As we continue the push towards global decarbonization, the International Maritime Organization’s (IMO) GHG strategy is aiming to reduce the carbon emissions of the global fleet by 40% by the year 2030 and is targeting a 70% reduction in CO2 emissions by 2050. The Greenhouse Gas Strategy was approved by the IMO in 2018, and the reduction rates are compared to the baseline year of 2008. Short-term improvement measures including energy efficiency requirements for large ships are to be effective January 1, 2023. For example, the Energy Efficiency Existing Index (EEXI) is a method for regulating the speed and power limitations of ships and is applicable for all vessels above 400 GT falling under MARPOL Annex VI.1
The roughness of a ship’s hull surface affects its hydrodynamic performance and tends to increase due to the age of the ship, improper paint application, coating damage, wear, and biofouling. An increase in hull roughness leads to an increase in a vessel’s fuel consumption and greenhouse gas (GHG) emissions. This phenomenon is becoming a greater issue for ships as there is an ever-increasing pressure from regulators to implement energy-efficiency measures. Another example of this, is IMO’s Carbon Intensity Indicator (CII), which is an operational efficiency parameter for ships with a gross tonnage over 5,000 GT.1 Both the EEXI and CII measures will lead ship owners to invest in energy-saving devices via retrofit or reduce the operational carbon emissions of their vessels via engine power limitation.1 Based on previous research in the field of ship energy and efficiency and the role of hull coatings, the CII parameter will be affected by the vessel owner’s choice of surface preparation, hull coating system, and ability to maintain hull and propulsive efficiency.