(1)Subject to the provisions of this section the provisions of this Act relating to compulsory pilotage shall not apply to tugs, dredgers, sludge-vessels, barges, and other similar craft—
(a)belonging to or hired by a dock, harbour or water authority whilst employed in the exercise of the statutory powers or duties of the authority and navigating within any pilotage district which includes within its limits the whole or any part of the area of the authority; or
(b)belonging to a local authority whilst employed in the exercise of the statutory powers or duties of the authority and navigating within the pilotage district within which the port to which they belong is situated.
(2)Where in any pilotage district any of the classes of craft mentioned in subsection (1) above were at the time of the passing of this Act in practice subject to compulsory pilotage, the pilotage authority may by byelaw provide that any of such classes of craft shall continue to be so subject.
(3)The Secretary of State may by order provide that the provisions of this Act relating to compulsory pilotage shall apply to such of the craft mentioned in subsection (1) above as may be specified in the order.
(4)Until such day as the Secretary of State may by order appoint, subsection (3) above shall be omitted; and different days may be appointed under this subsection for different purposes.