Cycloidal propulsion uses a rotating disc of vertical blades to deliver thrust in any direction almost instantly, which is why Voith Schneider Propellers dominate escort tugs and double-ended ferries. Voith marked 100 years of the design in July 2026, while ABB's Dynafin concept claims up to 22% better efficiency but had no commercial order by late 2025.
What it is and how it works
A cycloidal, or vertical-axis, propulsor rotates a disc carrying vertical blades whose pitch is varied during every revolution. The result is thrust of any magnitude in any direction, changed almost instantly. Ernst Schneider's design was model-tested in 1926 and first fitted to the Torqueo in 1928, and Voith marked 100 years of the Voith Schneider Propeller (VSP) on 6 July 2026 (Voith).
Two electric variants now define the technology. Voith's gearless eVSP replaces the mechanical drive with a permanent-magnet synchronous motor from Voith subsidiary ELIN and uses an eight-bladed rotor intended to run more quietly (Voith eVSP). ABB's Dynafin, unveiled in June 2023, is a trochoidal variant in which a main electric motor turns a large wheel at 30-80 rpm; ABB recommends at least two units per ship and up to four on vessels with a maximum power of 16 MW (ABB).
Why it matters now
The VSP's enduring niche is manoeuvrability rather than efficiency. Voith Water Tractors use the quick thrust response when assisting large ships, double-ended ferries use it to dock without turning, and offshore wind vessels use it for station keeping. Two developments are pulling the concept toward the mainstream. Electrification removes the gearbox and lowers underwater noise, which has brought the eVSP into research vessels and offshore wind service operation vessels. Separately, ABB is attempting to reposition cycloidal motion as a high-efficiency main propulsor for ferries, yachts and mid-size ships, arguing that the motion does not pull air downward and so reduces ventilation at the blade surface (ABB).
Key players and products
Voith is the only established supplier. In July 2024 it delivered VSPs to Egypt for the 1,000th Voith Water Tractor, and in September 2024 Damen Shipyards Group ordered eight VSPs for four hybrid, Robert Allan designed escort and terminal tugs for Boluda Towage, with first deliveries from 2025 (Voith). The Alexandria port authority ordered two further tugs from Timsah Shipbuilding, each with two VSP 28R5/234-2 units for 3,840 kW in total (Professional Mariner). eVSP references include eight units for Ostensjo's four offshore wind vessels, two units for the German research vessel Meteor IV, and the first of three hybrid Port of Hamburg ferries, commissioned in July 2024 with two eVSPs.
ABB's Dynafin programme has no delivered unit. Its partners are Oceanco, which supplied the yacht design tested at MARIN, and a Chalmers University project running from 2024 to 2026 with ABB, RISE and Stena Teknik that is building a method to assess vertical cycloidal propulsors independently (Chalmers).
Figures that matter
The only firm installed-power data are from tug orders. ABB's efficiency numbers are vendor claims from a design study and model tests, not operating data, and the 22% figure comes from an OSK-ShipTech study of a passenger-vessel design (Seatrade Maritime; Interesting Engineering).
| Metric | Value | Source type | Source |
|---|---|---|---|
| Transnet 2014 record order | Nine tugs, each two VSP 32R5/265-2 units of 2,650 kW, 70 t bollard pull | trade-press | Seatrade Maritime |
| Alexandria follow-on tugs | Two VSP 28R5/234-2 units per tug, 3,840 kW total | trade-press | Professional Mariner |
| Dynafin open-water efficiency (claim) | Up to 85% | vendor | ABB |
| Dynafin gain over conventional propeller (claim, OSK-ShipTech design study) | Up to 22% | vendor | ABB |
| Dynafin initial power range per unit | 1-4 MW | trade-press | Interesting Engineering |
| Dynafin wheel speed and installation | 30-80 rpm; two to four units, vessels up to 16 MW | vendor | ABB |
| MARIN tank tests on Oceanco yacht model (claim) | Up to 20% fuel saving | vendor | Oceanco/ABB via Pressmare |
No cumulative VSP delivery count, Voith market share, or independent VSP-versus-azimuth efficiency comparison was found. The Dynafin figures should be read as claims pending the Chalmers assessment and any full-scale trial.
Developments 2023-2026
- June 2023: ABB unveils Dynafin, targeting a full-scale prototype in 2025 and pilot ships in 2025-2026 (Motorship).
- July 2024: VSPs delivered for the 1,000th Voith Water Tractor; first hybrid Port of Hamburg ferry with two eVSPs commissioned.
- September 2024: Damen orders eight VSPs for four hybrid Boluda tugs, deliveries from 2025.
- November 2025: Oceanco and ABB report six months of MARIN tank tests showing up to 20% fuel savings for a yacht model, said to confirm CFD predictions (Pressmare).
- July 2026: Voith marks the VSP centenary, with messaging centred on electric propulsion and low underwater noise.
- No commercial Dynafin order or first installation reported as of late 2025; no 2025-dated VSP or eVSP order surfaced in the research.
Outlook
Cycloidal propulsion will keep its tug and ferry base on manoeuvrability alone, and the eVSP gives it a credible low-noise story for research and offshore wind vessels. Whether the concept becomes a mainstream efficiency propulsor depends on Dynafin moving from tank tests to a pilot ship with measured results, which had not happened by the end of 2025.
