Considering the bigger picture of sustainable shipping, there are numerous issues at play. On the one hand, the shipping industry is becoming more sustainable; look at the Sulphur Emission Control Areas (SECAs) which are in place, and the global sulphur cap that is coming in 2020. On the other hand, some areas of the industry are questioning the pace of change. For example, the 2015 Paris Climate Agreement doesn’t include any reference to the shipping industry. In addition, the subject of CO2 emissions regulations has yet to be agreed upon by the IMO.


Flettner freighter cargo vessel Switijnk Shipping


Wind-assisted general cargo vessel

C-Job Naval Architects has just delivered a concept design to Switijnk Shipping showing that, in order to speed the process of sustainability, some shipping companies are taking the matter into their own hands. The design was for a wind-assisted general cargo vessel, otherwise known as a Flettner Freighter, that is expected to achieve fuel savings of approximately 14 per cent. The 8,500 DWT vessel will be equipped with two Norsepower Rotor Sails that will supplement the main engines – representing an exciting hybrid solution.

Family-owned Switijnk approached C-Job following its involvement in the European Union Interreg project S@IL, for which C-Job developed the earlier design of a 4,500 DWT Flettner Freighter. C-Job designed this smaller vessel with four Rotor Sails. However, after studying the prevailing wind patterns on Switijnk’s proposed sailing routes, C-Job decided to design a new vessel, called the FF8500, with two larger Rotor Sails.

“Our experience from the Project S@IL study showed that Rotor Sails were the most viable choice compared to other wind assisted propulsion systems,” explains C-Job Business Manager Jelle Grijpstra. “And then, together with Finnish Rotor Sail supplier Norsepower, we concluded that two larger Rotor Sails were most effective for this project. This was because these would yield a comparable propulsive force to four smaller units. Also, with two Rotor Sails, one on the bow and one on the stern, there would be no chance of wind shadows affecting performance.”

“The Rotor Sails were chosen for this project because they are easy to use, safe, reasonably quiet, with no need for extra crew, and cheaper in investment compared to other systems. In addition, the effectiveness of Rotor Sails has been successfully proven.”


Flettner freighter cargo vessel Switijnk Shipping


Space for LNG engines

While the subject of the vessel’s main engines has yet to be decided upon, the matter does demonstrate the advantages of C-Job’s clear focus of the bigger picture. “Switijnk has a well-defined vision of sustainable shipping and we are glad to sit down and share our knowledge with them,” says Jelle. “We have an extensive track record of integrating mission equipment, and we have analysed all the options available to help them achieve their ambitions. To this end, we have reserved space for LNG engines; although this will be dependent on LNG bunkering infrastructure along their sailing routes.”


Velocity prediction research

With the concept design of the vessel complete, the next stage of the project will consist of testing at Maritime Research Institute Netherlands (MARIN). The intention of this velocity prediction research is to validate the design and to quantify the fuel savings to be gained. “Once investors are convinced and the financing is arranged, then Switijnk can continue with the process of selecting a shipyard to build the vessel.”



The Magnus effect

Rotor Sails are deck-mounted rotating cylinders that utilise the Magnus effect to create a propulsive thrust. The Magnus effect is a force that acts on a spinning body in a moving airstream. Because the Magnus effect acts perpendicularly to the direction of the airstream, the optimum wind direction for Flettner ships is at 90 degrees to the direction of the sailing.

Video: How the Magnus effect works


About Switijnk Shipping

Switijnk Shipping is a family-owned company with over 100 years of experience in international seafaring. The company operates two 7,600 ton-vessels MS Ameland and MS Skylge (both launched in 2009) with a strategy targeted at maintaining long-term capital instead of short term profits.
As an environmentally conscious company, Switijnk Shipping wants to use the FF8500 Flettner Freighter concept to work towards the sustainable future of freight shipping by leading the field on the subject of wind assisted propulsion.
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