Regulations for Issuing Certificate of Vessel's Nationality Article 5

Upon receiving the Certificate of Vessel's Nationality, the originally issued Certificate shall be surrendered to the shipping administration authority for cancellation. However, in case of failure to surrender in time due to some extraordinary accident, a 1-month grace may be granted if a statement of reason is furnished and verified. Failure to do so within the specified time limit without any proper reason may render the shipping administration authority to cancel the registration at its own discretion, and publicly announce on the shipping administration authority's bulletin and web site.
中文原文 船舶國籍證書核發規則第5條
船舶所有人於領得換發之國籍證書時,應將舊有證書繳由航政機關註銷。
但因特殊事故未能即時繳銷者,得申敘事由於一個月內繳銷之。
逾期未繳銷者,由航政機關逕行註銷其證書,並於航政機關公告處所及網站公告之。

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