The Seafarer Act Article 75-3

Yachts and power-driven small ships may sail only when they are manned with qualified masters and assistants. Provided that no assistant is needed in a ship with a gross tonnage below five or ship with a gross tonnage is five or above but with a passenger quota under 12.
中文原文 船員法第75-3條
遊艇及動力小船應配置合格駕駛及助手,始得航行。
但船舶總噸位未滿五或總噸位五以上之乘客定額未滿十二人者,得不設助手。

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