Full sail ahead for Rotor Sails

Oct 31, 2023 | Featured Article, Opinion

With vessel efficiency front and centre following the IMO’s recent MEPC 80 session, shipowners and managers are turning to Rotor Sails during scheduled berthing and drydocking to reduce their emissions and fuel consumption.

With decarbonisation efforts high on the agenda for the global shipping industry, modern cargo vessels are looking to become energy efficient, with current efforts tied closely to the goal-based and technology-neutral regulations of the International Maritime Organization (IMO).

The IMO’s 80th meeting of its Marine Environmental Protection Committee (MEPC 80), which took place in July, brought the topic of vessel efficiency centre stage. Amidst a renewed commitment to reducing the maritime sector’s carbon emissions was an aim to review and strengthen the energy efficiency design requirements for ships, including the regulations by which a vessel’s energy efficiency is measured, mainly the Carbon Intensity Indicator (CII) and the Energy Efficiency Existing Ship Index (EEXI).

In a bid to meet the IMO’s goal of achieving net-zero by or around 2050, the uptake of low and zero-carbon technologies that can significantly reduce a vessel’s carbon footprint and speed up global decarbonisation efforts has picked up pace by shipowners looking for viable alternative propulsion options.

With wind energy in plentiful supply across most trading routes, shipowners are taking a page from their history books to fit sails onto their vessels. However, long gone are the days of traditional sails. Modern sails for today’s fleet, known as Flettner Rotors or Rotor Sails, are technologically advanced and mechanically capable of providing sufficient auxiliary propulsion to enable a vessel to reduce its burden on engines and cut its carbon emissions significantly.

Crucially, Rotor Sails have already proved popular for shipowners looking for energy-saving technologies that can be easily retrofitted onto existing vessels that are at berth or in drydock.

Anemoi retrofitted three 24m-tall Rotor Sails on board the 82,000dwt Kamsarmax bulk carrier TR Lady in Chengxi Shipyard in China

Anemoi retrofitted three 24m-tall Rotor Sails on board the 82,000dwt Kamsarmax bulk carrier TR Lady in Chengxi Shipyard in China


The technology behind Rotor Sails is incredibly simple. It relies on an aerodynamic phenomenon, known as the Magnus Effect. As the cylinder rotates within an airflow, a forward thrust force perpendicular to the apparent wind direction is created, delivering additional thrust to the vessel. This thrust can either increase vessel speed or maintain vessel speed and reduce power from the main engine. Either way, a vessel’s fuel consumption can be minimised and, crucially, its emissions output drastically cut.

Rotor Sails are suitable for almost all types of vessel. Their varying designs and installation methods mean they can be installed on bulk carriers, tankers, ferries, RoRo and multipurpose vessels.

Each Rotor Sail can be installed in a single crane lift and connected to the foundation of the ship’s main deck in less than a day. Notably, compared to other technologies, the technology is considered a movable asset whereby the sails can be transferred to another vessel as driven by owner’s requirements.

This simplicity in design and installation has made Rotor Sails an ideal choice for quick and effective retrofitting projects for a vessel during drydock. In addition, installation projects have been carried out when a vessel is at berth, thanks to the speed and simplicity of the installation process.


Read more in the latest issue of DryDock magazine