Otso icebreaker

MS Otso is an icebreaking vessel currently owned by the Finnish state-owned company Arctia Oy and operated via the subsidiary Arctia Icebreaking Oy. The 1984-built icebreaker has a same-designed sistership - Kontio (1987-built). Both boats were constructed at Wartsila Helsinki Shipyard in Helsinki Finland.

The vessel (IMO number 8405880) is currently Finland-flagged (MMSI 230252000) and registered in Helsinki.

The shipowner Arctia Oy (2010-founded as Arctia Shipping Oy/since 2016 Arctia Oy) is a state-owned company that operated Finland's icebreaker fleet. The company's divisions/subsidiaries include Arctia Icebreaking (operator of conventional icebreakers), Arctia Offshore (operator of multipurpose icebreakers), Arctia Karhu (port icebreaking services and towing), and Arctia Management Services.

Arctia generally serves Vaylavirasto (FTIA-Finnish Transport Infrastructure Agency/2010-founded government agency responsible for the maintenance of roads, rails and waterways) during winter months. In addition, the company also provides chartered icebreaking services for private companies that operate offshore gas platforms and oilfields, as well as research and drilling companies.

The newest Arctia-owned icebreaking vessels include Fennica (1993), Nordica (1994), Polaris (2016). Arctia's older icebreakers are Sampo (1960), Urho (1975), Sisu (1976).

Otso vessel details and technology

MS Otso was ordered on March 19, 1984, at shipbuilding cost FIM 235 million. The vessel (hull/yard number 472) was launched/floated out on July 12, 1985, and delivered to the Finnish Maritime Administration on January 30, 1986.

Unlike the previous post-war (WW2/1939-45) built Finnish icebreakers, Otso and Kontio's propulsion system is not quad-shaft (2x bow plus 2x aft propellers) but double-shaft - based on 1x bow and 2x aft thrusters (fixed/in-hull mounted, powered by electrical motors).

The hull is coated/painted with "INERTA 160" (two-pack epoxy paint based on liquid epoxy resin). The bow hull plating is ~30 mm (1,2 in) thick. The hull's waterline portion is protected by additional steel plating (stainless, explosion-welded) for reducing ice friction and resisting abrasion. An active cathodic protection system additionally protects from corrosion by making the hull the cathode (of an electrochemical cell) connected to a more easily corroded "sacrificial metal" (acting as the anode).

The hull's friction with the ice is reduced by using an Air Lubrication System (powered by two compressors / combined power output 1,1 MW). Aka "Air Bubbling System", the technology is based on generating a layer of air bubbles (distributed across the hull's entire underwater surface), which results in energy/fuel savings as well as CO2 reduction.

The icebreaking vessel has the following general specifications.

• Hull ice-class: 1A Super (Finland), PC4 (Bureau Veritas)
• Max Draft/Scantling: 8 m / 26 ft
• Min Draft: 7,3 m / 24 ft
• Airdraft: 37 m / 121 ft
• LWL/waterline length: 92,3 m / 303 ft
• Displacement tonnage: 9222 tons
• DWT Deadweight tonnage: 2157 tons (summer DWT: 2000 tons)
• Ice-breaking capacity 1 m
• Bollard pull/emergency pulling or towing capacity: 160 tons
• Ice-heeling/resistance to ice pressure: 1250 m3
• Aft Helideck: 12 m / 39 ft
• Helideck/loading capacity: 2,9 tons
• Fuel storage capacity: 2068 m3 (dual fuel tanks: HFO-Heavy Fuel Oil and DO-Diesel Oil)
• Lubricating oil: 41 m3
• Freshwater tanks capacity: 336 m3
• Water-ballast tanks capacity: 2390 m3
• Freshwater making capability/daily: 9 tons
• Daily fuel consumption: 25 tons (at 13 knots), 21 tons (at 11 knots)
• Range/voyage duration without bunkering: 80 days (at 13 knots), 98 days (at 11 knots)

The ship's powerplant consists of 4x Wartsila 16V32 dual-fuel engines (5,46 MW each, combined power output 21,84 MW), 1x Wartsila generator (model VASA 4R22/26, output 560 kW) 1x Marelli Motori generator (model M7BM400/MC8, output 640 kVA). The ship has one emergency diesel generator (MAN model D2542-MLE) with power output 330 kW.

All the four main diesel engines and the alternators/electric generators are on Upper Deck (beneath the Helideck). The location of the Engine Room is uncommon but greatly improves the vessel's seakeeping/seaworthiness (as the center of gravity is higher) and also benefits the powerplant's maintenance (as the heavy components are easily handled by the forward Main Crane). The Engine Room's positioning above the waterline also allows the fuel tanks to be placed midship, which, in case of grounding, reduces the probability of oil spillage.

The propulsion system is diesel-electric and consists of 2x ABB (Stromberg-built fixed rear thrusters, each 7,5 MW/combined power output 15 MW) plus 1x ABB bow thruster (Jastram-built fixed variable speed electric drive with power output 1,72 MW). Each thruster is fitted with a four-bladed stainless steel propeller.

The icebreaker Otso is also fitted with switchboards (Stromberg model Mete-Marine, power 6,3 kV Ith 31,5 kA), two AC/DC transformers (each 1500 kVA), a multi-sensor radar, AIS positioning system, DF ECDIS (Dual-Fuel Electronic Chart Display and Information System), satellite communications, TV cable network, radio station (GMDSS A4), two VOIP phones, 5x searchlights (2x bow/3 kW, 2x bow/1 KW, 1x aft/3 KW), Fire Alarm System (Consilium, 2017-installed).

The vessel's life-saving equipment includes 2x lifeboats (portside and starboard, model Hatecke GSL-5,5C, capacity 35 seats each, weight 2,46 tons each/including equipment) and 4x liferafts (model Viking Life, capacity 25 seats each).

Drydocks/refurbishments

During the drydock in 2015, the icebreaker received the following modifications:

• flume tank (reducing the rolling effect in open sea)
• hull steelworks (ice-class was upgraded to A1-Super/PC4)
• new lifeboats, helicopter deck, infirmary
• A new Mezzanine Deck was installed (above the flume tank) fitted with a recycling station.

Decks and Cabins

The aft-located Helideck is a helicopter landing platform with max-load 2,9 tons.

The aft Cargo Deck is served by 1x Main Crane (forward, Bronto-built, max lifting capacity 5 tons), a pilot crane (aft, max lifting capacity 2 tons), an aft-mounted towing winch (Rauma-Repola model TW 600 H).

The Otso ship provides accommodation to maximum 35 persons (including 23x crew and 12x passengers/clients). Onboard facilities also include 2x Day Rooms/Messhalls/Cafeterias (1x crew, 1x for clients/both on Upper Deck), Laundry Room (on Deck 2), Gym (Bridge Deck 2), Sauna Room (Deck 2), Saloon/Lounge Room (Bridge Deck 4), Infirmary/Hospital (Bridge Deck 2), Kiosk (Upper Deck).

The crew includes 1x Master/Captain, 1x Chief Officer, 1x First Officer, 2x Second Officers, 1x Chief Engineer, 1x First Engineer, 1x Second Engineer, 1x Electrical Engineer, 1x Electrician, 1x Boatswain, 3x ABs (able seamen), 1x Engine Repairman, 2x Motormen, 1x Chief Steward, 1x First Cook, 1x Catering Assistant.

Note: In the case of poor AIS coverage, tracking the vessel's current location will be impossible. You can see CruiseMapper's list of all icebreakers and ice-breaking research ships in the "itinerary" section of our Icebreakers hub. All states and their fleets are listed there.