Ice navigation vessel or Ice-strengthened vessel is a class of ships specially prepared for independent ice navigation in the waters of the polar seas and for following icebreakers in especially difficult ice conditions. [1] [2] Various registration authorities assign ice classes to vessels based on their technical characteristics. [3] [4] Due to this, ice navigation vessels are usually referred to as ice-class vessels without indicating which class they belong to, but indicating the type of vessel (e.g. ice-class tanker, ice-class cargo ship etc). [5]
The geometry of the hull contours of ice navigation ships is intermediate between the contours of an icebreaker and the shape of a conventional transport vessel. The reliability of any vessel of this type is determined by their ability to withstand the loads acting on them while sailing in ice at a given speed, as well as the loads from compression by ice masses. [6] The target capabilities determine the requirements for enhanced capacity of its engine, the strength of the hull, propellers, propeller shaft and steering gear. It may also include adaptations for functioning in freezing conditions, equipment necessary for navigation in ice and anti-icing system for the hull.
The ice navigation ships are also often referred as ice-strengthened vessels. This term has no international standard and its definition may vary in different countries. [2] [7] In general, it is more commonly used for various research and expedition ships and less commonly for merchant cargo ships. The common characteristics of these vessels are the presence of an ice belt or a double hull with its geometry similar to that of icebreakers. Also, the hull is made of durable materials and is smooth and free of protruding fasteners to reduce friction. The water intake is designed so that the engine is not clogged with ice, the ship's rudder and propeller are protected from external damage. [2]
The term icebreaker-transport vessels is applied to a part of ice navigation vessels, namely, to such cargo and research vessels that are capable of systematic navigation through the ice of freezing non-polar and polar seas during the entire navigation season, both independently and in cooperation with an icebreaker. [8] Following the example of the Sevmorput ship, which is referred to as them, ice navigation ships are called icebreaker-transport ships if the capacity of their ship engines allows free navigation in ice and they most likely do not need to be accompanied by an icebreaker. [9] The shaft power of some vessels of this class can be comparable to the most powerful icebreakers currently in existence. For example, the shaft power of Yamalmax-type ships is 45 MW, [10] and the same figure for nuclear-powered icebreakers of Arktika-class is 49.5 MW. [11] And since specialized icebreakers are also actively used for transport purposes within their capabilities, the term “icebreaker-transport vessel” is often applied to them too. Thus, in general, the assignment of transport ships to this class means that they can be classified as icebreakers according to their technical characteristics and means that, despite their main transport purpose, they can be used as icebreakers for other ships if they have similar routes. [10]
Compared to conventional icebreakers, vessels of this class can overcome ice hummocks more efficiently due to their greater mass. But since all merchant vessels as a whole have long sides, which, in the case of movement in ice, create significant friction and resistance to the movement of the vessel, in a number of cases they need the assistance of icebreakers, despite the high capacity of their ship engines. [12] The elongated shape of these vessels also increases their susceptibility to sea ice compression.
And by analogy with the informal term "ice-class ship", clarifications by the type of ship are used for this class of vessels too. For example, an icebreaker-transport container ship or, for short, an icebreaker-container ship in the case of Sevmorput, an icebreaker-tanker in the case of Timofey Guzhenko, etc. [13] Since the characteristics of ships of this class and their icebreaking ability are close to conventional icebreakers, the names "the biggest icebreaker in history" or "the biggest icebreaker in the world" are sometimes used for large vessels.
One of the varieties of ice navigation vessels are double-acting ships. To move through the ice, they use the combined effect of the ice-breaking shape of the ship's stern and the effect of the propellers on the ice. [14] These vessels may have the usual bulbous bow and may be capable of moving in ice only astern. Since ice sailing astern also eliminates the stress on the hull that occurs when breaking ice in the classical way, this type of vessel has advantages. Due to the icebreaking use of their stern, it is impossible to equip these ships with a conventional rudder and they can only be driven by rudder propellers. It should also be noted that ships with an icebreaking shape of the bow and stern, as a rule, move through the ice in the classical way to reduce propeller wear and use stern forward movement only in severe ice conditions.
An icebreaker is a special-purpose ship or boat designed to move and navigate through ice-covered waters, and provide safe waterways for other boats and ships. Although the term usually refers to ice-breaking ships, it may also refer to smaller vessels, such as the icebreaking boats that were once used on the canals of the United Kingdom.
MV Captain Kurbatskiy was a Russian SA-15 type cargo ship originally known as Nizhneyansk (Нижнеянск) after a port of the same name. The ship was delivered from Valmet Vuosaari shipyard in 1983 as the second ship of a series of 19 icebreaking multipurpose arctic freighters built by Valmet and Wärtsilä, another Finnish shipbuilder, for the Soviet Union for year-round service in the Northern Sea Route. These ships, designed to be capable of independent operation in arctic ice conditions, were of extremely robust design and had strengthened hulls resembling those of polar icebreakers.
MT Petali is an Aframax crude oil tanker. Formerly known as Mastera for almost two decades and briefly as Mikines in early 2022 and Alma until September 2023, she and her sister ship Tempera were the first ships to utilize the double acting tanker (DAT) concept in which the vessel is designed to travel ahead in open water and astern in severe ice conditions. The icebreaking tanker was built to transport crude oil year-round from the Russian oil terminal in Primorsk to Neste Oil refineries in Porvoo and Naantali.
La Noumbi is a floating production storage and offloading (FPSO) unit operated by Perenco. The vessel, converted from the former Finnish Aframax crude oil tanker Tempera by Keppel Corporation, will replace an older FPSO unit in the Yombo field off the Republic of Congo in 2018.
Ice class refers to a notation assigned by a classification society or a national authority to denote the additional level of strengthening as well as other arrangements that enable a ship to navigate through sea ice. Some ice classes also have requirements for the ice-going performance of the vessel.
Magadan is a Russian icebreaker and the second vessel in a series of three subarctic icebreakers built at Wärtsilä Helsinki shipyard in Finland in 1982–1983. The vessel's sister ships are Mudyug and Dikson.
Polar Class (PC) refers to the ice class assigned to a ship by a classification society based on the Unified Requirements for Polar Class Ships developed by the International Association of Classification Societies (IACS). Seven Polar Classes are defined in the rules, ranging from PC 1 for year-round operation in all polar waters to PC 7 for summer and autumn operation in thin first-year ice.
MT Indiga was an ice-strengthened product tanker that sailed under the Finnish flag in 1976–2003 and under the Russian flag in 2003–2021. After her modernization in 1994 she became the second merchant ship, after her sister ship Varzuga, to be equipped with an electric azimuth thruster called Azipod.
MT Varzuga was an ice-strengthened product tanker that sailed under the Finnish flag in 1977–2003 and under the Russian flag in 2003–2021. After her modernization in 1993, she became the first merchant ship to be equipped with Azipod, an electric azimuthing propulsion unit developed in Finland in the late 1980s. She was also the first non-Soviet ship to transit the Northern Sea Route.
A double acting ship is a type of icebreaking ship designed to travel forwards in open water and thin ice, but turn around and proceed astern (backwards) in heavy ice conditions. In this way, the ship can operate independently in severe ice conditions without icebreaker assistance but retain better open water performance than traditional icebreaking vessels.
SA-15 is the project name for a series of icebreaking multipurpose cargo ships built in Finland for the Soviet Union in the 1980s. The ships, capable of independent operation in all prevailing arctic ice conditions, were the first merchant vessels designed for year-round operations in the Northern Sea Route. For this purpose they have hulls that resemble those of polar icebreakers and propulsion systems capable of withstanding ice loads.
Vladimir Ignatyuk is a Russian icebreaking anchor handling tug supply vessel. She was built by Burrard-Yarrows Corporation in Canada in 1983 as Kalvik as part of an Arctic drilling system developed by BeauDril, the drilling subsidiary of Gulf Canada Resources. After the offshore oil exploration in the Beaufort Sea ended in the early 1990s, she was sold to the Canadian shipping company Fednav in 1997 and renamed Arctic Kalvik. In 2003, she was purchased by Murmansk Shipping Company and transferred to Russia.
Finnish-Swedish ice class is an ice class assigned to a vessel operating in first-year ice in the Baltic Sea and calling at Finnish or Swedish ports. Ships are divided into six ice classes based on requirements for hull structural design, engine output and performance in ice according to the regulations issued by the Finnish Transport and Communications Agency (Traficom) and the Swedish Maritime Administration.
Voima is a Finnish state-owned icebreaker. Built by Wärtsilä Hietalahti shipyard in Helsinki in 1954, she was the first icebreaker in the world to be equipped with two bow propellers and generated widespread publicity that helped the Finnish shipbuilding industry to become the world leader in icebreaker design.
An oblique icebreaker is a special type of icebreaker designed to operate not only ahead and astern, but also obliquely (sideways) with a large angle of attack. In this way, a relatively small icebreaker is capable of opening a wide channel in ice for large merchant ships.
Moskva was a Soviet polar icebreaker and the lead ship of a series of five diesel-electric icebreakers named after major Soviet cities. She was built at Wärtsilä Hietalahti shipyard in Helsinki, Finland, in 1959 and when delivered was the largest and most powerful non-nuclear icebreaker ever built. Shortly after the dissolution of the Soviet Union, Moskva was decommissioned after a long and successful career along the Northern Sea Route and sold for scrap in 1992.
Robert LeMeur was an icebreaking platform supply vessel used to support oil exploration in the Beaufort Sea. Built in 1982 by Burrard Yarrows Corporation in Vancouver, British Columbia, she was part of the fleet of Canadian icebreakers, drillships and support vessels operated by Canadian Marine Drilling (Canmar), the drilling subsidiary of Dome Petroleum and later Amoco Canada Petroleum Company.
Yuriy Kuchiev is an icebreaking gas condensate tanker operated by the Greek shipowner Dynacom. The vessel, built at Arctech Helsinki Shipyard in Finland, utilizes the double acting ship principle to allow independent operation without icebreaker escort in ice-covered seas. The vessel was delivered to the owner in August 2019.
Kigoriak is a Russian icebreaking anchor handling tug supply vessel. Built by Saint John Shipbuilding & Dry Dock Company for Canadian Marine Drilling (Canmar) in 1979 as Canmar Kigoriak, she was the first commercial icebreaking vessel developed to support offshore oil exploration in the Beaufort Sea.
Dikson is a Russian icebreaker and the final vessel in a series of three subarctic icebreakers built at Wärtsilä Helsinki shipyard in Finland in 1982–1983. The vessel's sister ships are Mudyug and Magadan.
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