Insights from Alex Routledge in the EMSA ALS Study
In addition to its technical analysis of hull air lubrication systems, the recent study published by the European Maritime Safety Agency (EMSA) includes industry interviews with technology developers and hydrodynamic research institutions.
Among them is Alex Routledge, who provides insights into Armada Technologies’ Passive Air Lubrication System (PALS).
The interview explores how passive air lubrication systems function and some of the technical challenges associated with predicting their performance.
How Passive Air Lubrication Works
Appendix A of the EMSA report includes interviews with air lubrication technology developers and testing organizations, including insights from Armada Technologies’ Passive Air Lubrication System (PALS).
According to Alex Routledge, Armada’s system integrates specially designed pods into the vessel’s double bottom tanks, flush with the vessel’s baseline.
“Using the ship’s own forward motion, water is driven into system inlets and through specially designed venturis,” Routledge explained in the study. “This creates the suction required to draw air from deck level and produce a fine air–water mixture that is released into the vessel’s boundary layer.”
Each pod can be tuned independently to optimize performance under different operating conditions.
“By controlling water flow and venturi pressure drop, we can adjust the system to match vessel speed, draft, and sea conditions,” Routledge noted. “That allows us to maintain reliable drag reduction even as vessels operate under slow steaming or engine power limitations.”
Unlike many conventional air lubrication systems, PALS does not rely on large compressor banks. Instead, the system uses a small number of low-energy blowers to support the venturi process when needed.
“Each blower is rated at 11 kW, with two in operation and one on standby,” Routledge said. “This approach significantly reduces auxiliary power demand compared with traditional compressor-driven systems.”
Measuring Performance in Real Operating Conditions
Predicting the performance of air lubrication systems is still a challenge. Routledge explained that traditional scale-model testing is difficult because it is nearly impossible to recreate realistic microbubble behavior at model scale and then translate those results to full-scale ships. Even advanced numerical tools such as CFD have limitations when trying to simulate how bubbles behave within the turbulent boundary layer along a vessel’s hull.
Because of this, Armada has focused on collecting full-scale operational data.
The company’s first pilot installation was completed on the Kool Husky LNG carrier in October 2024, with the system installed at Yiu Lian Shipyard in China. Performance verification is being conducted through DNV-attended sea trials and long-term monitoring.
These measurements will help provide real-world operational data on the efficiency impact of passive air lubrication technology.
Improving Vessel Efficiency Through Hydrodynamics
While much of the industry’s decarbonization focus remains on alternative fuels, hydrodynamic efficiency technologies continue to play an important role in improving vessel performance today.
The insights provided in the EMSA study help shed light on how air lubrication technologies are evolving—and how developers are addressing the technical challenges associated with them.
Link to the full interview here: https://armada-technologies.com/wp-content/uploads/2026/03/EMSA-Interview-with-Alex-Routledge.ALS-Study.pdf
