HomeCalculatorsShaPoLi - Shaft Power Limitation for EEXI

ShaPoLi - Shaft Power Limitation for EEXI

Shaft-measured power-limitation variant. Math is identical to EPL; the difference is where the limitation is monitored - at the propeller shaft rather than the engine control system.

IMODesignMEPC.335(76)

Pre-limitation values

Attained EEXI without limitationgCO₂ / t·nmRequired EEXIgCO₂ / t·nmShaft power (nameplate / 100 % MCR shaft)kWUsually ~ 0.98 × engine MCR after gearbox losses.

Minimum shaft-power reduction

45.6%

Cap shaft power at 54.4 %.

Limited shaft power

4,001kW

Formula, assumptions, and limits

Shaft-power ratio = (Required EEXI / Attained EEXI before)^(3/2)

Same derivation as EPL. ShaPoLi requires a torque meter on the shaft plus an alarm/overridable limit system. EPL modifies the ME governor; ShaPoLi doesn't touch the engine. Some owners prefer ShaPoLi because the engine retains full MCR capability for safety overrides without re-declaration.