20.—(1) The owner and the master of a United Kingdom ship must ensure that the condition of the ship and its equipment are maintained to conform with the provisions of Part 3 (equipment), so as to ensure that the ship in all respects remains fit to proceed to sea without presenting an unreasonable threat of harm to the marine environment.
(2) The owner and the master of a United Kingdom ship must ensure that after any survey of the ship required by this Part has been completed, no change, except by way of direct replacement, is made to the structure, equipment, systems, fittings, arrangements or material of that ship without the approval of—
(a)the Certifying Authority who appointed the surveyor to carry out the survey; or
(b)the Secretary of State, where the Sewage Certificate was issued by a Contracting State other than the United Kingdom following a request made pursuant to regulation 15 (issue of a Sewage Certificate by another Contracting State in respect of United Kingdom ships),
as the case may be.
(3) Whenever—
(a)an accident occurs to a United Kingdom ship, or
(b)a defect is discovered in a United Kingdom ship,
which substantially affects the integrity of the ship or the efficiency or completeness of the equipment of the ship required under Part 3 (equipment), the owner and the master of the ship must comply with the requirements of paragraph (4).
(4) The requirements are that—
(a)the accident or defect is reported at the earliest opportunity to the Certifying Authority that issued the Sewage Certificate in respect of the ship; and
(b)in the case of a ship in a port outside of the United Kingdom, the accident or the defect, as is immediately reported to the appropriate maritime authorities in the State in which the port is situated.
(5) Whenever an accident or defect is reported to a Certifying Authority in accordance with paragraph 4(a), the Certifying Authority must—
(a)cause an investigation to be initiated to determine whether or not an additional survey is necessary; and
(b)if it considers that an additional survey is necessary, cause that survey to be carried out.
(6) Whenever an accident or defect is reported to a Certifying Authority in accordance with paragraph (4)(a) and the ship in question is in a port outside the United Kingdom, the Certifying Authority must take all appropriate steps to ascertain that the requirement in paragraph (4)(b) has been complied with.