All docks and wharves shall be equipped with fender logs not less than 24 inches in diameter at the smallest part.  It is unlawful for any vessel, steamboat, or other watercraft, except boats or watercraft operating exclusively on the Willamette or Columbia rivers, to lie alongside of any wharf or dock in the City, unless such vessel, steamboat or other watercraft shall be fended off from said wharf or dock so that no part of such vessel, steamboat, or other watercraft shall be nearer than 2 feet from the nearest point of the wharf or dock by a floating fender, log or spar of sufficient strength to maintain the distance of 2 feet.  Each spar and each chain, Hawser, rope or line of any kind, extending from any vessel, steamboat, or watercraft, to the wharf or dock, shall be equipped with and have properly and securely attached thereto a rat shield or guard of such design, and in such manner, as shall be approved by the Health Officer.