(1) The general rule is that service of a warrant of arrest or claim form in proceedings in rem against a ship, freight or cargo is to be effected by —
(a) affixing the warrant or claim form for a short time on any mast of the ship or on the outside of any suitable part of the ship's superstructure; and
(b) on removing the warrant or claim form, leaving a copy of it affixed —
(i) (in the case of the warrant) in its place, or
(ii) (in the case of the claim form) on a sheltered, conspicuous part of the ship.
(2) However, service of a warrant of arrest or claim form in proceedings in rem against freight or cargo or both, if the cargo has been landed or transhipped, is to be effected —
(a) by placing the warrant or claim form for a short time on the cargo and, on removing the warrant or claim form, leaving a copy of it on the cargo; or
(b) if the cargo is in the custody of a person who will not permit access to it, by leaving a copy of the warrant or claim form with that person.