Wallenius SOL, the Swedish shipping company that was formed in early 2019, is building up to four LNG powered vessels at the CIMC Raffles shipyard in China that will be the largest ro-ro ships using this fuel.
Two ships have been ordered so far with an option for a further two. The first ship is due to be delivered in August, with the second vessel expected before the end of this year. Both vessels will be used on the company’s service between ports in the Gulf of Bothnia and continental Europe, the requirements of which have significantly affected their design.
The Wallenius SOL newbuildings differ markedly from other recent ro-ro ships due to their high deadweight tonnage, explains Christian Damsgaard, head of naval architecture at Knud E. Hansen, the Danish company
that was in charge of the design of the vessels.
In terms of hull dimensions, the Wallenius SOL newbuildings will have a length of 241.7m and a beam of 35.2m, thus being in the same league as the GG5G ro-ros that Grimaldi group is building for its own brand and Finnlines, its Helsinki based subsidiary. These ships are 238.0m in length and have a 34.0m beam. However, while the Grimaldi ships only have a deadweight tonnage of 17,000, the figure for Wallenius SOL's vessels is about 27,000.
“These ships have been designed to carry very heavy loads, such as export loads of paper, which is very heavy. This again has had a number of implications for other aspects of their design,” Damsgaard tells The Naval Architect.
A key consequence is that the light displacement of the ships should be reduced as much as is viable. Pillars were used inside the vessel to support the four cargo decks, which is not the preferred solution when handling paper. However, in the case of these ships it became a necessary one.
The ships will carry mainly paper on the southbound leg of their voyage, whereas northbound the cargoes will be much lighter. This means that the hydrodynamics of the hulls had to optimised for two levels of draught, with about two metres difference between them (the summer load line will be 8.70m). This has led to optimisation of the propulsion train at varying loads.
They will be built to Finnish/Swedish ice class 1A Super which, together with a high displacement, low added resistance in waves, varying draughts and low delivered power, creates quite challenging requirements for the hull lines. The result is a hull with an ‘ice-friendly’ twin skeg and bulbous bow, all of which was heavily optimised by the use of CFD before it was tested at the towing tank.
The vessels will be fitted with two WinGD 7RT-Flex50DF main engines, each developing 10,080kW and giving them a top speed of 20knots, while their cruising speed will be 16knots. LNG will be stored in two tanks with a capacity of 685m3 each.
Using LNG as fuel will result in a significant drop in emissions – Wallenius SOL puts the figure for greenhouse gases at 63%, that for NOx is at 96% plus the ones for SOx and particulates both at 99% when compared with the 2006 built Tundraland, its newest ship to date.
The new ships will be significantly larger than Tundraland and its two sister vessels that were built in Finland, atwhat is now Rauma Marine Constructions, in 2006-2007.
They have a deadweight tonnage of 15,960 and a length of 190.80m, plus a beam of 26.44m. Lane metre capacity is 2,744 – roughly half of the figure of the newbuildings.
Wallenius SOL is using two of the three Tundraland class vessels on a service that links the ports of Oulu, Kemi, Kokkola and Pietarsaari in Finland with Lubeck, from where the ships proceed to Antwerp and Tilbury before heading north again, with calls at Zeebrugge, Vaasa and Kokkola before repeating the cycle from Oulu.
The rotation takes two weeks to complete and allows the use of these fairly large ships to serve ports that on a stand-alone basis might not justify being included in such a service that has a weekly frequency. Vaasa was added to the rotation in November 2019 to serve e.g. the Wärtsilä diesel engine factory in the city.