Throughout the marine industry, acceptance of the Wärtsilä 31 and acknowledgement of its benefits came rather quickly. Its reputation was endorsed with a number of orders for newbuild projects being received within a relatively short period of time.
The first of these new vessels was fitted with the Wärtsilä 31 main engines, to enter regular service was the ‘Hammershus’, a 158 metre long RoPax ferry owned by Danish operator Molslinjen. The ferry operates in the Danish waters between the city of Køge in Zealand and Rønne on the island of Bornholm. It can travel at up to 17.7 knots, and its two Wärtsilä 31 main engines run on 10 ppm ultra-low sulphur marine diesel fuel, a fuel choice that complies with the International Maritime Organization’s (IMO) restrictions on the sulphur content of marine fuel which come into force in 2020.
Each of the V8-cylinder engines has an output of 4880 kW at 750 rpm. The V-configuration makes the engine extremely compact in size by virtue of its short length. The Wärtsilä 31 operates with two-stage turbochargers that produce elevated pressures resulting in very high efficiencies, and consequently low fuel consumption.
The ‘Hammershus’ was built at the Rauma Marine Constructions (RMC) shipyard in Finland and was designed specifically for the Køge – Rønne route, with the primary focus on freight traffic. The fuel efficiency, smokeless operation, and low vibration levels enabled by the Wärtsilä 31 engines are a central feature of the ship’s design.