Seafarer's Service Regulations Article 12

Seafarers shall work shifts pursuant to the schedule made while ships are sailing or in berth. Seafarers keeping watch shall not be absent unless they have obtained the director's permission. During shift changes, if the relieving personnel have not yet arrived to take over duty, the seafarer currently keeping watch shall continue to do so and then notify the director or the master if the situation becomes serious.
中文原文 船員服務規則第12條
船舶在航行時或錨泊中船員均應依規定按時輪值,各當值船員,非經主管許可,不得擅離職守。
交值時,在接替者未接替前,仍應繼續工作,並即報告主管處理,如情形嚴重者,則報請船長議處。

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