This work addresses one of the most common problems for mobile robotics (autonomous navigation) but is applied to the dynamical model of a catamaran of small dimensions for monitoring and data acquisition applications. In this work, we present the study of the dynamics of a USV (Unmanned Surface Vehicle) under the presence of two simulated environmental perturbations: marine induced waves and currents. The mathematical model of the vehicle is studied and the equations that describe the behavior of environmental perturbations are also described. A numerical simulation of the model considering the effects of these perturbations is carried out in three degrees of freedom. Also, a strategy of robust control-based Sliding Mode Control (SMC) is developed for counteracting the effects of the perturbations over the trajectory of the USV.