is stored in the ship's recovery tanks. During crisis time the ship, capable of carrying 1,000 tons of fuel and 100 tons of cargo, can be armed with one 40 mm main gun, two 12.7 mm machine guns and naval mines, and used to supply island forts and other naval vessels. Design General characteristics Louhi is long, wide and has a draught of . At 3,450 tons, it is the largest ship by displacement currently in service in the Finnish Navy and the third largest ever, second only to the coastal defence ships Väinämöinen and Ilmarinen. The ship is built according to Germanischer Lloyd rules for classification with class notation of GL 100 A5, E4, NAV-OC, Tug, Supply Vessel, Marine Pollution Response Vessel, Oil Recovery Vessel, Chemical Recovery Vessel for the ship and GL MC, E4, AUT, FF1 for the machinery. The vessel is built to the highest Finnish-Swedish ice class, 1A Super, with special consideration for the dimensioning of the propulsion and hull to meet the requirements for icebreaking capability as the Finnish-Swedish ice class rules do not extend to icebreaking vessels. Power and propulsion Electricity is produced by four 9-cylinder Wärtsilä 9L20 4-stroke medium-speed diesel generating sets with a combined output of . The generators provide power for all shipboard consumers, including two 2,700 kW Z-drive thrusters with 3.1-metre () four-bladed propellers and a 500 kW bow thruster. The diesel-electric azimuth thrusters, manufactured by Rolls-Royce, give the vessel excellent maneuverability at low speeds, stationkeeping and dynamic positioning capability, and a towing capacity of . Louhi has icebreaking capabilities second only to real icebreakers. The ship is designed to maintain a continuous speed of in ice and in ice, both with a snow cover. Additionally the vessel is designed to be capable of penetrating an ice ridge with a maximum thickness of with a single ram starting from , maintain a speed of in thick brash ice channel and be capable of operating in brash ice channels up to thick. In open water the ship has a service speed of . The operational range of the vessel is and the provisions give the ship an endurance of 20 days. Recovery equipment The mechanical oil recovery equipment on board Louhi is based on the same stiff brush technology that has been proved to be effective by the previous Finnish spill response vessels. The vessel is equipped with three different types