The Naval Architect: March 2018
The 13-deck, 63,000gt, 2,800-passenger capacity Viking Line ferry is currently under construction at Xiamen shipyard, China. While electric, azimuthing propulsors have been used on cruise ships since the late 1990s, the Viking Line newbuilding is one of very few such installations on ferries.
The yet-unnamed vessel, due for delivery in 2020, is the third newbuilding of the Mariehamn-based company since 2000. The first, the 35,778gt Viking XPRS was delivered in 2008 and fitted with a traditional medium-speed diesel power plant that drives two controllable pitch propellers via gearboxes and shafts. The four diesels deliver a total of 40,000kW to give the ship a cruising speed of 25knots, which was deemed necessary to reduce the crossing time between the Finnish and Estonian capitals to around two and a half hours.
Viking Grace, much larger at 57,565gt, entered service on the Turku-Mariehamn-Stockholm service in 2013. The ship has four dual fuel Wärtsilä main engines that deliver 30,400kW and drive two propellers via electric motors. In practice, the ship has used LNG, making it the first large ferry to use this type of fuel.
Ulf Hagström, SVP Marine Operations and Newbuildings at Viking Line, told The Naval Architect that with the new ship, the company wants to take efficiency to the next level. To be used on the same Turku-Mariehamn-Stockholm service as Viking Grace, the ship will only spend about three hours in port each day. The superior manoeuvrability that Azipods offer means that time can be saved in docking and undocking. This translates to a lower speed requirement at sea and savings in installed power requirement and fuel consumption.
ABB will supply the twin Azipod XO 2100-type units, with a combined power of 22,400kW. The ship will have a very large wind surface area, and the powerful thrusters are intended to ensure good handling of the ship while manoeuvring in port. The new ship will also be fitted with three bow thrusters from Wärtsilä with electrical motors.
The 218m length of the new ship, five metres more than that of Viking Grace, also requires good manoeuverbility as the vessel will operate in the archipelagos of Turku, the Åland Islands and Stockholm, with only some two hours of open sea on each crossing of about 10 hours.
Hagström notes that officers that are used to working on ships that are fitted with Azipods generally prefer these vessels over conventionally driven ones due to their superior handling qualities. “However, it takes a little bit of time to get used to Azipods. Rudder steering is very course-stable, but when you steer with the propellers, you frequently need to adjust the course of the vessel,” he adds.
Marcus Högblom, head of passenger and dry cargo ship segment at ABB, confidently predicts Azipods are likely to be the propulsion solution of choice on future ferries.
The two largest and fastest RoPax ferries in Japan were the first vessels in the world to be equipped with Azipods. Launched in 2004, the ferries have brought huge benefits to their owners, Shin Nihonkai Ferry, including a 20% reduction in fuel consumption compared to the previous vessels. The ferries are faster than their predecessors and can carry 15% more cargo by volume.
“The ferry sector was quiet for quite some time. There was quite a bit of newbuilding activity in the 1990s, but then it turned very quiet, until about the time Viking Grace was built,” Högblom tells The Naval Architect. Many ferry companies are using ageing vessels – the ship Viking Line’s newbuilding will replace dates back to 1989 – so there is a need for more efficient and environmentally friendly ships.
In the Viking Line project, a simulation was carried out showing Viking Grace operating with Azipod propulsion, using a simulator at the Customer Experience Center at ABB. The results delivered by the digital simulation confirmed that the use of Azipods would deliver superior manoeuverbility and reduce fuel consumption and thereby operating expenses, Högblom explains.
Moving on to the larger picture, Högblom says that as all new marine propulsion technologies that are either in development or studied involve electricity, be they batteries or fuel cells etc, and ferry companies are becoming increasingly interested in preparing their vessels for possible later adaptation to new ways of powering them.
