Maersk to test 35 metre rotor sail on 8,700 TEU container ship

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A.P. Moller Maersk will test wind assisted propulsion on one of its 8,700 TEU container ships after selecting Anemoi Marine Technologies to supply a 35 metre Rotor Sail, taking technology already deployed on bulk carriers into the container shipping sector.

The fixed Rotor Sail is scheduled for installation in mid 2027 and will be tested during normal commercial operations, with the vessel expected to operate on North and South Atlantic routes.

The project is intended to determine how much wind assisted propulsion can reduce fuel consumption and emissions on container ships, where available deck space and cargo operations create different constraints from bulk carriers and tankers.

Under the agreement, Anemoi will design, manufacture and deliver one Rotor Sail measuring 5 metres in diameter and 35 metres in height.

The equipment will be installed on a vessel in Maersk’s 8,700 TEU Maersk Lima class and integrated with existing onboard systems. Anemoi will also provide engineering and installation support.

Unlike conventional sails, Rotor Sails are powered rotating cylinders. Wind passing around the spinning cylinder creates a pressure difference through the Magnus effect, producing additional thrust that can reduce the amount of propulsion power required from the vessel’s main engine.

Container ships present a particular challenge because much of their deck area is required for containers. Anemoi Chief Commercial Officer Nick Contopoulos told the Financial Times that predictable liner routes could, however, strengthen the case for wind propulsion because operators can assess prevailing wind conditions against vessel speeds and voyage patterns.

Maersk is treating the installation as a pilot rather than committing to broader fleet deployment.

Ole Graa Jakobsen, Maersk’s head of fleet technology, said wind assisted propulsion was among several technologies being considered to improve vessel efficiency and reduce emissions.

The company expects the trial to provide practical operating experience and help determine whether Rotor Sails could have a wider role across its fleet.

That assessment will be closely watched because wind propulsion has so far gained more commercial traction on bulk carriers, ore carriers and tankers than on container vessels.

Anemoi has already installed its technology on several large bulk ships. Five 35 metre Rotor Sails were installed aboard the 400,000 dwt ore carrier Sohar Max in 2024, with projected fuel savings of up to 6% and annual carbon reductions of as much as 3,000 tonnes.

Its 5 metre by 35 metre Rotor Sail design also holds DNV type approval for wind assisted propulsion systems.

The Maersk trial comes as shipowners face increasing pressure to improve vessel efficiency while managing fuel and carbon compliance costs.

Industry estimates suggest wind assisted propulsion can deliver fuel savings ranging from about 5% to 25%, depending heavily on vessel design, operating speed, route and wind conditions. Anemoi estimates an individual Rotor Sail can save roughly one tonne of fuel and three tonnes of CO2 per day, although actual performance varies by deployment.

For container operators, the question will therefore be straightforward: can the fuel and emissions savings compensate for the installation cost, additional equipment and loss of usable deck space?

The Maersk installation should begin providing that answer when the 8,700 TEU vessel enters commercial trials in 2027.