Ships are in general designed to first meet their contract speed, which is most times their trial speed. The ship design efforts are dominated by the focus to attain this trial speed. The resulting hull lines design philosophy will most likely not result into the most full efficient design in service conditions. Increasing fuel costs and low freight rates drive the need to design ships for their service conditions. It's operational draughts and added resistance due to waves that should be the key drivers for a successful modern ship design. The last years MARIN has tested and expanded its tools and capacities to support hull form design for minimal fuel consumption in everyday use, minimizing SOx and NOx emissions. Tools suchs as viscous flow calculations in an explorer mode, calculating numerous hull form variations overnight in order to maximize the performance of the vessel, and voyage simulations to determine true service margins are essential when designing a ship.