Class societies are actively collaborating with yards and manufacturers to ensure successful and timely engine retrofit projects, but there are challenges.

There are practical challenges when it comes to the testing and certification of the exhaust gas emissions of engines after they have been retrofitted, says Dr Fabian Kock, Head of Section at DNV, citing Regulation 13 of MARPOL Annex VI (Nitrogen oxides (NOx)) and the NOx Technical Code 2008.

“These regulations do not cover a detailed procedure for how to improve the performance of existing marine diesel engines that are installed onboard a ship and which cannot be tested on test beds retroactively. One could say that the requirements of the NOx Technical code are somehow hindering the development of new technologies when retrofitting already certified engines on board of existing vessels,” he says. “This dilemma has just recently been addressed to IMO MEPC80.”