Getting to zero was never going to be easy but it was the challenge set for Carl Fagergren, project manager at Wallenius Marine, when he joined the company in 2009.

Having recognised that wind power would play an important role in emissions reduction, Wallenius Marine and its joint venture partner, Alfa Laval, completed the fitting of a single Oceanbird Wing560 to the 2009-built, 30,000dwt Wallenius Wilhelmsen car carrier Tirranna in June this year.

Tirranna is the test bed for Oceanbird, but even before the Wing560 installation on the Wallenius ship was completed, the company had its first commercial order for two wing sails to be retrofitted for an undisclosed owner on a yet to be announced vessel type.

“It proves that wind propulsion is not just a concept – it’s a viable, scalable solution for sustainable shipping,” commented Amrit Kaur Bhullar, Oceanbird CEO.

The installation of the Oceanbird wing on Tirranna will provide data that will inform the next stage of development for vessels fitted with wing sails by the time the project ends in December 2027.

The company already expects Tirranna’s single sail to cut emissions on optimal routes by between 7% and 10%, with greater efficiencies with each added sail, although the vessel type and the ship’s trading region will also play a part.

It is also known that any new vessel design will need larger rudders as the ship will no longer have a flow of water from the propeller to help the vessel respond to the rudder control and will need to compensate for yaw caused by wing sails.

In addition, each complete sail unit weighs around 100tonnes and is 46m-high including the mounting and foundation, requiring a greater beam to compensate for heeling moments.

Moreover, the wings can generate a side force causing the vessel to drift. To prevent drift the hull design must be deeper, with a sharper V-shape, and a keel or fins for better course keeping. Nevertheless, Bhullar acknowledged that the installation, “is a pivotal moment for us…so we can prove the value of our efforts.”

“It's very important that we make sure that in ocean-going weather, in high winds, this solution is reliable,” said Bhullar, adding that an Oceanbird team were onboard Tirranna when it sailed from Southampton to Halifax in Canada. “And in that voyage, we successfully tested the reliability of the solution together with the crew onboard.”

Even after the testing, it is a given each retrofitted vessel will need careful design consideration for stability and manoeuvrability, “So there's a limitation on retrofitting effectively,” conceded Fagergren.

Moreover, managing the complex operation for setting each wing, the relationship between the wings, and then an integrated system that controls the rudder, the attitude of the ship and the engine “a sort of sailing brain,” will be required noted Fagergren.

Oceanbird and Wallenius Marine are working with a French digital systems company to develop the necessary software, a seafarer tool of the future to operate wind-powered vessels safely and efficiently.

Installing the Oceanbird Wing560 on Tirranna represents the mid-point of a journey that began 17 years ago and is destined to culminate in a vessel with sail as its primary source of power.

“In 2009, we designed the first sailing car carrier. It was a concept design, and then, we worked with it [and developed it] more actively from 2017 and in 2020 we presented a vessel concept, which was a sailing car carrier that eventually became Orcelle [the concept ship in an EU-funded research project].”

The goal for the concept vessel, which had six sails, was to achieve a 90% cut in emissions, “but that would require much lower speeds and [to operate] in certain areas where there is a lot of wind, such as the North Atlantic,” noted Fagergren.

Since January 2023, Wallenius Marine has worked with its 10 partners in the Orcelle Horizon project, a project that is looking to change wind propulsion for deep-sea shipping from a secondary source of energy to a primary source of power.

A design has already completed, said Fagergren but the next step towards that goal is to test the system onboard Tirranna.

Partners in Orcelle Horizon include StormGeo, DNV, Wallenius Wilhelmsen, RISE, as well as Athens and Gent technical universities, along with AlfaWall Oceanbird, the joint venture between Alfa Laval and Wallenius, which is responsible for producing the Oceanbird Wing560 rigid sail.