Slow Steaming Savings

Compare fuel and CO₂ for a voyage at two speeds. Holds distance constant, scales main-engine fuel by V^n and adds aux consumption that rises with extra voyage hours.

VoyageSlow steaming

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This calculator requires JavaScript to compute its result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

F_\text{slow} = \left(\text{ME}_\text{ref} \cdot \left(\frac{V_\text{slow}}{V_\text{ref}}\right)^n + \text{AE}\right) \cdot \frac{D / V_\text{slow}}{24}

Symbol	Meaning	Unit
$F_\text{slow}$	Voyage fuel at slow-steaming speed	t
$\text{ME}_\text{ref}$	Main-engine daily fuel rate at reference speed	t / day
$V_\text{ref}$	Reference speed	kn
$V_\text{slow}$	Slow-steaming speed	kn
$n$	Speed exponent (≈ 3)
$\text{AE}$	Auxiliary + boiler daily fuel rate (speed-independent)	t / day
$D$	Voyage distance	nm

Source: MAN Energy Solutions - *Propulsion Trends*; IMO MEPC.364(79) - Cf conversion factors

In short

Compare fuel and CO₂ for a voyage at reference and slow-steaming speeds with cube-law main-engine scaling and constant aux consumption.

Learn the theory Voyage Estimation: TCE, Bunkers, and Canal Economics