In development

ECO ROTOR SAIL

Vessel-specific wind-assisted propulsion, engineered from first principles

A next generation vessel-specific Flettner-rotor energy-saving device with an aerodynamic tail, optimised by full CFD for the host ship rather than supplied as a generic tower. It represents a fundamental evolution of the traditional Flettner rotor by incorporating and engineered aerodynamic tail appendage downstream of the rotating cylinder.

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Why Eco Rotor Sail is different

Bespoke for each vessel

The Eco Rotor Sail is engineered the other way around: the geometry, tail, gap and operating envelope are optimised against the specific ship's hull, superstructure, route wind statistics and operational profile. The result is a smaller, better-matched device for the same delivered fuel saving, or a higher saving for the same footprint.

Magnus-effect rotor with engineered tail

The tail re-shapes the wake and biases the lift vector toward the ship's longitudinal axis, increasing the proportion of force that becomes useful thrust rather than side force.

Built around verifiable measurement

Performance and savings claims will be defined and reported using ISO 19030 / ISO 15016 thinking from day one, so any pilot output is auditable

Retrofit-oriented concept

Designed for practical integration on existing vessels with minimal deck modification.

Key advantages

Higher Efficiency: CFD studies show up to 10% higher thrust and ~5% lower torque compared to conventional rotors under similar conditions.
Route-Robust Performance: Maintains positive auxiliary thrust over a wider range of apparent wind angles, making it more effective across real voyage profiles.
Reduced Environmental Impact: Supports IMO EEXI/CII compliance and EU ETS/FuelEU Maritime requirements through measurable fuel and emissions savings.

Validation status

  • Aerodynamic CFD (2D)
    • Completed 5,110 design points across rotor angle, tip distance, flap angle and apparent wind direction; clean Magnus-type polar with peak at beam reach.
  • Full-scale CFD (3D)
    • Completed 2,242 design points coupling the rotor and tail with a representative ship hull; tail-angle and tip-distance sensitivities mapped.
  • Patent
    • UK patent application filed.
  • Class engagement
    • Independent technical review and class engagement to be opened with the right partner.
  • Pilot installation
    • Vessel-specific design tooling ready to apply to a candidate vessel.

Our design approach

Designed for practical integration on existing vessels with minimal deck modification.

  • vessel performance review
  • wake field assessment
  • axial and tangential inflow characterisation
  • bespoke rotor tail section and wind angle optimisation
  • installation and retrofit assessment

Each Eco Rotor Sail concept is intended to be developed using a vessel-specific workflow that may include:

Suitable applications

Useful for bulk carriers, tankers, ro-ro and general cargo on routes with sustained beam-reach winds. Performance peaks at apparent wind 80–100° from the bow.

Technical information

As Eco Rotor Sail is currently under development, performance claims should remain subject to further design maturation and validation. EcoNavis’ approach is to develop each concept around the vessel’s operational profile and propulsion arrangement rather than relying on standardised rotor geometry.

2D study – sectional aerodynamic polar

  • Performance peaks at apparent flow 80–100°
  • Tip distance is the single most material 2D lever
  • Rotor angle and flap angle are second-order
  • Head-wind penalty is small

3D study – ship-mounted rotor + tail

  • Tail angle dominates ship-frame thrust
  • Rotor rotation (azimuth/yaw) optimum is 10–40°
  • Larger tip distance helps
  • Rotor angle 10–40° plateau
  • 52% of all 3D designs improve on baseline ship thrust
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