A key building block of digital twin solutions is a virtual counterpart for an asset that can be coupled to the asset throughout its lifecycle – predicting an asset’s potential performance at design and providing insight into operation during service. This paper presents the development of human digital twins that integrate human factors into conventional ship design procedures, particularly focussing on seakeeping performance assessments. A novel method for incorporating human-centric performance criteria in seakeeping analyses is proposed and initial validation thereof is detailed. Human digital twins are seen to provide a platform for informing the ship design process using data captured during vessel operation.