Answer
“As CE, for engine derating I will send the company and engine maker the engine particulars and present MCR/rpm, complete recent performance report including indicator cards, Pmax/Pcomp, exhaust temperatures, scavenge pressure, turbocharger rpm and fuel consumption. I will also provide vessel speed–power–rpm data, draft/displacement and weather conditions, together with propeller particulars and load diagram. I will state the existing MCR and the proposed derated kW/rpm. The maker will then verify whether the new rating is within the engine layout diagram and advise any changes required to fuel injection, turbocharger matching and NOx certification.”
As Chief Engineer, for engine derating I would provide:
- Engine maker, model, serial no., present MCR/NCR in kW and rpm
- Proposed derated power and rpm
- Recent engine performance report
- Indicator cards, Pmax, Pcomp, indicated power
- Fuel consumption and fuel index
- Scavenge pressure/temp
- Exhaust temperatures cylinder-wise
- Turbocharger rpm
- Cooling water and lube oil temperatures/pressures
- Ship speed, draft, displacement, shaft rpm/power
- Propeller details: FPP/CPP, diameter, pitch, number of blades
- Existing engine load/propeller diagram
- Engine running hours and general condition
- EIAPP/NOx Tier and NOx Technical File details
For EEXI compliance, IMO permits EPL/SHaPoLi as an overridable power-limitation system. For an EPL system, the technical documentation specifically includes the original rated installed power and rpm, limited power and rpm, and the method used to seal/lock and monitor the limitation.
A permanent derating, on the other hand, can involve OEM recalculation and modification of the engine's approved rating/settings, so maker and Class/Flag involvement may be required, including review of the NOx Technical File/EIAPP certification where applicable.