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HomeAir Lubrication Systems Made Simple: 2026 Update
Air Lubrication Systems Made Simple: 2026 Update
December 2, 2025
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.
Air Lubrication Systems: Advantages and Disadvantages
Category
Advantages
Disadvantages
Notes / Considerations
Fuel, emissions and CII
✅ Proven net fuel savings in many projects, typically in the 4–10% range, with some higher figures in favourable cases.
✅ Direct reduction in CO₂ and other exhaust emissions, which improves CII rating and EEXI margin and can reduce EU ETS cost per voyage.
❌ Real savings depend on hull form, loading, speed profile and how consistently the system is used.
❌ If compressor power is high or control is poor, net gains can drop noticeably.
Ask vendors for net saving figures verified by class or third party measurements, not just model scale or gross drag numbers.
Retrofit and newbuild fit
✅ Newbuilds can be designed around ALS with flat bottom areas and good access for compressors and piping.
✅ Several vendors now offer retrofit packages for large tankers, bulkers, LNG and cruise vessels.
❌ Complex hull shapes, steps or limited flat bottom can reduce the effective air carpet and savings.
❌ Retrofitting may need substantial steel work, fairing and drydock time.
Screen fleet for flat bottom area, typical drafts and remaining life before committing to wide retrofit programmes.
Operations and robustness
✅ Once tuned, systems can run automatically at defined speeds and drafts with limited crew input.
✅ No direct change to main engine or fuel system, so operational risk is mostly around availability rather than new failure modes.
❌ Performance can vary in heavy seas, shallow water and at very low speeds.
❌ Fouling or damage to air release units can degrade performance and require underwater work.
Use clear operating envelopes and simple bridge or engine room indications showing when the air carpet is within design range.
Integration and class
✅ Class guidance and notations now exist for ALS design, installation and survey, which provides a clearer approval path.
✅ Systems can be integrated with automation and performance monitoring to log on or off status and support MRV and ETS reporting.
❌ Additional sensors, controls and alarms must be integrated into existing automation without overloading crews.
❌ Class requirements may add instrumentation, redundancy and testing cost compared with early pilot systems.
Use vendor designs that follow recognised class guidance and ensure documentation and sea trial plans are agreed early.
Maintenance and reliability
✅ Simple mechanical components (compressors, piping, valves) and static air release units are generally well understood by crew and service partners.
✅ Condition based checks and routine inspections can be tied into existing drydock and underwater inspection cycles.
❌ Any loss of compressor capacity or blocked air release units can reduce the air carpet and shrink savings without obvious bridge alarms.
❌ Additional underwater inspections or cleaning may be needed, especially in high fouling waters.
Define simple KPIs such as minimum differential pressure, compressor load and fuel saving trend that trigger inspection of the ALS.
Commercial, ETS and chartering
✅ Lower fuel per tonne mile improves competitiveness on bunker intensive routes and supports better CII scores in charter discussions.
✅ For EU ETS trades, validated fuel savings translate directly into lower allowance purchases for owner or charterer.
❌ Charterers may question savings until they see data across multiple voyages and loading conditions.
❌ Commercial benefit allocation (owner versus time charterer) can be sensitive and may require tailored clauses.
Capture ALS on or off status and net fuel deltas in performance reports so commercial teams can evidence the benefit in negotiations.
Cost, ROI and project risk
✅ For high fuel consumers on steady trades, multi percent verified savings can pay back CAPEX within a few years.
✅ Technology is now supported by several established vendors with growing reference lists across multiple ship types.
❌ High upfront CAPEX and drydock costs make ALS a significant investment, especially for older ships with limited remaining life.
❌ Savings that are only realised under narrow operating profiles can stretch payback beyond what finance teams accept.
Run a route specific business case that includes compressor power, realistic sea states, charter profile and remaining vessel life before committing.
Summary: Air lubrication systems turn a ship’s flat bottom into a controlled bubble carpet that cuts friction and fuel consumption. The upside is direct and measurable energy saving and lower emissions on suitable hulls and trades. The downside is the CAPEX, added complexity and the need for robust performance data to prove net benefit across real world loading, draft and sea state conditions.
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.
Air Lubrication Systems — Fuel, ETS and ROI
Training values — replace with your own data
Baseline Fuel and ALS Effect
Costs, Finance and Utilisation
Sensitivity
Net fuel saved (tonnes per year)
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Fuel and ETS saving (USD per year)
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Net annual benefit (after ALS OPEX)
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Payback (years, discounted)
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NPV over analysis horizon
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Implied IRR
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This tool is for training and pre-feasibility. It combines a simple fuel and ETS saving model with high level cost
assumptions for an air lubrication retrofit or newbuild. Replace all values with your own bunker data, vendor
quotes, measured performance and project budgets, and align assumptions with class, flag and finance requirements
before making any investment decision.
Notable Air Lubrication Suppliers to Watch
Links are external, no affiliation implied
✅ Established specialist
Silverstream Technologies
Dedicated 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.
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.
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.
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.
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.
