(a) In cities having a population of more than 500,000 inhabitants, whenever an abandoned, lost, stolen or unclaimed watercraft or other watercraft remains unclaimed by the registered owner, lienholder or other legally entitled person for a period of 15 days after notice has been given as provided in Sections 3C-5 and 3C-6, the watercraft may be disposed of as provided in the “Municipal purchasing act for cities of 500,000 or more population”.
     (b) Except as provided in subsection (a), when an abandoned, lost, stolen or unclaimed watercraft 7 years of age or newer remains unclaimed by the registered owner, lienholder or other person legally entitled to its possession for a period of 30 days after notice has been given as provided in Sections 3C-5 and 3C-6, the law enforcement agency or towing service having possession of the watercraft shall cause it to be sold at public sale to the highest bidder. Notice of the time and place of the sale shall be posted in a conspicuous place for at least 10 days prior to the sale, on the premises where the watercraft has been impounded. At least 10 days prior to the sale, the law enforcement agency where the watercraft is impounded, or the towing service where the watercraft is impounded, shall cause a notice of the time and place of the sale to be sent by certified mail to the registered owner, lienholder and other persons known by the law enforcement agency or towing service to be legally entitled to the possession of the watercraft. Such notice shall contain a complete description of the watercraft to be sold and what steps must be taken by any legally entitled person to reclaim the watercraft. In those instances where the certified notification specified in Sections 3C-5 and 3C-6 has been returned by the postal authorities to the law enforcement agency or towing service due to the addressee having moved, or being unknown at the address obtained from the registration records of this State, the sending of a second certified notice will not be required.