A good ship design is a balanced design, in which the performance is not limited (or outperformed) by one specific characteristic. Today’s state of the art design tools help the designer to make this trade-off, for instance by means of multi-objective optimisation techniques. However these techniques require clear objectives, and underlying calculation approaches should be accurate, otherwise a suboptimal solution is found in the best case (or worse, no solution is found at all). The design objectives are complicated by including real operational conditions, such as ‘off-design’ speed and loading condition, wind, waves, and confined water. In this ‘design for service’, these objectives are often not readily available and calculation approaches are not clearly defined. This paper provides some ideas and guidelines about how to approach such a problem applied to a 120 m cruise vessel.