Crude Oil Washing or COW

Crude Oil Washing or COW. The carriage of oil cargoes was strongly controlled from 1954.

The most recent international agreement is contained in the “International Convention for the Prevention of Marine Pollution from Ships 1973” as amended in 1978. This is known as “MARPOL 73/78”. One of the provisions in MARPOL is that during the discharge operations crude oil can be used to wash the cargo tanks so as to clean them sufficiently for the carriage of ballast. The ballast will not be “dirty ballast” which is now generally restricted from being discharged into the sea. Moreover, from a practical point of view, cleaning tanks with crude oil also tends to dissolve the sediments and residues and so improve cargo out turn.

COW requires special training and qualifications of the vessel’s staff and this may be the subject of clauses in tanker charterparties. The time taken for COW may also influence the laytime for cargo operations. If the additional time taken because of COW is increased by breakdown of tank washing equipment, the time last may not be counted as laytime. If port authorities require COW, the charterparty should make it clear which side pays for the time used. In BEEPEEVOY 2 ’83, the COW clause states:

“Owners undertake that the vessel is equipped with a fully functional Crude Oil Washing System and that the officers and crew are experienced in the operation of such System. If so requested by Charterers in their voyage instructions the maser shall arrange for the crude oil washing of cargo tanks at the discharge port to be effected contemporaneously with cargo discharging operations. Any additional time consumed by reason of the effecting of crude oil washing on Charterers’ instructions shall count as used laytime or, if the vessel is on demurrage, for demurrage, save and except for any time lost owing to deficient or improper operation of the Crude Oil Washing System.”


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Written by Ship Inspection

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Cover note

CPT (carriage paid to … the named place of destination)