Mikasa's unusual preservation under the Washington Naval Treaty

Should Mikasa count as a historic ship despite how much of her original fabric was lost or altered?

Under the material threshold described, probably not: historic-ship status would usually require roughly eighty percent of the original components in their original order, while Mikasa is estimated at about sixty percent. Her value as a naval-heritage site is a separate question.

The strict question is how much of Mikasa's original material remains in its original arrangement. A tentative threshold of roughly eighty percent is given for historic-ship status, while Mikasa is estimated at about sixty percent. Her losses are linked to an explosion and to the way she was preserved under the Washington Naval Treaty. The concrete encasement is judged unnecessarily harsh because this pre-dreadnought posed no credible threat to post-First World War dreadnoughts or cruisers, and perhaps not even to destroyers. The result is an altered vessel whose material authenticity is limited by that preservation history. She nevertheless survives as a public site for Japanese naval heritage.