Maritime Glossary
Slow Steaming
Also known as: super slow steaming, speed optimisation
Deliberately operating a vessel below its design speed to reduce fuel consumption and CO₂ emissions.
Full Definition
Fuel consumption scales with approximately the cube of speed (the Admiralty formula); halving speed reduces fuel burn by roughly 87.5%. Slow steaming became widespread post-2008 during the shipping downturn and was reinforced by high bunker prices and CII requirements. It reduces SOx, NOx, and CO₂ per voyage but lengthens voyage times, sometimes requiring more vessels to maintain a service frequency. Optimal trim optimisation is typically applied alongside speed reduction. Main engines may require de-rating or turbocharger modifications to run efficiently at reduced power.