Mo. Rev. Stat. § 306.122: Motorboat or vessel operator, minimum age, exceptions, penalty.

No person under fourteen years of age shall operate any motorboat or vessel upon the waters of this state unless such person is under the direct on-board supervision of a parent, guardian or other person sixteen years of age or older, or unless the motorboat is moored. No person shall authorize or knowingly permit a motorboat owned by such person or under the person's control to be operated on the waters of this state in violation of this section, nor shall a parent or guardian authorize or knowingly permit such a child, under fourteen years of age, to operate a motorboat in violation of this section.