4.—(1) An owner or master of a vessel must not keep, let for hire or use the vessel on the waterways unless—
(a)the vessel is registered with the Agency under article 5; and
(b)any requirement imposed by the Agency under article 8 when registering the vessel is complied with.
(2) Paragraph (1) does not apply in relation to a vessel if the vessel is exempted from its provisions by the Agency in accordance with paragraph (3).
(3) The Agency may exempt any vessel or class of vessel from the provisions of paragraph (1) if, having regard to all the circumstances, it considers that the application of those requirements is not justified in the interests of the regulation of the waterways.