This insights summary serves as practical guidance for shipowners and charterers considering or currently operating an active air lubrication system (ALS) on board vessels in their fleet. The technical findings shared in this publication were collected via a stakeholder group formed in January 2026. The stakeholder group consisted of shipowners and charterers with experience operating ALS across multiple segments (Figure 1). The group uncovered recurring patterns and common bottlenecks, while also pointing towards operational best practices that could be shared across the industry.

Insights collected by the stakeholder group are limited to the experience of that group. Hence, this summary is not intended to reflect the industry standards of all the different existing ALS applications across all shipping segments and sizes. Our ambition in future work is to expand our views, taking an ecosystem perspective with other stakeholders, and further explore the opportunities to understand how actual operations can help improve ALS technology to increase the energy efficiency of the fleet in the coming years.

Figure 1: Stakeholder group’s experience with air lubrication systems (ALS) by segment.

ALS technology aims to reduce hull friction by injecting air along the flat bottom of the vessel. Net energy savings1 reported by the stakeholder group range from 0–6% (Figure 2) and are not a representation of the industry.

Figure 2: Stakeholder group’s assessment of ALS net energy savings based on operational experience.

1'Net energy savings' refers to the actual reduction in fuel or energy consumption achieved after accounting for the additional energy required to operate the system, e.g., gross reduction in propulsion power or fuel use minus the energy consumed by compressors, pumps, or auxiliary equipment needed to run the ALS.

Estimated net energy savings differ significantly depending on: 

• Aspects of ALS or vessel design, such as hull shape and draft 

• Operational factors, such as speed profile and sea conditions (roll-motion) 

• Net savings measurement methodology 

• Integration issues in retrofits 

• Air leakage in piping systems  

• Limited understanding of physical phenomena under the hull 

• Crew training and understanding of ALS purpose 

As seen in Figure 3, vessels with large flat bottoms, high and stable cruising speeds, moderate drafts, and/or operating in calm weather conditions tend to see the greatest benefits. Differences in system design could also influence the technology's performance.

Figure 3: Stakeholder group’s assessment of vessel characteristics influencing net energy savings from ALS. Insights are solely based on operational experience from the stakeholder group’s vessels equipped with ALS.

The stakeholder group reported some common challenges with the technology, including:  

• Lack of common understanding of how to use the technology optimally (e.g., optimal air flow for different operating conditions) across vessel types and ALS designs  

• Uncertain performance measurement 

• Overestimation of efficiency gains by computational fluid dynamics (CFD) models 

• Complexity in retrofit installation 

• Limited global service support  

• Misaligned incentives between owners and charterers 

Based on their experience, the stakeholder group suggested the following best practices to ensure optimal use of ALS.  

• Newbuild integration allows optimized space utilization and air distribution 

• Plan early for compressor room, piping routes, and hull penetrations  

• Install adequate capacity for system’s power demand 

• Avoid long, leak-prone piping arrangements 

• Evaluate sea chest and appendage interactions, especially for retrofits

• Automate activation of the ALS system using thresholds, as shown in Table 1:

Table 1: Recommended operating profile for ALS depending on vessel speed and roll-in motion.

• Use ALS only at stable speed and trim  

• The higher the speed and lower the draft, the more efficient the system 

• Train crew to use ALS primarily for fuel savings, not speed increase 

• Plan for compressors’ recommended maintenance intervals (every docking cycle) 

• Renew the antifouling coating system within the air release units 

• Inspect piping regularly: minor leaks can have major impacts on the system’s efficiency 

• Monitor potential impacts on sea chest, cooling systems, and propeller cavitation (e.g., air bubbles entering sea-chest seawater can damage pumps in the reverse osmosis system) 

• Conduct long-term on/off trials campaign (several months instead of days) to measure steady-state performance 

• Automate activation of ALS for optimal utilization 

• Train crew and monitor net (not gross) savings 

• Monitor air flow quality 

The stakeholder group identified two priority areas that prevent large-scale adoption of this technology:  

1. Developing guidance for in-service measurement and utilization optimization

2. Improving understanding of below-hull physics to strengthen predictive modelling and improve savings accuracy 

The MMMCZCS is currently assessing how to best catalyze solutions for these industry bottlenecks.