Vessels are becoming more and more optimized towards their mission and an increasing amount of systems are considered during this optimization. Most of these considerations occur at an early design stage, where data is scarce and their impact is large. This research aims to aid designers in considering this growing forest of possible system using concept exploration. During this exploration both the mission of the vessel and the wishes of the owner of said vessel (or client) are considered. To do so a methodology is developed, which compares a large set of possible power plant configurations based on fuel consumption, emissions, system mass and volume. To obtain data for these four characteristics the design of each power plant is required. To obtain this the systems inside a power plant have to be designed individually. During the design of these systems several design choices are encountered. These choices are solved using the preferences of the client, which are defined as multi criteria weight factors related to the aforementioned characteristics. And as such create individual systems and from that a power plant configuration, which is optimal according to the client. The entire selection process is demonstrated using three separate cases; a bulk cargo carrier, a harbor tug and a Trailing Hopper Suction Dredger.