A port board may issue warrants drawn upon any officer designated the custodian of money belonging to or credited to the port. Warrants shall be signed by the treasurer and countersigned by the president of the port or in the absence or inability of the president to act, by the vice president. Warrants shall show upon their face the nature and extent of the obligation satisfied. They may be used in payment of any obligation of the port, including expenses of operation, payment of the principal amount of port bonds at their maturity and in payment of interest or interest coupons of the bonds at the time the interest becomes due and payable. [Amended by 1971 c.728 § 34]