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. Taking into account the variations of the environment is a means of improving performances. The ship behaviour is modeled as a MIMO LPV system; a methodology is presented which leads to a gain-scheduled control law. Synthesis is based on multi-objective optimisation and polytopic representation of the standard system, which depends on ship speed and on a stabilisation quality factor. Simulation results are given.