Unmanned Surface Vehicles (USV) are widely used in recent years in various fields, such as military, leisure, tourism, and rescue. The optimisation of the USV hull design is increasingly needed to achieve higher aero-hydrodynamic performances such as: resistance, propulsive power and seakeeping performances. This work aims to achieve a comparative study of the aero-hydrodynamic performances of the USV hull design between using Computational Fluid Dynamics (CFD) and semi-empirical approaches with Maxsurf. By using CFD methods, two fluids will be considered, water for submerged parts, and air for aerodynamic parts of the USV hull. By using Maxsurf software, different algorithms are provided for estimating the USV hull performances. Both of these tools allow to produce effective optimal designs within a short period of time, especially at the early stage of the design.