• Military Menu                       

• Introduction
• Systems
• Facilities
• Agencies
• Industry
• Operations
• Countries
• Hot Documents
• News
• Reports
• Policy
• Budget
• Congress
• Links

• WMD
• Intelligence
• Homeland Security
• Space

Icebreaker Otso

The Otso and its sister ship Kontio, launched in 1986 and 1987 respectively, replaced three older icebreakers in the Karhu class (the Karhu, Murtaja and Sampo). Because of their cost-efficiency, the blue-and-white Kontio and Otso are normally the first icebreakers to leave Arctia’s Katajanokka base for deployment in the Bay of Bothnia. In early and late winter, they operate as far north as Tornio, moving southward as the ice conditions change and the Urho and Sisu assume responsibility for icebreaking in the Bay of Bothnia.

The Otso was designed with cost-efficiency in mind. The traditional four thrusters were replaced with an air bubbler system installed in the vessel’s bow. Another new feature was a diesel power plant providing alternating current to all functions, down to the thruster engines. Thanks to its machinery and the design of its hull, the Otso has a lower fuel consumption than older and larger icebreakers.

The patented Wärtsilä Air Bubbling System (WABS) onboard Otso and Kontio consists of three compressors with a combined output of 1,900 kW that pump air through 46 nozzles located below the waterline on both sides of the vessel. The importance of reducing friction between an icebreaker's hull and the ice or snow by hull lubrication has been known for a long time and bow screws have been used on ships designed for sub-Arctic conditions. These propellers, however, are at high risk in Arctic conditions and this prompted intensive research in the 1960's at the Oy Wärtsilä Ab Helsinki shipyard to try to find an alternative method for use on icebreakers venturing further north. The idea of using air bubbles to create a lubricating water stream arose from the investigations of the two phase propulsion system, in which the propulsive effect is obtained by mixing gas and liquid, carried out at the Helsinki University of Technology. Model testing and detailed design of the system started immediately, and the first installation was made in 1969 in the roll on roll off ferry MS Finncarrier.

The Kontio is experienced in oil spill preparedness and response. Outside the Baltic icebreaking season, the vessel was in a continuous state of readiness for oil spill response operations in the northern Baltic Sea from 2010 until 2016.

Launched in 1987, the Kontio was designed with particular attention to improved icebreaking efficiency on the Baltic Sea. Thanks to the Kontio’s efficient, twin-thruster hull design and relatively small crew, the vessel’s operating costs are significantly lower compared to previous vessels. The Kontio’s machinery is similar to that of the Otso, an icebreaker launched one year before Kontio.

The Kontio was outfitted with oil recovery equipment in 2010, with funding provided by the European Maritime Safety Agency (EMSA). The oil recovery equipment was supplied by the Finnish company Lamor. The Kontio boasts more than 2,000 m3 of tank volume for recovered oil along with two separate oil recovery systems. This self-powered oil recovery system runs on a dedicated hydraulic power unit. One of the oil collection systems is based on rigid sweeping arms, which float next to the vessel’s hull and guide the oil into the oil recovery system. Either suction pumps or brush skimmers can be attached to the arms to collect the oil.

The tanks for fuel oil are located amidships, as far from the sides of the vessel as possible. This will help minimise the risk of oil spills, should the vessel sustain a gash in the hull as a result of an accident. The Otso’s tanks can hold 1,500 m³ of heavy fuel oil, 340 m³ of diesel oil, and 630 m³ of ballast water for heeling the vessel.

The Otso has four Wärtsilä 16V32 diesel engines, made in Vaasa, with a combined power output of nearly 22 megawatts. Each engine powers a 6,000 V/50 Hz AC generator with a power output of six megawatts. The two rear thrusters are each powered by a dedicated engine, with a shaft power of 2 × 7.5 MW, i.e. 15 megawatts in total.

The shiny band at the waterline of the blue-and-white Otso is a belt made of stainless steel plates, which help to reduce the friction between the hull and the ice. The unpainted belt is two metres in height. Active cathode protection at the junction of steel plates of different chemical composition prevents galvanic corrosion.

Many functions on the Otso can be carried out from the bridge, such as starting, stopping, monitoring the engines and operating the heeling tanks, towing winch and crane, and even hoisting and lowering the flag.

One further innovation was introduced when the Otso was completed – the officers started taking their meals together in the officers’ mess. The previous reform of this kind took place in 1973, when table service on icebreakers was discontinued.