How museum ships retain historical value

When does a rebuilt historic ship stop being useful historical evidence?

Historical value depends on surviving original fabric, form, layout, and the extent to which repairs preserve the ship's character instead of remaking it.

Preservation does not require a museum ship to remain untouched. A floating ship needs repairs and replacement components, yet it retains historical value when its outline, internal arrangement, and much of its original fabric survive. HMS Belfast and HMAS Vampire show how necessary maintenance can preserve a vessel's identity. A comprehensive rebuild that changes form and layout moves closer to the Ship of Theseus problem and weakens the ship's value as evidence.