This paper presents a fuzzy approach for the MAritime RISk Assessment (MARISA) applied to safety at sea. The aim of this work is to define automatically an individual ship risk factor which could be used in a decision making system. To achieve this purpose, a modular and hierarchical structure using fuzzy logic has been developed. It allows us to obtain a fuzzy risk factor (FRF) composed of a static risk factor (SRF) and a dynamic risk factor (DRF). The static risk factor assessment takes into account several static data relative to the ship (age, flag, gross tonnage, number of companies, duration of detention and type). The dynamic risk factor is evaluated by considering the meteorological conditions (sea state, wind speed and visibility) and the moment of the day. Moreover, the MARISA graphic interface developed with the Labview software is presented. This interface allows several simulations to be carried out to validate the fuzzy method proposed. Simulation results are presented.