The Enforcement Rules of the Ship Registration Law Article 28

The registration of mortgage for a ship during construction shall be recorded in the special register book.In case the registration of the right of mortgage mentioned in the previous paragraph is not made in the port of registry of the ship, the Shipping Administration Authority at the place of construction undertaking such registration shall send a transcript of the special register book to the Shipping Administration Authority at the port of registry after completing the registration.
中文原文 船舶登記法施行細則第28條
建造中船舶為抵押權登記時,應記載於特別登記簿。
前項抵押權,設定登記,如不在船籍港辦理時,則辦理此項登記之建造地航政機關,應於辦理後將特別登記簿謄本抄送船籍港航政主管機關。

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