The capacity-normalised operational CO₂ metric for ships where gross tonnage is the better capacity basis than deadweight - ro-pax, ro-ro vehicle carriers, and cruise ships per MEPC.337(76).
Formula
$$ \text{cgDIST} = \frac{\sum_j F_j \cdot C_{f,j} \cdot 10^6}{\text{GT} \cdot \text{Distance}} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $\text{cgDIST}$ | Gross-tonnage-normalised CO₂ intensity | g CO₂ / (GT·nm) | result |
| $F_j$ | Mass of fuel $j$ burned | t | IMO DCS |
| $C_{f,j}$ | CO₂ conversion factor for fuel $j$ | t CO₂ / t fuel | MEPC.364(79) |
| $GT$ | Gross tonnage | - | ITC-69 tonnage certificate |
| $Distance$ | Distance sailed in the reporting period | nm | IMO DCS |
| $10^6$ | Unit conversion tonnes → grams | - | constant |
Same math as AER with GT replacing DWT. A cruise ship at GT 100,000 burning 20 kt VLSFO over 200,000 nm typically hits ~3.1 gCO₂/(GT·nm).
Sources
- IMO MEPC.336(76) - operational CII guidelines.
- IMO MEPC.337(76) - reference lines (GT-based rows for passenger and ro-ro types).
- IMO MEPC.364(79) - Cf conversion factors.