Ala. Code § 33-2-186

The docks facilities revenue bonds and refunding bonds shall not be general obligations of the department but shall be payable solely out of docks facilities revenues. As security for the payment of the principal of, premium, if any, and interest on the docks facilities revenue bonds and refunding bonds issued by it under this article, the department is hereby authorized and empowered to pledge for payment of the said principal, premium, if any, and interest all or any part of the docks facilities revenues. All contracts made and all docks facilities revenue bonds and refunding bonds issued by the department pursuant to the provisions of this article shall be solely and exclusively obligations of the department and shall not be an obligation or debt of the state. The docks facilities revenue bonds and refunding bonds, except while registered, shall be construed to be negotiable instruments although payable solely from a specified source as herein provided.