HomeCalculatorsEPL Required MCR Reduction

EPL Required MCR Reduction

Compute the limited MCR (kW) required to bring a ship's attained EEXI down to a target value, the percentage reduction relative to the original MCR, and the corresponding speed loss using the cubic-law approximation. Supports the EEXI compliance check under MARPOL Annex VI Regulation 25 with EPL or ShaPoLi as the compliance mechanism.

EEXIEPLShaPoLi

Ship inputs

Attained EEXI before limitationg CO₂ / (t·nm)Calculated from the EEDI formula using the original installed MCR. Use the EEXI Attained calculator with the original MCR if needed.Required EEXIg CO₂ / (t·nm)From the EEXI Required calculator. The limited MCR brings attained EEXI to this value.Original installed MCRkWTotal maximum continuous rating of the main engine(s) as installed on the ship before any limitation. From the EIAPP Certificate.Reference design speedknotsDesign speed at 75% of the original MCR in calm-water conditions. From the EEXI Technical File.

Required limited MCR

5,774kW

Sea trial verification per MEPC.366(79) required at first survey.

MCR reduction

23.0%

Estimated speed at limited MCR

13.29knots

Cubic-law estimate; verify on sea trial.

Speed loss

8.3%

Formula, assumptions, and limits

The 3/2 exponent reflects the combined cubic speed-power relationship (P ∝ v³) and the linear power-CO₂ relationship at constant SFC (CO₂ ∝ P). The attained EEXI scales as MCR^(2/3) at constant capacity, distance and Cf.

Speed loss from the cubic-law approximation. For low-speed ships and unusual hull forms (e.g. bulbous bow optimised for a single design speed), the actual speed loss may be larger than the cube-root estimate; verify with sea trial under MEPC.366(79).

Symbol legend

Meaning	Unit	Source
Original installed maximum continuous rating	kW	EIAPP Certificate
Required limited maximum continuous rating	kW	result
Attained EEXI before limitation	g CO₂ / (t·nm)	EEXI formula at original MCR
Required EEXI for the ship type and size	g CO₂ / (t·nm)	MEPC.328(76) reduction factor table
Reference design speed (75% original MCR)	knots	EEXI Technical File
Estimated speed at limited MCR	knots	cube-root scaling

The limited MCR must remain at or above the Minimum Propulsion Power required by IMO MEPC.232(65); verify before finalising the limitation. Override the regulatory minimum at your peril - the ship will fail the heavy-weather safety check and the EEXI compliance approval will be refused.