acceleration figures at various locations of the vessel at zero speed. The vessel had to be able to operate at least 80 % of the time in the North Sea in the summer and autumn season plus have a roll period longer than 10 seconds. The solution with narrow breadth in the aftship results in a sufficiently long roll period. At the midship and aft ship area there are also exceptionally wide bilge shelves as an integral part of the hull, to further dampen the rolling. Moreover, the vessel is equipped with a U-shaped semi-active anti-rolling tank across the widest point of the bow section. The good seakeeping characteristics are an asset also in Arctic operations and long transit distances. For offshore construction projects Fennica is equipped with a Hydralift crane capable of lifting 30 tons at a radius of or 15 tons at . She also has a smaller MacGregor crane capable of lifting 5 tons at or 1.5 tons at . The vessel can also be equipped with a 120-ton A-frame for trenching machines and ploughs. Fennica has a helipad and can accommodate 48 workers in addition to the ship's crew. Before her helipad was rebuilt in 2012, she also had a small hangar capable of accommodating one helicopter for ice reconnaissance. Since Fennica acts as an escort icebreaker during the winter season, she is also equipped with a Aquamaster-Rauma anchor handling and towing winch, and stern notch for assisting merchant ships. The oblique bridge maximizes visibility from the starboard side steering position. Power and propulsion Fennica has a diesel-electric propulsion system with four main generators. She has two twelve-cylinder Wärtsilä Vasa 12V32D and two sixteen-cylinder 16V32D four-stroke medium-speed diesel engines driving Strömberg alternators, the former producing and the latter each. The main engines are also equipped with exhaust gas economizers. In late 2011 they were also retrofitted with catalytic converters and urea spraying systems to reduce NOx emissions in order to meet the strict EPA requirements. While designed according to the power plant principle in which the main generators produce power for all shipboard consumers either directly or through a motor-generator, Fennica has one auxiliary diesel generator that can be used to produce electricity when the ship is at port. The four-cylinder Wärtsilä Vasa 4R22 4-stroke medium-speed diesel engine has an output of at 1,000 rpm. In addition she has a twelve-cylinder Caterpillar 3412 DISA emergency diesel