On all waterways adjacent to Residence, Commercial or Manufacturing Districts and within view from an arterial highway, a non-conforming advertising sign may be continued for one year after July 23, 1964, if already in operation on April 15, 1964; provided that after the expiration of this period such non-conforming advertising sign shall terminate.

For the purposes of this Section, an advertising sign is a sign that directs attention to a profession, business, commodity, service or entertainment conducted, sold or offered elsewhere than upon the premises of the vessel and is not accessory to a use on such vessel.