An assessment of the revised carbon intensity indicator for a training ship using a cruise ship-based similarity index

This study examines the feasibility and validity of applying the Carbon Intensity Indicator (CII) to training ships, which currently occupy a regulatory blind spot within the International Maritime Organization’s (IMO) decarbonization framework. While previous research often used Ro-Ro passenger ships as a reference, those models fail to reflect the unique structural and operational profiles of training ships.To address this, this research analyzed empirical technical data—including the Length-to-Beam ratio, Block Coefficient, Gross Tonnage, and annual sailing distance—from three distinct training ships. The analysis demonstrates high structural similarity between training ships and cruise ships, thereby establishing a new reference vessel category.The Attained CII was derived using both pre- and post-revision calculation methodologies. A comparative analysis with the Required CII (incorporating the Z-factor) revealed that the vessels’ ratings significantly improved from “E” under pre-revision criteria to “A” or “B” under the revised formula.These findings suggest a strong potential for including educational and public-purpose vessels in future IMO frameworks. Ultimately, this study provides foundational implications for designing carbon management systems tailored to special-purpose vessels.