It shall be unlawful to operate any motorboat, except a personal watercraft, at a speed greater than the slowest possible speed required to maintain steerage and headway when within 50 feet or less of docks, piers, boathouses, boat ramps, or a person in the water, unless such person in the water (i) is being towed by the motorboat or (ii) is accompanying the motorboat, provided that such motorboat is propelled by an inboard motor or a means of propulsion that is below the water line and forward of (a) the transom or (b) an integrated swim platform.