The provisions of this chapter shall be applicable to the operation of any and all vessels or watercraft in the waters of the city except that they shall not apply in the following cases:

To any authorized emergency vessel or watercraft actually responding to an emergency call or in immediate pursuit of an actual or suspected violator of the law, within the purpose for which such emergency vessel or watercraft has been authorized; provided, that the provisions of this section shall not relieve the operator of an authorized emergency vessel or watercraft of the duty to operate with due regard for the safety of all persons using the waters of the city. (1961 code § 13.09.350.)