The large-ship wind-assisted fleet passed 100 vessels in 2026, with IWSA reporting 116 ships in service and around 100 more units on order at SMM in September 2026. Class-assessed results from Bureau Veritas and DNV put annual fuel savings at roughly 5-15% per ship, while peak-voyage figures of 20-37% are not annual averages.
What it is and how it works
Wind-assisted ship propulsion keeps the main engine and adds thrust from the apparent wind. Four hardware families dominate. Flettner rotor sails spin a vertical cylinder so that the Magnus effect produces lift at right angles to the wind. Suction wings, such as the bound4blue eSAIL and the Econowind VentoFoil, use fans to draw boundary-layer air through a perforated surface, which delays stall and multiplies lift from a small chord. Rigid wing sails, including the WindWings from BAR Technologies and the Oceanbird Wing 560, are automatically trimmed aerofoils. Kites such as the Airseas Seawing fly at altitude and tow the ship through a tether. Because every system is an assist, savings depend on route wind statistics, service speed and whether the operator sails slower or simply burns less fuel at the same speed.
Why it matters now
The fleet count has moved quickly. IWSA counted 37 wind-powered and 11 wind-ready ships in 2024 (Offshore Energy), 70 large vessels in mid-2025 with about 130 more on order, and more than 100 ships with over 230 systems installed by June 2026 (IWSA). At SMM Hamburg in September 2026 the association reported 116 vessels in service, 12 ready to enter service and around 100 further units on order (Boaton). DNV says the fleet has grown fivefold since 2022. Bulk carriers and tankers lead uptake. IWSA is a trade association whose members sell the technology, and counts differ between sources because definitions of installed, wind-ready and on-order ships vary.
Key players and products
Norsepower reported 32 rotor sails on 18 ships in service in March 2025 and opened the first dedicated rotor sail factory in Dafeng, China, in late 2024, with capacity of 50 units a year rising to 100 by the end of 2027. Anemoi completed five rotor sails on Vale's 400,000 dwt ore carrier Sohar Max in October 2024, designed for up to 6% fuel reduction. BAR Technologies had 13 WindWings fitted across five Union Maritime vessels by May 2026 and signed an MoU with HD Hyundai Heavy Industries in June 2026 (Hellenic Shipping News). Econowind had sold more than 150 VentoFoil units by July 2026 and holds DNV type approval for its 3-Series. Oceanbird, the Wallenius and Alfa Laval venture, installed its first Wing 560 on the Wallenius Wilhelmsen car carrier Tirranna in June 2026 (Oceanbird).
Figures that matter
| Metric | Value | Source type | Source |
|---|---|---|---|
| Ships in service, September 2026 | 116, with around 100 units on order | aggregator | IWSA via Boaton |
| Three eSAILs on Ville de Bordeaux | 568 t fuel/yr, 1.7 t/day average | verified | Bureau Veritas |
| Pyxis Ocean, two WindWings, six months | 3 t/day, about 14% | trade-press | Cargill/BAR via BusinessWire |
| 25 rotor sail installations, typical saving | 4-15%, 3-6 year payback | verified | Sustainability journal |
| Sohar Max design target | up to 6% | vendor | Anemoi |
| Single Wing 560 | up to 10% | vendor | Oceanbird |
| Cost of a 2-3 rotor installation | EUR 1-2 million | aggregator | CORDIS |
The Bureau Veritas assessment of three eSAILs on the LDA ro-ro Ville de Bordeaux is the clearest independent datapoint: 568 t of fuel and 2,181 t of CO2 saved per year, measured without weather routing (Bureau Veritas). Cargill's Kamsarmax Pyxis Ocean averaged 3 t/day, about 14%, over six months with two WindWings, exceeding 11 t/day in optimal conditions, with DNV engaged as independent verifier (BusinessWire). A 2025 study of 25 confirmed rotor installations found typical savings of 4-15% and a 3-6 year payback once carbon costs are included (Sustainability). Syroco's digital-twin evaluation of the rotor-sail tanker Alcyone confirmed up to 21% per voyage with wind and routing combined. Oceanbird's claim of up to 10% from a single wing awaits third-party verification in autumn 2026, and the EUR 1-2 million installation cost comes from older EU material published by CORDIS.
Developments 2023-2026
- 2023-24: Pyxis Ocean retrofitted with two WindWings at COSCO Shanghai; Anemoi completes Sohar Max; Norsepower opens the Dafeng factory.
- 2025: Bureau Veritas verifies the eSAIL savings on Ville de Bordeaux; Norsepower books six GEFO tankers and the three-ship Airbus ro-ro order; BAR wins its first LR2 tanker WindWings order; bound4blue fits its largest eSAILs on the LDC juice carrier Atlantic Orchard.
- 2026: IWSA announces the 100-vessel milestone; Oceanbird fits the Wing 560 to Tirranna; BAR signs with HD Hyundai Heavy Industries; Econowind gains DNV type approval and launches a 5-Series for deep-sea ships; bound4blue fits four 22 m eSAILs on Marflet Marine's Santiago I (Cyprus Shipping News).
Outlook
With roughly 100 units on order against 116 ships in service, the fleet could double by 2028, concentrated in bulkers, tankers and ro-ro tonnage. Oceanbird's first two-wing installation, on the car carrier Way Forward, is due in 2027. For fleet planning, the defensible band is a 5-15% annual average; figures of 20-37% describe favourable single voyages.
