Me. Rev. Stat. tit. 12, § 12854

A guide carrying passengers for hire must be certified in the area of watercraft safety. A guide who has been certified in watercraft safety through the guide license examination process is authorized, without further licensing requirements, to operate a motorboat carrying passengers for hire pursuant to section 13063, subsection 2. A guide license issued to a guide who has been certified in watercraft safety must clearly indicate that the licensee is authorized to operate a motorboat carrying passengers for hire.