🔔 Subscribe to ShipUniverse Weekly →
Air lubrication systems turn the flat bottom of a big ship into a moving carpet of bubbles. Instead of dragging steel through dense water, the hull rides on a thin air layer, which cuts friction, trims fuel consumption and lowers CO₂. After a decade of trials, the tech is now on more than a hundred large vessels, with reported net savings typically in the 4–10 percent range depending on hull form and trade.
What is it and Keep it Simple...
Air lubrication systems (ALS) pump controlled air under the flat bottom of a ship so the hull rides on a layer of bubbles instead of full-contact water. Less contact means less friction, which means less power needed for the same speed.
In practice, compressors feed air to nozzles or air release units under the hull. These create a steady carpet of microbubbles that clings to the bottom plating as the ship moves. The system is normally active at service speeds and switched off when alongside, in shallow water or at very low speeds where it brings less benefit.
Owners use ALS as one of several energy efficiency tools. Typical goals are lower fuel burn, better CII and EEXI margins, and lower EU ETS exposure per voyage. The big questions are: what is the real net fuel saving after compressor power, how robust is it across drafts and sea states, and how easy is it to retrofit on existing hulls.
2025–2026 Air Lubrication: Is It Really Working?
- Verified fuel savings: Sea trials and early fleets are confirming net fuel savings in the mid single digits, with some higher numbers on well matched hulls and steady-speed trades. The headline figure varies, but owners that log “ALS on” status and normalised fuel use see a consistent gap compared with periods when the system is off.
- CII, EEXI and ETS support: Because ALS cuts shaft power for a given speed, it improves CII and EEXI margins and trims EU ETS exposure. The effect is strongest on high fuel burn routes where even a modest percentage saving is worth a lot in allowances and bunker spend.
- Best fit segments: Large tankers, bulkers, LNG carriers and cruise ships with broad flat bottoms and relatively stable drafts are seeing the most consistent performance. Vessels with complex hull forms or fast changing drafts tend to see more variation in benefit.
- Reliability and maintenance: The core equipment is mature (compressors, piping, valves), and most issues are about keeping air release units clean and checking that measured power savings still match expectations. Where owners link ALS health checks to underwater inspections and performance dashboards, issues are usually caught early.
- Crew workload: When control is automated and indications are simple, crews report that ALS becomes another background efficiency system. Where controls are manual, unclear or poorly integrated, the system is more likely to be switched off or used inconsistently, which hurts payback.
- What still limits scale: High CAPEX and drydock time, uncertainty about long term savings on some trades, and the need for robust data to convince charterers and finance teams are the main brakes. The strongest projects are the ones that treat ALS as a measured efficiency project with clear baselines and voyage by voyage evidence, not just a one time retrofit.
Notable Air Lubrication Suppliers to Watch
Links are external, no affiliation impliedDedicated air lubrication provider with a large orderbook across LNG, container, cruise and other segments, focused on a patented microbubble carpet under the flat bottom.
Best fit: high fuel consumers with broad flat bottoms and steady trade patterns.
Visit Silverstream website ↗OceanGlide combines air lubrication with fluidic technology, using air distribution bands to create a controllable air layer and reduce drag with relatively modest compressor demand.
Best fit: newbuilds and retrofits where flexible compressor placement and minimal hull penetrations are important.
Visit OceanGlide page ↗The Mitsubishi Air Lubrication System (MALS) is one of the earlier large-scale ALS solutions, developed for bulkers, ferries and passenger ships to cut viscous resistance with a controlled air layer.
Best fit: projects linked to Japanese shipyards or designs with prior MALS experience.
Visit MHI website ↗Wärtsilä integrates air lubrication into broader efficiency packages, combining ALS with propulsor upgrades, shaft generators and voyage optimisation for whole-ship energy gains.
Best fit: owners looking at combined retrofit packages rather than a single technology in isolation.
Visit Wärtsilä efficiency page ↗Names shown here are examples based on publicly available information and should not be treated as recommendations. Always compare multiple suppliers, reference lists and class documentation before making any commitment.
For most owners, air lubrication is a classic “measure and prove” efficiency project rather than a quick win. The physics are sound and real fleets are seeing useful savings, but the business case depends on hull shape, trades, fuel and carbon prices and how consistently the system runs. If you treat ALS like any other capital project, log on or off status in your performance data and compare normalised fuel and ETS exposure before and after installation, you will quickly see whether it is a core part of your decarbonisation toolkit for that vessel or a nice idea that is better reserved for a different hull or trade.
We welcome your feedback, suggestions, corrections, and ideas for enhancements. Please click here to get in touch.