Tug boats towing vessels, floats, or barges aboard of which there are explosives will display at all times a red flag of at least 16 square feet surface at the masthead. Tug boats without masts will display the flag at least 10 feet above the upper deck. City Code, 1927, art. 15, §69 1950, art. 11, §71 1966, art. 10, §70 1976/83, art. 10, §70 Ord. 13-336