Traditional-ship classification (T-classing) provides culturally historically valuable ships with national certificates and the possibility to sail in international waters.

Older ships still in use need to have their seaworthiness maintained. This often requires special measures to protect the historical features of the vessel.

One measure is traditional-ship classification (T-classing). An application for T-classing is sent to the National Maritime Museums who attaches a statement concerning the cultural-historical value of the vessel. The application is then sent on to the Swedish Transport Agency who decide in the matter.