Gains:
- Ability to calculate energy efficiency and carbon intensity indicators such as EEXI, EEDI and CII with correct definition and formula with AI
- Ability to compare emission reduction (decarbonization) options in terms of cost-benefit with AI support
- Ability to audit AI's efficiency and emissions calculations with IMO/MARPOL rule and verified data
While shipping carries the majority of world trade, it is a significant source of greenhouse gases and air pollution. That's why the International Maritime Organization (IMO; the UN organization that regulates safety and pollution from ships) has introduced rules one after another. Today every ship; It is measured and rated in terms of energy efficiency and carbon intensity, and this rating directly affects its commercial value. Artificial intelligence (AI) makes it faster to set up these accounts, compare scenarios, and draft compliance reports. However, these indicators are defined by official formulas, and a miscalculation will lead to a penalty, poor rating, or breach of contract.
Critical principle: No EEXI, CII or emissions number issued by AI will become a declaration of compliance without being confirmed with the current official text of the relevant IMO/MARPOL formula and verified input data. The denominator, coefficient and limit values in the formulas are updated over time; The value in the AI's memory may be old or made up.
Concepts: EEXI: Existing Ship Energy Efficiency Index; a measure of the ship's design efficiency. CII: Carbon Intensity Indicator; The annual carbon emissions per job carried by the ship are graded from A to E. MARPOL: Convention on the prevention of pollution from ships. SEEMP: Ship energy efficiency management plan. EEDI: Design efficiency index for newbuilding ships. DWT/nm: Relationship between deadweight and distance traveled; carbon intensity denominator.
CII: Is the Denominator Correct?
CII is the most commonly mistaken indicator because it is a ratio: carbon emitted annually divided by the “transportation work” moved. In the common CII format, the denominator is the ship's capacity (or the cargo it carries) multiplied by the distance it travels. So CII measures not just "how much fuel you burned" but "how much work you burned". Therefore, if the ship travels a lot or carries a lot of cargo, the density decreases (improves); simply looking at the distance and subtracting the load/capacity from the denominator completely miscalculates the gauge.
When AI sets up a CII account, the first thing to check is the denominator: are the correct capacity/load and distance used, are the units consistent, are the base year and reduction factor correct? Second control, carbon conversion: fuel consumption is multiplied by the fuel type-specific carbon emission factor (CO₂ per fuel); the wrong factor shifts the entire result. Third check, rating limits: A-E rating thresholds vary by ship type and size and tighten annually; The threshold used by the AI must be verified from the current official table.
Caution: In CII, the denominator error is the most common and most insidious error. Removing payload or capacity from the denominator and using only distance can make a hard-working, efficient ship look inefficient, and vice versa. In every CII output, first ask "what is the denominator, what is its unit, is it correct?"
EEXI, SEEMP and Mitigation Strategies
EEXI measures design efficiency for existing ships and is compared to an upper limit; Ships crossing the border must take precautions. The most common adaptation measure is power limiting (EPL/ShaPoLi; throttling the certified power of the engine to a certain limit), energy efficiency devices (propeller improvements, hull optimization) or operational measures. AI models the impact of these measures on EEXI; But whether the power limitation leaves the ship with sufficient power for maneuvering and safety in heavy weather (sufficient minimum power rule) is a separate safety check and requires class approval.
SEEMP is the plan for how the ship will manage efficiency and includes CII improvement targets. AI can produce action lists, monitoring plans, and reporting frameworks for SEEMP; but the impact of every numerical target and every measure in the plan is verified by real data.
indicator
What does it measure?
frequent error
verification
EEXI
Design efficiency (current ship)
Incorrect reference/correction factor
Current IMO formula + classy
CII
Annual carbon intensity
Setting up the denominator incorrectly
Capacity×distance, current threshold
EEDI
New ship design efficiency
Using old phase boundary
Current phase requirement
Carbon factor
CO₂ conversion from fuel
Incorrect fuel factor
Official factor table
Mini Cases
Case 1 — CII without denominator. When calculating a ship's CII, a crew uses only the distance traveled in the denominator, forgetting the carrying capacity/cargo. The result completely misrepresents the ship's true density; A productive campaign looks like a bad one. In the correct formula, the denominator is the product of capacity and distance. When the team corrects the denominator, the degree improves by one level. Lesson: CII is a ratio; If the denominator is wrong, everything is wrong.
Case 2 — Old degree threshold. One report calculates the CII grade as "C" with the threshold table from several years ago. However, CII thresholds get tighter every year; According to the current table, the same performance now corresponds to a "D" rating. The ship is at risk of a closer alignment than it realizes. Lesson: degree thresholds change annually; Each account is verified from the current official table.
Case 3 — Power limiting safety. A ship considers power limiting for EEXI compliance; AI finds the measure positive in terms of efficiency. However, the limited power may fall below the minimum power required for safe maneuvering of the ship in heavy weather conditions. Klas does not approve restraint without considering the minimum force rule. Lesson: an efficiency measure cannot violate a safety rule; Power limitation requires class approval.
Copiable Prompt Templates
Template 1 — CII account configuration (denominator controlled):
Role: You are a maritime energy efficiency expert.Context (representation): [ship type/size], annual fuel consumption[fuel type and quantity], annual distance traveled, capacity/load.Task:1) Set up the CII with the correct formula; write clearly what the denominator is.2) State the carbon factor you used in the conversion from fuel to CO₂.3) You used degree thresholds; mark "verify from official table" that these must be up to date. Constraint: emphasize that the formula and thresholds must be confirmed from the current IMO text; Don't count the value in your memory accurately.
Template 2 — EEXI precaution scenario:
A ship exceeds the EEXI limit (representative). Compare compliance measures: power limitation (EPL/ShaPoLi), propeller/hull improvement, operational measures. For each measure: estimated impact on EEXI, cost, difficulty of implementation. Constraint: Mark as "class approval required" if power limitation violates the minimum power (heavy air maneuvering safety) rule. Make final decision.
Template 3 — SEEMP action and monitoring framework:
Produce a skeleton for a SEEMP:1) List of CII improvement measures (route, trim, speed, maintenance).2) Expected impact for each measure and how it will be measured.3) Monitoring and reporting plan.Constraint: Mark each numerical target as "to be verified with real data"; do not give a made-up savings percentage.
Template 4 — Emission result reasonableness check:
Critique the following emission/CII result:[paste calculation and inputs]1) Is the denominator set up correctly (capacity×distance)? Are the units consistent?2) Is the carbon factor for the correct fuel type?3) Is the rank threshold up to date?4) Is the order of magnitude consistent with similar ships?Mark each questionable item and write how to verify it.
Weak prompt / Strong prompt
Weak prompt:
Calculate this ship's CII and rating.
Powerful prompt:
Role: You are a marine environmental compliance expert.Context (representation): bulk carrier, annual fuel [x t VLSFO], annual distance [y nm], capacity [z DWT].Task: Calculate CII with correct formula; clearly show the denominator; specify the carbon factor and rating thresholds. Constraint: Check that the formula, carbon factor and thresholds must be verified from the current IMO official text; Don't count the value in your memory precisely. Compare the result with similar ships in order.
The weak prompt doesn't ask for the denominator or currency check at all; The strong prompt formula explicitly requests the factor, threshold, and verification.
Common mistakes
- Setting up the CII denominator incorrectly. Forgetting the capacity/load and using only distance completely distorts the indicator.
- Using old degree threshold. CII thresholds tighten annually; It should be verified from the current official table.
- Wrong carbon factor. If the CO₂ factor specific to the fuel type is erroneous, the entire emissions result will shift.
- Implementing power limitation in an unsafe manner. Power constraint for EEXI, heavy weather cannot violate minimum power rule; class approval required.
- Mistaking AI's formula for official. IMO formulas are updated; The value in the AI's memory may be old/fabricated.
In summary
EEXI and CII are indicators that measure the efficiency and carbon intensity of the ship with official formulas and directly affect the commercial value. AI makes it faster to set up these calculations and compare scenarios; but in CII, the denominator is always controlled with the logic of "capacity × distance", degree thresholds and carbon factors are verified from the current official text, measures such as power limitation cannot violate safety rules. Declaration of conformity is based on verified accounting and class approval.
Application task
Have AI set up a CII calculation for a representative ship (ship type, annual fuel, distance, capacity) and query whether the denominator is correct with the "emissions result plausibility check" template. Mark the carbon factor and rating threshold as "verify from official table". Then propose a set of EEXI/operational measures for the ship to upgrade and write how you will verify the effectiveness of each measure. If you recommend power limiting, note the safety constraint.
checklist
- [ ] I checked the CII denominator (capacity×distance) and its units.
- [ ] I verified that the carbon emission factor is for the correct fuel type.
- [ ] I have confirmed that the rank thresholds come from the current official table.
- [ ] I checked the power limiting recommendations with the minimum power/safety rule.
- [ ] I have verified AI's formulas and constants with the current IMO/MARPOL text.
- [ ] I have based the declaration of conformity on the verified account and the required class approval.