No person in charge of any propeller, tug or steamboat shall blow her whistle or cause the same to be blown, while occupying the draw of any bridge in the City, or within one hundred fifty (150) feet thereof, unless the same is blown by a steamer, propeller or tug lying at a dock as a signal for the opening of the next nearest bridge, or when required by Federal laws or regulations. However, this section shall not apply to cases of fire or distress.