The International Maritime Organization (IMO) is concluding its revision of the Initial IMO Strategy on Reduction of GHG Emissions from Ships in July 2023. A major issue in the revision is the question whether to set an emission reduction target for 2030 and if so, how high it should be. As an input to the debate, CE Delft has modelled the maximally technically achievable reduction potential for the sector with its CE-Ship model. Assuming that ships take all possible technical abatement measures available, including the maximal deployment of wind-assisted technology, reduce their speed by 20-30% and use 5-10% zero-GHG fuels, we find that the emissions of international shipping can be reduced by 28-47% by 2030, relative to 2008. Such a reduction would increase shipping costs by 6-14% on average, relative to BAU. About half of the emission reductions result from lower speeds and other operational measures, a quarter from wind-assisted propulsion and other technical measures and another quarter from using zero and near-zero GHG fuels.