Engine
Indicated power
The power developed in the cylinders, from the mean indicated pressure of the indicator cards or the cylinder pressure monitor, and the mechanical efficiency against the shaft power.
For mechanical efficiency
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How it works
Indicated power = pmi × A × L × n × z: mean indicated pressure (Pa) × piston area (m²) × stroke (m) × power strokes per second × cylinders. A two-stroke engine has one power stroke per revolution, a four-stroke one every two.
The shaft (brake) power is less by the friction losses: mechanical efficiency = brake power / indicated power, usually 0.85–0.95. Compare cylinders with each other: one with a lower pmi is doing less work.
For training and cross-checking. Not a substitute for approved navigation equipment, nautical publications and the ship’s own procedures. Calculations run in your browser and nothing you type is stored; a PDF you download is made on our server and not kept.
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