19.—(1) A ship to which this paragraph applies must not proceed to sea from a port in the United Kingdom unless—
(a)a Sewage Certificate has been issued pursuant to Annex IV in respect of that ship and is still valid,
(b)a surveyor of ships is satisfied that the ship can proceed to sea without presenting an unreasonable threat of harm to the marine environment, or
(c)a person having powers to detain the ship has permitted the ship to proceed to sea for the purposes of proceeding to the nearest appropriate repair yard available.
(2) A ship to which this paragraph applies must not proceed to sea from a port in the United Kingdom unless documentation has been issued in respect of that ship which is still valid and shows that—
(a)a survey has been carried out in respect of the ship as if regulation 7 applied to the ship, and
(b)a surveyor of ships is satisfied that the ship can proceed to sea without presenting an unreasonable threat of harm to the marine environment, or a person having powers to detain the ship has permitted the ship to proceed to sea for the purposes of proceeding to the nearest appropriate repair yard available.