Commercial vessel (A) In general The term commercial vessel means a vessel (as defined in section 3 of title 1, United States Code) that is engaged in commercial service (as defined in section 2101 of title 46, United States Code). (B) Exclusion The term commercial vessel does not include a recreational vessel. (7) Discharge incidental to the normal operation of a commercial vessel (A) In general The term discharge incidental to the normal operation of a commercial vessel means— (i) a discharge into navigable waters of the United States from a commercial vessel of— (I) (aa) graywater, bilge water, cooling water, oil water separator effluent, anti-fouling hull coating leachate, boiler or economizer blowdown, byproducts from cathodic protection, controllable pitch propeller and thruster hydraulic fluid, distillation and reverse osmosis brine, elevator pit effluent, firemain system effluent, freshwater layup effluent, gas turbine wash water, motor gasoline and compensating effluent, refrigeration and air condensate effluent, seawater piping biofouling prevention substances, boat engine wet exhaust, sonar dome effluent, exhaust gas scrubber washwater, or stern tube packing gland effluent