No steamer or motor vessel shall travel at a greater speed than six miles per hour, and between sunset and sunrise the speed shall not exceed three miles an hour. The speed shall be reduced to three miles an hour during the day and two miles an hour between sunset and sunrise when passing round a bend, or when approaching a lock or other navigation works. Every steamer or motor vessel shall be furnished with an efficient whistle or hooter and shall whistle or hoot when approaching a bend or a lock. Steamers and motor vessels shall be warped or poled into or out of locks and shall not use their propellers or paddle wheels until quite clear of the lock.