The topic of this work is the numerical simulation of a problem of interest in the field of offshore technology, namely the inviscid flow around four free–surface piercing cylinders in waves. Three different angles of the incoming wave front are considered in order to investigate the variation of the resulting global and local loads on the four bodies. The rotation of the cylinders configuration with respect to the wave front has been made easy and efficient by the use of a chimera method for the generation of the computational mesh. The free–surface has been simulated by an one–phase level set approach.