Ship plans can hide important material grades

Warships contained many protected tubes, bulkheads, and structural elements whose material mattered even when they were not part of the main belt. An inspection of HMCS Haida compared physical plates with drawings and suggested that a plan can identify the general steel type while concealing differences in grade. Constructor and shipyard correspondence once carried those practical choices, but much of it did not survive. Preserved American ships therefore permit stronger material comparisons than vanished German or Japanese vessels that can be known only through incomplete records. A plan resembles a lecturer's bullet-point notes: it records what the designer needed on paper, rather than every piece of knowledge applied during construction.