Shipping decarbonisation is usually discussed in the future tense: targets adopted, fuels promised, fleets to be replaced. The market data tell a more specific story. The transition is already visible in asset prices, in retrofit engineering, in the way ships are operated and in the uneven adoption of new technology. Those four kinds of evidence point to one structural feature — a two-speed fleet — and that feature, more than any fuel forecast, determines which marine equipment is in demand.
The benchmark and the fleet
The regulatory frame is set by the 2023 IMO greenhouse gas strategy (IMO, 2023), which commits international shipping to cut total annual greenhouse gas emissions by at least 20%, striving for 30%, by 2030 compared with 2008; by at least 70%, striving for 80%, by 2040; and to reach net-zero emissions by or around 2050. It also targets at least a 40% cut in carbon intensity — CO2 per unit of transport work — by 2030, and uptake of zero or near-zero GHG emission technologies, fuels or energy sources for at least 5%, striving for 10%, of the energy used by international shipping by 2030.
Two features of that benchmark matter for equipment. Several targets are fleet averages, so compliance is a portfolio problem: a company can meet an average while individual ships diverge. And the carbon-intensity target attaches to operation as well as design, which makes measurement commercially relevant. A target per unit of transport work creates a continuous incentive to measure and adjust, and continuous incentives turn regulation into demand for instrumentation, retrofits and re-specification.
The 2025 Review of Maritime Transport (UNCTAD, 2025) counts 112,500 commercial vessels of 2.44 billion deadweight tons in the world fleet on 1 January 2025, an annual increase of 3.4% against a two-decade average of 5.1%. As of May 2025, 8% of the active fleet by gross tonnage was designed to run on alternative fuels, while more than 90% of active tonnage still runs on conventional fuels. Yet 53% of the tonnage on order was designed for alternative fuels. The existing fleet and the orderbook are two different markets: one is being specified for a regulated future, the other operated, retrofitted and priced in the present.
Ownership sharpens the split. The top three flag states account for 45.1% of world carrying capacity, and the top three ship-owning nations for over 40.7%, with Greece alone at 16.4%. Large, diversified owners can carry the fixed costs of fuel transition, and their choices show in the orderbook. The rest of the fleet is fragmented among smaller owners with longer replacement cycles and more expensive capital.
Carbon performance is already in the price
The clearest sign that the transition has moved from policy to market is in secondhand values. Lu and Theocharis, 2025 study Aframax and Handymax tankers and Handysize bulk carriers sold between 2020 and mid-2023, estimating hedonic price regressions against the Carbon Intensity Indicator (CII), the Annual Efficiency Ratio (AER) and the Energy Efficiency Existing Ship Index (EEXI). They find secondhand ships priced differently by CII rating, lower EEXI and AER values associated with higher prices, and elasticities that vary by ship type.
That early evidence covers three ship types in one data window; it shows the market attaches a price to an operational rating, which changes every retrofit calculation. If a modification improves a rating, its return includes an asset-value effect as well as a fuel saving, so efficiency work becomes capital allocation rather than maintenance.
Compliance technology is a menu, not a mandate
Regulation rarely dictates a single technology. After the 0.50% global sulphur cap, Bai, Hou and Yang, 2021 trace the limit's fall from 3.5% on 1 January 2020 and analyse shipowners' energy choices using individual-ship Automatic Identification System (AIS) data and other databases. Their threshold discrete-choice model weighs ship characteristics, shipowner characteristics and market conditions, and explicitly allows for heterogeneity in carriers' environmental awareness.
The mechanism is general: one emissions limit produces a menu of compliance routes, and the route depends on vessel type, trading pattern, owner profile and prevailing prices. Scrubbers, compliant fuel, alternative fuel and efficiency measures are substitutes at the level of compliance and complements at the level of the ship, so a uniform rule produces a non-uniform equipment mix. That is cost and constraint, not attitude, and it explains why equipment demand after a regulatory shock never lands in one product category.
Retrofits: calculated versus measured
Existing tonnage must comply with rules written for new designs, and much of that compliance turns out to be operational. Lee, 2026 assesses EEXI and CII compliance across existing container ships. EEXI compliance relied mainly on engine-power limitation measures such as EPL/ShaPoLi, delivering an average calculated CO2 reduction of about 17.3% while calculated speed fell about 10%. The actual CO2 reduction based on DCS data for CII calculation was about 33.6%, with speed down about 39%. Propeller retrofits reduced required shaft power without sacrificing speed, most markedly in vessels above the 6,000 TEU class, and the deterioration in CII rating slowed afterwards. The author notes limits: the measure is not suitable for all ships and is an interim step.
The gap between the calculated and the measured numbers is the analytically important part. Engine-power limitation changes what the engine is permitted to deliver; what the ship actually emits depends on how it is operated, which is why DCS data produces a different figure from a design calculation. Monitoring, data acquisition and voyage-level measurement therefore sit inside the compliance pathway. A fleet that cannot measure its own performance cannot demonstrate improvement, and measurement capability becomes a specification item in its own right.
Adoption follows structure, not enthusiasm
Adoption is stratified by firm characteristics. Mäkitie et al., 2022 analyse a survey of 281 shipowners in Norway, a major ship-owning country and centre for maritime technology development, distinguishing actual from intended adoption of alternative fuels. Early adopters were large and established owners in offshore, international cargo and domestic passenger shipping, often subject to specific contractual demands for alternative-fuel adoption. Laggards were typically small and young owners operating where such demands are weak; business strategy and financial and knowledge resources may also matter.
Read as industry structure, this is predictive. Alternative-fuel demand should cluster in segments with creditworthy counterparties and contractual pressure, and equipment for those projects will be specified earlier and to a higher standard. The retrofit market for the wider fleet will be driven by compliance minima instead — a different product mix, with different tolerances, service expectations and lead times.
Shore power shows the trade-offs
Electrification at berth is the clearest case where a green measure is not unambiguously green. Lathwal, Vaishnav and Morgan, 2021 use government data for all major ports in India: switching berthed ships from high-sulphur fuel to shore power cuts hoteling (at-berth) emissions of PM2.5 by 88%, SO2 by 39% and NOx by 85%, but raises CO2 by 12%. Switching from low-sulphur fuel cuts PM2.5 by 46% and NOx by 84%, but raises SO2 by 240% and CO2 by 17%. Lifetime cost savings from the switch are estimated at $73 million for high-sulphur fuel and $370 million for low-sulphur fuel. The health effect is conditional: the high-sulphur switch might avoid at most a couple of dozen premature deaths a year, while the low-sulphur switch could slightly increase premature mortality, so the authors stress cleaning up power generation first.
Shore power moves emissions from the ship's stack to the grid, so its net effect depends on the local generation mix, the fuel displaced and the relative value of local air quality and global carbon. For equipment, a shore-power specification is a system — cable management, connection hardware, transformers, switchgear and onboard distribution sized for the load — and its economics depend on how long the ship is actually at berth.
What pulls through into marine equipment
The evidence makes the equipment consequences concrete. A fleet operated for carbon intensity rather than delivery alone has different duty cycles: slower steaming, longer periods at anchor and in port, more attention to just-in-time arrival. Those alter the load profile of deck and mooring equipment, including mooring winches, because mooring and anchoring gear are sized around operating patterns. A change in pattern is a change in the specification envelope even when the ship itself is unchanged.
Deck equipment is also a site of abatement. Chica, Hermann and Lin, 2023 model fleet retrofits of wind-assisted propulsion technologies and note that deck equipment, including wind propulsion, offers the largest potential fuel savings among energy-saving technologies. Their agent-based simulation finds adoption sensitive to subsidies, fuel prices and networking, and that product-service business models can lower introduction barriers. Wind assistance is a deck-machinery and structural project — foundations, load paths, control systems, operating procedures — so its diffusion drives deck-engineering demand.
Electrical and monitoring content grows for a different reason. Power limitation is implemented through control systems; CII and EEXI compliance depends on DCS data; shore power requires an electrical interface; fuel conversion changes what must be monitored in the engine room. The direction of travel is more sensors, more integration and more data handling per vessel.
Safety follows. Alternative fuels differ from conventional marine fuel in flammability, toxicity and storage conditions, which changes the hazard basis for gas detection, ventilation, fire protection and safety equipment such as life-saving appliances. A two-speed fleet therefore has two safety baselines: newbuildings designed around one fuel's hazards, and existing ships whose systems were specified for another fuel and must be adapted on conversion. That adaptation is engineering work with a real equipment bill attached.
The transition as an equipment cycle
The empirical record supports a narrower conclusion than the policy debate usually offers. The transition is not a single future event; it is a present-tense, uneven process, priced in secondhand values, engineered through retrofits, measured through operational data and adopted along existing lines of firm size, segment and contract. The orderbook shows the next generation of ships; the active fleet shows what must be retrofitted, re-specified and monitored in the meantime.
For marine equipment, demand is driven less by a general green premium than by specific compliance pathways: power limitation and propeller retrofits pull through propulsion and control content; carbon-intensity management pulls through monitoring and data acquisition; wind assistance pulls through deck structures and machinery; fuel conversion pulls through safety and hazard systems; shore power pulls through electrical interfaces. The two-speed fleet is not a temporary anomaly to be resolved by one technology. It is the structure of the market that equipment supply already serves.
References
- International Maritime Organization. 2023. 2023 IMO Strategy on Reduction of GHG Emissions from Ships. International Maritime Organization. imo.org
- United Nations Conference on Trade and Development. 2025. Review of Maritime Transport 2025 (Overview). UNCTAD. unctad.org
- Lu, P.-H., & Theocharis, D. 2025. The influence of energy efficiency and carbon indicators on ship prices: early evidence from the tanker and bulk carrier sectors. Maritime Economics & Logistics, 27(3), 549–566. https://doi.org/10.1057/s41278-025-00316-5
- Bai, X., Hou, Y., & Yang, D. 2021. Choose clean energy or green technology? Empirical evidence from global ships. Transportation Research Part E: Logistics and Transportation Review, 151, 102364. https://doi.org/10.1016/j.tre.2021.102364
- Lee, S.-S. 2026. EEXI compliance and CII performance in existing container ships: Implications for propeller retrofit. Applied Ocean Research, 174, 105214. https://doi.org/10.1016/j.apor.2026.105214
- Mäkitie, T., Steen, M., Saether, E. A., Bjørgum, Ø., & Poulsen, R. T. 2022. Norwegian ship-owners' adoption of alternative fuels. Energy Policy, 163, 112869. https://doi.org/10.1016/j.enpol.2022.112869
- Lathwal, P., Vaishnav, P., & Morgan, M. G. 2021. Environmental and health consequences of shore power for vessels calling at major ports in India. Environmental Research Letters, 16(6), 064042. https://doi.org/10.1088/1748-9326/abfd5b
- Chica, M., Hermann, R. R., & Lin, N. 2023. Adopting different wind-assisted ship propulsion technologies as fleet retrofit: An agent-based modeling approach. Technological Forecasting and Social Change, 192, 122559. https://doi.org/10.1016/j.techfore.2023.122559
