How to reconstruct naval history when records are missing

How can historians reconstruct naval developments when the central archival sources are missing?

Combine personal papers and interviews with photographs, engineering evidence, and independent cross-checks instead of relying on one surviving account.

Missing central records make personal archives and interviews especially useful. People who did not work directly on a project can still identify participants or remember who was away at a relevant time. Diaries and private papers provide other leads. If documentary searches fail, photographs can support forensic engineering and approximate measurements of a ship or system. Agreement between those measurements and published dimensions increases confidence without making the estimates exact. The method depends on checking information instead of accepting an account because it survives.