Three large new escort tugs contracted by Norwegian offshore services provider Østensjø Rederi, will feature Wärtsilä dual-fuel (DF) engines integrated with a customized gas storage and supply system also supplied by Wärtsilä. The tugs will operate primarily on LNG (Liquefied Natural Gas) but the Wärtsilä DF engines provide the flexibility to select the most suitable fuel according to availability, price and local environmental restrictions.
The contract for the Wärtsilä solution was signed in December 2014. The design of the tugs has been carried out by the designer Robert Allan Ltd in Canada, in close cooperation with Østensjø Rederi.
The overall LNG system, which incorporates Wärtsilä’s unique LNGPac fuel system, a fully integrated gas handling system, and the Wärtsilä Gas Valve Unit (GVU), has been specially designed by Wärtsilä to accommodate the need for a compact solution. The tugs will be powered by 6-cylinder Wärtsilä 34DF dual-fuel engines. The Wärtsilä equipment will be delivered during the first half of 2016.
“These are trend setting tugs in that they provide environmental sustainability through the use of LNG fuel. Wärtsilä is the technology leader in making this trend possible. At the same time, the flexibility of the dual-fuel engine technology also ensures a high level of operational security since the switch from gas to diesel can be made at any time without loss of speed or power,” says Mr Carl Johan Amundsen, Project Manager at Østensjø Rederi.
The vessels are designed to have a bollard pull of 100 tons, and will operate at Statoil’s Melkøya terminal near Hammerfest, Norway. Wärtsilä and Østensjø have cooperated closely to develop the chosen LNG solution for these new vessels.