Operational Guide · Registers & Logbooks

# Operational Energy Efficiency in the Engine Room

The CII rating can also be improved through levers that belong entirely to the engine room: main engine load optimization, heat recovery, and auxiliary generator management.

energy efficiency waste heat recovery shaft generator CII

## Operational Explanation

While SEEMP Part III and CII rating calculation are addressed at Company and route level in the Environmental Compliance module, the engine room has its own technical levers to contribute concretely to improving the indicator, independent of commercial decisions on speed and route.

Among the most relevant measures: optimizing main engine load within the range of maximum specific efficiency (avoiding both overload and chronic operation at very low loads), the use of waste heat recovery systems for producing steam or electrical power from exhaust gases, the use of the shaft generator to reduce reliance on fuel-fired auxiliary generators while underway, and monitoring engine performance as an indirect indicator of hull and propeller fouling.

## Regulatory Reference

Operational energy efficiency measures in the engine room support compliance with the CII rating and SEEMP Part III obligations (covered in detail in the Environmental Compliance module), without constituting a separate standalone regulatory requirement: they fall within good engine room management practices implicitly required by the need to achieve the annual target CII rating.

## Scope of Application

Every ship subject to CII reporting (≥5,000 GT under MARPOL Annex VI) fitted with heat recovery systems, a shaft generator, or engine performance monitoring tools.

## Procedure / How to Complete It

1. Monitor main engine load against the range of maximum specific efficiency indicated by the manufacturer, reporting prolonged deviations to the technical office.
2. Verify the operation and availability of the waste heat recovery system, maximizing its use when operating conditions allow.
3. Prioritize use of the shaft generator over fuel-fired auxiliary generators while underway, when electrical load conditions permit.
4. Monitor the trend of engine performance (specific fuel consumption, power per RPM) as an indirect indicator of deterioration in hull and propeller hydrodynamic performance.
5. Record and communicate to the technical office every significant deviation in performance from the historical trend, for possible scheduling of hull/propeller cleaning.

## Practical Example

Example of application: monitoring of main engine specific consumption reveals a progressive increase not explainable by load variations or weather/sea conditions, indicating possible deterioration of hull hydrodynamic performance; the information is communicated to the technical office, which schedules a hull cleaning intervention before the next routine maintenance cycle.

## Real Cases

The adoption of waste heat recovery systems and shaft generators, initially motivated by fuel cost savings, has taken on a more prominent role for CII rating purposes as annual thresholds have become stricter, making it evident that the same operational efficiency measures contribute directly both to economic savings and to regulatory compliance.

## Common Mistakes Mistake Library

Mistake | Consequence | How to avoid it
--- | --- | ---
Main engine run chronically at very low loads for commercial reasons, without monitoring the impact on specific efficiency | Specific consumption worse than expected, with a negative impact on the CII rating | Monitor and report prolonged operation outside the range of maximum efficiency
Heat recovery system available but under-utilized due to lack of clear operating procedures | Missed exploitation of an available energy saving | Define clear operating procedures to maximize use of the heat recovery system when available
Deterioration of engine performance generically attributed to 'wear' without checking the hull/propeller fouling hypothesis | Hull cleaning not scheduled in time, with growing impact on consumption and emissions | Systematically check the performance trend as a possible fouling indicator, not only engine wear

## PSC Observations

The subject is not subject to direct PSC verification, but the ship's overall energy performance (CII rating) is verifiable at documentary level together with SEEMP Part III as part of MARPOL Annex VI checks.

## Operational Tips

- Monitor main engine load against the range of maximum specific efficiency, reporting prolonged deviations.
- Maximize use of the heat recovery system and shaft generator when operating conditions allow.
- Treat deterioration of engine performance as a possible signal of hull/propeller fouling, not just normal wear.

## Checklist

- Main engine load monitored against the range of maximum efficiency
- Heat recovery system verified functional and used when possible
- Shaft generator prioritized over auxiliary generators when conditions allow
- Engine performance trend monitored as a hull/propeller fouling indicator
- Significant deviations communicated promptly to the technical office

## FAQ

Does this entry replace the SEEMP Part III covered in Environmental Compliance?
No: this entry focuses on the operational technical levers available in the engine room (engine load, waste heat recovery, shaft generator, performance monitoring), while SEEMP Part III and CII rating calculation remain covered in the Environmental Compliance module.
How does the shaft generator contribute to improving the CII rating?
By reducing reliance on fuel-fired auxiliary generators while underway, with a consequent reduction in overall fuel consumption and the emissions associated with the CII calculation.
Why monitor engine performance as a hull/propeller fouling indicator?
Because a progressive increase in specific consumption not explainable by load variations or weather/sea conditions is often the first detectable signal of deteriorating hydrodynamic performance due to fouling build-up, allowing a cleaning intervention to be scheduled in time.
🎬 Additional photos, videos and interactive diagrams for this topic will be available in a future version of the platform.

## Related Topics

SEEMP Part II/III (IT)CII (Carbon Intensity Indicator) (IT)

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