While use of an open-loop scrubber is permitted under MARPOL Annex VI, an increasing number of ports are placing more stringent restrictions on their use including prohibition of the discharge of washwater in port or territorial waters, or only allowing it under certain conditions. For a ship with an open-loop scrubber, this then means that the ship will have to use low sulphur fuel oil.
It is expected that more States will prohibit the discharge of washwater from open-loop scrubbers into their territorial seas and/or inland waterways. Owners who have open-loop scrubbers are advised to check with local agents for up-to-date requirements when conducting their voyage planning. Check also with your P&I Club as many are compiling lists.