4.—(1) A vessel to which this Part applies shall carry in command of the vessel a person who is qualified for the purpose in accordance with paragraph (2) below.
(2) For the purposes of paragraph (1) above a person is qualified if—
(a)he is the holder of a certificate (in these Regulations referred to as a “licence”) issued by the Secretary of State under this Part stating that he is qualified to have command of such a vessel;
(b)the licence is in force and is of a grade appropriate in respect both of the waters in which the vessel is being navigated and the number of passenges carried; and
(c)the vessel is in an area specified in the licence as one in which a vessel may be navigated under the command of the holder.