As more shipowners adopt slow steaming to reduce fuel consumption and emissions, maritime consultancy Houlder warns that without data-driven analysis, the practice may lead to unintended financial impacts and potentially hinder progress towards the IMO’s greenhouse gas reduction targets.

Slow steaming, the practice of operating vessels at reduced speeds, can influence vessel efficiency in various ways, depending on a ship’s original design, hydrodynamic performance, and operational profile. Houlder’s analysis of Clarksons’ data reveals a marked decline in average service speeds across multiple vessel types—oil tankers, bulkers, and container ships—from 2012 to 2024. Container ships experienced the greatest slowdown, with an average speed reduction of 1.50 knots (-11%) by 2024, followed by bulk carriers (-9%) and oil tankers (-6%).

While slow steaming can reduce power consumption and GHG emissions, it may also deviate significantly from a ship’s design parameters, impacting both performance and maintenance costs. Iebum Shin, data analytics lead at Houlder, cautions that “simple retrofits such as hull modifications or propeller optimisation could determine whether slow steaming delivers marginal or substantial benefits.”