Conventionally, the rooms and spaces of a ship are either modeled as volumetric entities, or with the aid of bulkheads and decks. According to our knowledge, no simple representation exists where both entities can be modeled independently, and where automated conversion from one view (volumetric) to the other (planes) is possible. This paper introduces a simple yet effective approach, where a ship designer can mix the use of volumes and planes in any fashion. Furthermore, this modeling method is applied in a novel tool to manage ship subdivision constraints. As quite a few numerical constraints are known a priori, they can be defined in a list and assigned to specific subdivision elements. Examples are bulkhead locations or required tank volumes or deck areas. A constraint management tool is developed that evaluates the ship layout design during the design process. The designer will be able to modify or add constraints, and the tool will support the designer by managing these constraints during the design process. If the hull form changes, all submitted rules will be updated according to the new main particulars. If one of the constraints does not comply, an adjustment or alternative can be chosen at that moment and the impact of this change is directly visible. The designer can also ask the tool to provide a ship layout design that complies best with the constraints entered. When the Constraint Management program is used, a feasible ship compartment design can be made in a quick manner and the designer is kept from making errors. This means that a correct ship layout model is available on which probabilistic damage stability calculations and weight estimations can be performed in an early stage. This method has been implemented in a computer program, so actual design examples are discussed.