Vessel design approval simplifies Rotor Sail integration on medium-range tankers

Anemoi Marine Technologies (‘Anemoi’) and several industry partners have concluded a joint development project (JDP) that integrates Anemoi’s Rotor Sails - comprising two folding, EX‑rated units - into the design of a medium-range (MR) tanker – simplifying selection and installation of the technology.

The design was developed with Guangzhou Shipyard International (GSI) and ship operator Hafnia. Classification society DNV, reviewed the rotor sail integration for the vessel and has now issued an Approval in Principle (AiP) for the design. As part of the project, the partners addressed the technical, structural, operational and regulatory demands of deploying Rotor Sails in the MR tanker segment, which faces tight constraints around deck space, cargo operations and safety.

The completed concept uses an EX-rated version of Anemoi's 5x35m folding Rotor Sail, meeting the explosion safety requirements for equipment in the hazardous areas on product tanker decks. Working with GSI, Anemoi developed a lightweight deck seat that does not require underdeck strengthening while still allowing straightforward inspection and long-term maintenance.

As well as providing owners with a verified basis on which to take the design forward, the project also demonstrated significant potential benefits to the vessel's energy efficiency performance. DNV reviewed the design package, including the treatment of the Rotor Sails within IMO’s EEDI and EEXI framework, accounting for potential interactions between the sails, before issuing the AiP.

The AiP helps to smooth the adoption of Rotor Sails in MR tankers while adding to the growing commercial confidence in wind-assisted propulsion across the wider tanker sector. This milestone also further reinforces Anemoi's position as the integration partner of choice across an expanding range of vessel types.

The achievement was marked with a ceremony during the Posidonia 2026 exhibition in Athens, which took place from 1–5 June.

Nick Contopoulos Chief Production and Partnerships Officer, Anemoi shared "Completing this project is a significant step for wind-assisted propulsion in the tanker sector. Demonstrating that our EX-rated Rotor Sail can be integrated efficiently, safely and with minimal structural impact on MR tankers gives owners a clear, verified pathway to adoption. We are grateful to all partners for the rigour and commitment they have brought to this work."

Jesper Kristiansen, General Manager Technical, Hafnia shared "Identifying practical, scalable efficiency measures for the MR tanker segment is a priority for Hafnia as we navigate increasing energy efficiency and emissions reduction demands from both charterers and regulators. The work undertaken with Anemoi, GSI and DNV gives us a credible technical foundation from which to assess deployment of wind-assisted propulsion across this fleet."

Huang Jun, Deputy Chief Engineer, Guangzhou Shipyard International shared "This project not only deepens industry understanding around wind-assisted propulsion integration but also solves very practical issues to deploying solutions on MR tankers. The result is that we are now in a position to offer Rotor Sail–ready MR tanker designs to owners worldwide."

Aakash Dua, Regional Business Development Manager at DNV, shared: "The technical challenges of the integrating new on deck efficiency solution for MR tanker make having an independent verification of new designs essential. At DNV we are continually working to have our WAPS rules and guidelines to evolve as innovations hit the market, building confidence and letting owners take advantage of new solutions. Working together with GSI, Anemoi and Hafnia, this AiP means we have a new technical reference point for WAPS in this important ship segment.