The Law of Ships Article 19
The validity of the Provisional Certificate of Vessel's Nationality (Register) shall not exceed six months for a ship navigating abroad, or three months for a ship navigating within domestic waters. However, for cases with proper reasons, application may be made for renewal to the shipping administration authority at the port of calling or port of registry before the expiry of the certificate, stating the reason. Validity of the renewed certificate shall not exceed one month, and only one renewal is allowed.
中文原文 船舶法第19條
臨時船舶國籍證書之有效期間，在國外航行之船舶不得超過六個月；在國內航行之船舶不得超過三個月。
但有正當理由者，得敘明理由，於證書有效期間屆滿前，向船舶所在地或船籍港航政機關重行申請換發；重行換發證書之有效期間，不得超過一個月，並以一次為限。
但有正當理由者，得敘明理由，於證書有效期間屆滿前，向船舶所在地或船籍港航政機關重行申請換發；重行換發證書之有效期間，不得超過一個月，並以一次為限。