This paper describes the research in identifying the key data elements that are indicative of the material state of a naval vessel. Naval vessels are long lived complex artefacts, containing in excess of 100 integrated “hard” systems. The systems may be configured to provide a variety of prescribed capabilities and associated command objective. However, the “hard” systems will not fully integrate or function in a cohesive manner without the interaction of “soft” socio-technical systems (e.g. maintenance teams, operators); the two are interdependent and reliant. The In-Service phase will contribute 70% of the artefact’s through-life costs and may comprise an operating period of more than 25 years. The data generated and utilised within each mode will reflect the operational and technical requirements of the numerous stakeholders and the functional state of the vessel.