The Law of Ships Article 41

A ship acquired abroad which has been measured by the same mode as that of the R.O.C. may be exempted from re-measurement.A ship acquired abroad which has been measured by a different mode from that of the R.O.C. shall be re-measured through an application made in accordance with the relevant regulations. The owner of the ship may apply for issuance of a Provisional Certificate of Vessel's Nationality (Register) before applying for measurement and obtaining the Tonnage Certificate, with the tonnage document issued by the former flag state.
中文原文 船舶法第41條
自國外輸入之船舶,其原丈量程式與中華民國丈量程式相同者,免予重行丈量。
自國外輸入之船舶,其原丈量程式與中華民國丈量程式不同者,仍應依規定申請丈量;船舶所有人於申請丈量、領有噸位證書前,得憑原船籍國之噸位證明文件,先行申請核發臨時船舶國籍證書。

English translation for reference only; the Chinese text prevails. Not legal advice.