In the last years, the issue of renewable energies has been taking on a great importance. There are many forms of renewable energy, among these, wave energy has a great im-portance thanks to his great potential. The purpose of this thesis is to model a floating wave energy converter using the U-Tank technology and also, to define the gross power produced in different marine conditions (regular and irregular waves). The system consists of a floater with an interior U-Tank partially filled with water. The device is moored at the seabed with a mooring system, the floater is designed to be multi-directional; therefore, the device is able to align itself with the incoming wave direction.