(1) If money due to a port authority is not paid in full by the time when it is due, or such time after then as the port authority may allow, interest on the amount outstanding at the rate prescribed by regulations is to be paid to the port authority.

(2) Interest under subsection (1) may be recovered by a port authority in the same way as the money due to it may be recovered.

(3) Unless the context requires otherwise, a reference in this Act to port charges is to be taken as including a reference to interest under subsection (1) payable on those port charges if they are overdue.

(4) Subsection (1) does not apply in respect of money due under a written agreement where the rate of interest to be paid is specified in the agreement.