Except as provided in 33 CFR §173.13 and 33 CFR §173.17 as amended, a person may not use a vessel unless it has on board: A valid certificate of number or temporary certificate for that vessel issued by the issuing authority in the state in which the vessel is principally used; or For the vessel described in §B of this regulation, a copy of the lease or rental agreement, signed by the owner or the owner's authorized representative and by the person leasing or renting the vessel, that contains at least: The vessel number that appears on the certificate of number; and The period of time for which the vessel is leased or rented. The certificate of number for a vessel less than 26 feet in length and leased or rented to another for the latter's noncommercial use of less than 7 days may be retained on shore by the vessel's owner or the owner's representative at the place from which the vessel departs or returns to the possession of the owner or the owner's representative.