The Enforcement Rules of the Ship Registration Law Article 21

When making a collateral registration for an alteration of registered entry pursuant to Article 24 or 39 of the Ship Registration Law, any alteration of the entry in the part of "Indications of Ship" shall be deleted by drawing a vertical line, and beside it shall the new entry be recorded. The person in charge shall then stamp such alteration with his title chop.
中文原文 船舶登記法施行細則第21條
依船舶登記法第二十四條或第三十九條為附記登記時,登記事項變更,除為附記登記外,有關標示部已經變更之事項,應加劃直線註銷之,於其旁記載相關變更事項,並加蓋主辦人員職名章。

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