Requirements defined by shipping firms play a role as the communication interface of product information between these firms and shipbuilders, and the product design is optimized based on the requirements. Ship service life is about 30 years, during which original requirements may lose some relevance. In this paper we explore the introduction of uncertainty and flexibility into requirements so that ships are designed optimally not only for a single given technical condition but for a range of possible operational scenarios, including shifts in the economic environment for shipping firms.