Active control of ship roll is necessary for operability of an important number of ships. As such it has been strongly developed in the past twenty years. A way of improving performances is to use and control rudders as well as fins. A MIMO control law synthesis methodology is presented in this paper, which is based on multi-objective optimisation. The optimisation is realised with a genetic algorithm. It is applied to a PID and a H∞ controller, both MIMO. Simulation results with various speeds are given.