to drop weight, introducing an energy accumulated in the reproduction of slamming. This added to the microstructural observation, shows significantly the behavior of the damage evolution [9; 10]  
Among the questions pending in previous studies, was the problem of the adhesion of the viscoelastic sheet on the matrix. Through cohesive theory model studies, this concern has been answered for designers, who must consider within their structural calculations that the stress and strain limits do not exceed the adhesion and spread propagation thresholds. The test performed is a modified version of the ISO 11343, a standardized Wedge Peel test method that allows to measure the dynamic resistance of structural adhesives to cleavage at different strain speeds. In the application that is envisaged for this viscoelastic layer in GFRP, designed for protection of the hull of high-speed crafts against slamming impact events, it is important to measure the adhesion strength between the protective layer and the laminate. The test used for this purpose consist of a wedge with an acute shape being driven at a defined velocity into the adhesive bond between both substrates. The wedge induces a bending causing the bond to fracture and adherends to peel apart. The cleavage force and the dynamic resistance to cleavage are consequently calculated from the test force-displacement curve. Because the method is basically grounded in the mechanics of bending beams, it can be analyzed quantitatively using standard fracture mechanics analysis. The absorbed energy is considered as a representative parameter of the behavior of composite materials when subjected to impact loads, and to study the energy behavior during impact,accelerometers with a computer data acquisition system have been used to quantify the energy returned. By observing impact forces and displacement, initial deformation and restitution are analyzed [11; 12]. With the tests presented and the results are expected to answer the question designers if the viscoelastic sheet is ready for use in the construction of new boats GFRP. Energy parameters are also established to define how much the useful life of the planing hull vessel will improve, at the discretion of the manufacturers and users. The present work is an extension of the previous investigations of the authors of this paper, referring to the use of the viscoelastic layer to improve the performance in the GFRP. The tests carried out in previous studies are presented in this article with complements that try to solve the new questions formulated by the designers: is it feasible to install the viscoelastic sheets in the GFRP planing vessel? Are they protected from the cyclical impact of slamming according to the previously resolved benefits and shortcomings? [13; 14] For this reason, the cyclical slamming tests are complemented with the vertical impact due to weight drop to present its benefits from the perspective that the designer wishes to observe. The research aims to show another type of mechanical response of the viscoelastic layer under the perspective of vertical impact, and that the builders have different options for its use. The sheets are inexpensive and easy to cure in the construction of planing hulls. The work has been organized according to the flow of activities shown in Figure 1, in order to present the experimental results from the definition of the experimental method, the slamming pressure levels to be used in vertical impacts, and with this information present discussion in which the comparison of results shown.