A vessel shall not be required to be numbered under this article if it is: (1) A vessel operating under valid temporary certificate or number; (2) Already covered by a number in full force and effect which has been awarded to it pursuant to federal law or a federally approved numbering system of another state; provided, that such vessel shall not have been within this state for a period in excess of 90 consecutive days; (3) A vessel under registry from a country other than the United States temporarily using the waters of this state; (4) A vessel owned by the United States, or a state, county or municipality; (5) A ship’s lifeboat; or (6) A vessel not propelled by machinery, except sail boats and boats for hire. (Acts 1959, No. 576, p. 1442, §18.)