Exemption from numbering provisions of this chapter

A motorboat may not be required to be numbered under this chapter if it is: 1. Already covered by a number, in full force and effect, awarded it pursuant to federal law or a federally approved numbering system of another state, provided such motorboat has not been within this state for more than ninety consecutive days. 2. A motorboat from a foreign country temporarily using the waters of this state. 3. A motorboat owned by the United States, a state, or a subdivision thereof. 4. A ship's lifeboat.