Systems can be seen simply as collections of resources directed towards defined functions. A ship is a self-contained system that can draw on few additional external sources when at sea. The analysis of the system policy yields very different results according to the purpose of the ship, whether it is for trade or for war. The former generates an inflow of earnings that the latter does not. The maritime architect has to address a number of boundaries, including time, geographic, social, ethnic, physical, organisational, industrial, economic and political. There is also the shore-based investment in compatible cargo transport and handling systems. A process model of ship design becomes a spiral configuration of a decision tree.