Hudson Shipping Lines (HSL) has doubled down on its stance against using exhaust gas scrubbers to meet pending IMO 2020 regulations.

The US ship operator has joined Trident Alliance, a group of shipping companies focused on ensuring full enforcement of pending IMO 2020 rules.

Four months ago, it said publicly that it would boycott scrubber-fitted vessels on the premise that they transfer airborne ship exhaust into the ocean.

“The shipping industry has a tremendous opportunity to improve its impact upon the world with the IMO 2020 sulphur cap," president Avi Eilon said in a statement.

"Hudson believes it has a responsibility to encourage companies and countries to comply with both the letter and also the spirit of the sulphur rules."

To that end, HSL reaffirmed its promise in June to work with other companies in an all-out effort to rid shipping of scrubbers once and for all.

"While Hudson intends to work with the Trident Alliance on enforcement of sulphur regulations, Hudson will be supporting organizations that lobby countries, customers, producers and ports to ban exhaust gas scrubber systems, and encourage shipowners and the banks and financiers who finance their operation to cease their use and installation," the company said.

HSL said its Trident Alliance membership is part of ongoing efforts to ensure that shipping lives up to standards set by the global sulphur cap.

"Hudson will work with and within the Trident Alliance to ensure robust enforcement of all maritime sulphur regulations and develop new technologies to monitor ships’ compliance with the regulations," HSL said.

"Hudson also believes that the current form of sulphur regulations contains a major loophole that is being abused by irresponsible shipowners to allow the continued use of high sulphur fuel oil (HSFO)."

Trident Alliance lists 51 shipping companies on its website as members — some of which use scrubbers, including Stena, Maersk and Scorpio Group.

This story has been amended to reflect Trident Alliance's stance on scrubbers.