Wind propulsion technology could deliver fuel savings of up to 9.2% on expedition cruise vessels, according to a case study conducted by Wallenius Marine and Salén Ship Management.

The study, carried out within the EU-funded Orcelle Horizon project, examined how wing sails could be adapted for cruise operations, which differ markedly from the cargo shipping sector where wind-assisted propulsion is more commonly discussed.

Using operational data from the expedition cruise vessel Hebridean Sky—including its schedule, routes, service speeds and prevailing winds—the team simulated power, fuel and emission savings over a full year of operation.

The analysis found the highest gains in Nordic waters, with the lowest savings recorded in the Mediterranean and Indian Ocean regions.

"Although we are used to slightly higher percentage savings on wind-assisted cargo vessels, 9% is a significant number in shipping," said Lukas Blau, Design Manager and Naval Architect at Wallenius Marine.

Operational challenges

The study highlighted key differences between cargo and cruise vessel operations. Cargo ships typically sail for extended periods between ports, while Salén's cruise vessels spend approximately 50% of their time in port or at anchor, visiting one or two locations daily.

"Cargo vessels sail for days or weeks until they reach the next port and then leave as soon as the cargo is on board. Salén's cruise ships spend about 50% of their time in ports or at anchor," Blau explained.

Deck space presents another constraint. While pure car and truck carriers can accommodate large wing sails on open upper decks, cruise ships require this area for passenger amenities and recreational facilities.

Anders Karlsson, Technical Director at Salén Ship Management, commented: "I was surprised to see that wind offered benefits even on our shortest legs—even when sailing around Sicily."

Alternative fuels examined

The study also evaluated alternative fuel options, with biodiesel and green methanol identified as the most realistic choices for the cruise segment.

Katarina Salén, CEO of Salén Ship Management, said the collaboration provided unexpected insights: "I first came across wing sails when I saw an image of them at the Wallenius Marine office, and I was instantly fascinated. After speaking with their engineers, they came back to me with the idea of doing a case study—something I never expected."

She added that expedition travellers, who are typically nature-oriented, would likely welcome wing sails on board, noting that sails align with the classical yacht aesthetic of Salén's vessels.

Broader applications

Wallenius Marine is applying insights from the cruise study to its Sleipner RoRo concept, a wind-assisted vessel designed for transatlantic car and cargo transport. The company is also conducting research on short-sea RoRo vessels.

"Our mission is to find solutions that contribute to more sustainable shipping. It's the right thing to do — and soon, those who don't adapt will be left behind," Blau said.

The Sleipner RoRo design includes preparations for wing sails, shore power, and alternative energy sources including batteries and fuel cells.

Wallenius Marine's wind propulsion work forms the basis for Oceanbird, a wing-sail concept that the company says is not limited to specific vessel types.