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Polar Class (PC) refers to the
ice class 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 ...
assigned to a
ship A ship is a large watercraft, vessel that travels the world's oceans and other Waterway, navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally disti ...
by a
classification society A ship classification society or ship classification organisation is a non-governmental organization that establishes and maintains technical standards for the construction and operation of Shipping, ships and Offshore platform, offshore structure ...
based on the ''Unified Requirements for Polar Class Ships'' developed by the
International Association of Classification Societies The International Association of Classification Societies (IACS) is a technically based non-governmental organization that currently consists of twelve member marine classification societies. More than 90% of the world's cargo-carrying ships’ ...
(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.Unified Requirements for Polar Class ships
. International Association of Classification Societies (IACS), April 2016.
The IACS Polar Class rules should not be confused with International Code for Ships Operating in Polar Waters (Polar Code) by the
International Maritime Organization The International Maritime Organization (IMO; ; ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations responsible for regulating maritime transport. The IMO was established following agreement at a ...
(IMO).


Background

The development of the Polar Class rules began in the 1990s with an international effort to harmonize the requirements for marine operations in the polar waters in order to protect life, property and the environment. The guidelines developed by the International Maritime Organization (IMO), which were later incorporated in the Polar Code,Kendrick, A
''Polar Ship Design Standards – State of the Art, and Way Forward''
.
made reference to the compliance with ''Unified Requirements for Polar Ships'' developed by the International Association of Classification Societies (IACS). In May 1996, an "Ad-Hoc Group to establish Unified Requirements for Polar Ships (AHG/PSR)" was established with one working group concentrating on the structural requirements and another working on machinery-related issues. The first IACS Polar Class rules were published in 2007.History Files (HF) and Technical Background (TB) documents for Unified Requirements (URs)
. International Association of Classification Societies (IACS), December 2016.
Prior to the development of the unified requirements, each classification society had their own set of ice class rules ranging from Baltic ice classes intended for operation in first-year ice to higher vessel categories, including icebreakers, intended for operations in polar waters. When developing the upper and lower boundaries for the Polar Classes, it was agreed that the highest Polar Class vessels (PC 1) should be capable of operating safely anywhere in the Arctic or the Antarctic waters at any time of the year while the lower boundary was set to existing tonnage operating during the summer season, most of which followed the Baltic ice classes with some upgrades and additions. The lowest Polar Class (PC 7) was thus set to the similar level with the Finnish-Swedish ice class 1A. The definition of operational conditions for each Polar Class was intentionally left vague due to the wide variety of ship operations carried out in polar waters.


Definition


Polar Class notations

The IACS has established seven different Polar Class notations, ranging from PC 1 (highest) to PC 7 (lowest), with each level corresponding to operational capability and strength of the vessel. The description of ice conditions where ships of each Polar Class are intended to operate are based on
World Meteorological Organization The World Meteorological Organization (WMO) is a List of specialized agencies of the United Nations, specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology an ...
(WMO) ''Sea Ice Nomenclature''. These definitions are intended to guide owners, designers and administrations in selecting the appropriate Polar Class to match the intended voyage or service of the vessel. Ships with sufficient power and strength to undertake "aggressive operations in ice-covered waters", such as escort and ice management operations, can be assigned an additional notation "
Icebreaker 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 ...
". The two lowest Polar Classes (PC 6 and PC 7) are roughly equivalent to the two highest
Finnish-Swedish ice class Finnish-Swedish ice class is an ice class assigned to a vessel operating in first-year ice in the Baltic Sea and calling at Finland, Finnish or Sweden, Swedish ports. Ships are divided into six ice classes based on requirements for hull structura ...
es (1A Super and 1A, respectively).Finnish ice classes equivalent to class notations of recognized classification societies and documentation required for the determination of the ice classes of ships
Maritime Safety Regulation TRAFI/31299/03.04.01.00/2010, Finnish Transport Safety Agency, 23 November 2010.
However, unlike the Baltic ice classes intended for operation only in first-year sea ice, even the lowest Polar Classes consider the possibility of encountering multi-year ice ("old ice inclusions").


Requirements

In the Polar Class rules, the hull of the vessel is divided longitudinally into four regions: "bow", "bow intermediate", "midbody" and "stern". All longitudinal regions except the bow are further divided vertically into "bottom", "lower" and "icebelt" regions. For each region, a design ice load is calculated based on the dimensions, hull geometry, and ice class of the vessel. This ice load is then used to determine the
scantlings Scantling is a measurement of prescribed size, dimensions, or cross sectional areas. When used in regard to timber, the scantling is (also "the scantlings are") the thickness and breadth, the sectional dimensions; in the case of stone it refers t ...
and steel grades of structural elements such as shell plating and frames in each location. The design scenario used to determine the ice loads is a glancing collision with a floating ice floe. In addition to structural details, the Polar Class rules have requirements for machinery systems such as the main propulsion, steering gear, and systems essential for the safety of the crew and survivability of the vessel. For example, propeller-ice interaction should be taken into account in the propeller design, cooling systems and sea water inlets should be designed to work also in ice-covered waters, and the ballast tanks should be provided with effective means of preventing freezing. Although the rules generally require the ships to have suitable hull form and sufficient propulsion power to operate independently and at continuous speed in ice conditions corresponding to their Polar Class, the ice-going capability requirements of the vessel are not clearly defined in terms of speed or ice thickness. In practice, this means that the Polar Class of the vessel may not reflect the actual icebreaking capability of the vessel.


Polar Class ships

The IACS Polar Class rules apply for ships contracted for construction on or after 1 July 2007. This means that while vessels built prior to this date may have an equivalent or even higher level of ice strengthening, they are not officially assigned a Polar Class and may not in fact fulfill all the requirements in the unified requirements. In addition, particularly Russian ships and icebreakers are assigned ice classes only according to the requirements of the
Russian Maritime Register of Shipping The Russian Maritime Register of Shipping (RMRS) () maintains a ship registration, ship register of the Russia, Russian Federation, based in Saint Petersburg, and is a marine classification society. Its activities aim to enhance safety of naviga ...
, which maintains its own ice class rules parallel to the IACS Polar Class rules. Although numerous ships have been built to the two least hardened Polar Classes, PC6 and PC7, only a small number of ships have been assigned ice class PC5 or higher.


Polar Class 5

A number of
research vessel A research vessel (RV or R/V) is a ship or boat designed, modified, or equipped to carry out research at sea. Research vessels carry out a number of roles. Some of these roles can be combined into a single vessel but others require a dedicated ...
s intended for scientific missions in the polar regions are built to PC5 rating: the South African ''
S. A. Agulhas II ''S. A. Agulhas II'' is a South African icebreaking polar supply and research vessel owned by the Department of Forestry, Fisheries and the Environment. She was built in 2012 by STX Finland Rauma shipyard in Rauma, Finland, to replace the ...
'' in 2012, the American ''Sikuliaq'' in 2014, and the British RRS ''Sir David Attenborough'' in 2020.Hull strengthened to PC4. In addition, a PC5 Antarctic vessel ''Almirante Viel'' was commissioned for the
Chilean Navy The Chilean Navy () is the naval warfare service branch of the Chilean Armed Forces. It is under the Ministry of National Defense (Chile), Ministry of National Defense. Its headquarters are at Edificio Armada de Chile, Valparaiso. History Ori ...
in July 2024. In 2012, the
Royal Canadian Navy The Royal Canadian Navy (RCN; , ''MRC'') is the Navy, naval force of Canada. The navy is one of three environmental commands within the Canadian Armed Forces. As of February 2024, the RCN operates 12 s, 12 s, 4 s, 4 s, 8 s, and several auxiliary ...
awarded a shipbuilding contract for the construction of six Arctic Offshore Patrol Ships (AOPS) rated at PC5.Bow strengthened to PC4. , the first four vessels (, , and ) have entered service, the fifth () has been delivered, and the sixth () is being fitted out. Two additional ships, and , are under construction for the
Canadian Coast Guard The Canadian Coast Guard (CCG; ) is the coast guard of Canada. Formed in 1962, the coast guard is tasked with marine search and rescue (SAR), communication, navigation, and transportation issues in Canadian waters, such as navigation aids and i ...
. , four cruise ships have been built with PC5 rating: ''
National Geographic Endurance National may refer to: Common uses * Nation or country ** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen Places in the United States * National, Maryland, ce ...
'' (delivered in 2020) and ''
National Geographic Resolution National may refer to: Common uses * Nation or country ** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen Places in the United States * National, Maryland, ce ...
'' (2021) for
Lindblad Expeditions Lindblad Expeditions (Lindblad Expeditions-National Geographic, ) is an expedition travel company headquartered in New York, NY. The company currently offers expedition cruises to destinations on all seven continents aboard 15 ships with capacit ...
, and '' SH Minerva'' (2021) and '' SH Vega'' (2022) for
Swan Hellenic Swan Hellenic is a British cruise line specialising in expedition tours of historical or cultural interest aimed at the upper end of the cruise market. Swan Hellenic was first established as Swan's Tours in the 1950s as a tour operator carrying ...
.


Polar Class 4

The 2012-built
drillship A drillship is a merchant vessel designed for use in exploratory offshore drilling of new oil and gas wells or for scientific drilling purposes. In recent years the vessels have been used in deepwater and ultra-deepwater applications, equipped ...
'' Stena IceMAX'' has a hull strengthened according to PC4 requirements.Propulsion units strengthened to
Det Norske Veritas Det Norske Veritas (DNV), formerly DNV GL, is an international accredited registrar and classification society headquartered in Høvik, Norway. DNV provides services for several industries, including maritime, oil and gas, renewable energy, e ...
ICE-10 rating.
However, the long and wide vessel does not feature an icebreaking hull and is designed to operate primarily in pre-broken ("managed") ice. The Canadian shipping company
Fednav Fednav is a privately owned Canadian company in the maritime transport industry, involved in transporting over 30 million tonnes of bulk cargo and break bulk cargo worldwide. Its fleet comprises approximately 120 long-term and spot-chartered ves ...
operates two PC4 rated
bulk carriers A bulk carrier or bulker is a merchant ship specially designed to transport unpackaged bulk cargo—such as grain, coal, ore, steel coils, and cement—in its cargo holds. Since the first specialized bulk carrier was built in 1852, economic f ...
, 2014-built ''Nunavik'' and 2021-built ''
Arvik I Owrang (, also Romanized as Avarang and Avrang; also known as Arvik) is a village in Azghan Rural District, in the Central District (Ahar County), Central District of Ahar County, East Azerbaijan Province, Iran. At the 2006 census, its population w ...
''. The 28,000-tonne vessels are primarily used to transport nickel ore from
Raglan Mine Raglan Mine is a large nickel mining complex in the Nunavik region of northern Quebec, Canada. It is located approximately south of Deception Bay. Discovery of the deposits is credited to Murray Edmund Watts in 1931 or 1932. It is owned and ope ...
in the Canadian Arctic. In 2015, the hull of the Finnish 1986-built icebreaker ''Otso'' was reinforced with additional steel to PC4 level to allow the vessel to support seismic surveys in the Arctic during the summer months. The Finnish LNG-powered icebreaker ''Polaris'', built in 2016, is rated PC4 with an additional
Lloyd's Register Lloyd's Register Group Limited, trading as Lloyd's Register (LR), is a technical and professional services organisation and a maritime classification society, wholly owned by the Lloyd’s Register Foundation, a UK charity dedicated to research ...
class notation "Icebreaker(+)". The latter part of the notation refers to additional structural strengthening based on analysis of the vessel's operational profile and potential ice loading scenarios. The interim icebreakers CCGS ''Captain Molly Kool'', CCGS ''Jean Goodwill'', and CCGS ''Vincent Massey'', built in 2000–01 and acquired by the
Canadian Coast Guard The Canadian Coast Guard (CCG; ) is the coast guard of Canada. Formed in 1962, the coast guard is tasked with marine search and rescue (SAR), communication, navigation, and transportation issues in Canadian waters, such as navigation aids and i ...
2018, were upgraded to PC4 rating as part of the vessels' conversion to Canadian service. In December 2024, the
Institute of Deep-sea Science and Engineering An institute is an organizational body created for a certain purpose. They are often research organisations (research institutes) created to do research on specific topics, or can also be a professional body. In some countries, institutes ca ...
of the
Chinese Academy of Sciences The Chinese Academy of Sciences (CAS; ) is the national academy for natural sciences and the highest consultancy for science and technology of the People's Republic of China. It is the world's largest research organization, with 106 research i ...
took delivery of the PC4 rated icebreaking research vessel '' Tan Suo San Hao''. The new PC4 polar logistics vessel of the
Argentine Navy The Argentine Navy (ARA; ). This forms the basis for the navy's ship prefix "ARA". is the navy of Argentina. It is one of the three branches of the Armed Forces of the Argentine Republic, together with the Argentine Army, Army and the Argentine ...
intended to complement the country's existing icebreaker ARA ''Almirante Irízar'' in Antarctica is currently in design stage. The
Japan Agency for Marine-Earth Science and Technology The , or JAMSTEC (海洋機構), is a Japanese national research institute for marine-earth science and technology. It was founded as Japan Marine Science and Technology Center (海洋科学技術センター) in October 1971, and became an Inde ...
(JAMSTEC) is in the process of acquiring a new PC4 rated icebreaker for researching the Arctic region. The
Swedish Maritime Administration The Swedish Maritime Administration () is the government agency in Sweden which provides services to the transport sector by keeping the sea lanes open and safe. The agency is to a certain degree financed through fees levied on commercial shippin ...
is in the process of acquiring a new icebreaker rated PC4 Icebreaker(+). The vessel is expected to enter service in 2028. The new Canadian Coast Guard Multi-Purpose Vessels (MPV) will be rated PC4 Icebreaker(+). Sixteen vessels will be built by
Seaspan Seaspan ULC (formerly Seaspan Marine Corporation) provides marine-related services to the Pacific Northwest. Within the Group are three (3) shipyards, an intermodal ferry and car float business, along with a tug and barge transportation compan ...
in the 2020s and 2030s, and the first vessel is expected to enter service in 2028.


Polar Class 3

The first PC3 vessels were two heavy load carriers, '' Audax'' and '' Pugnax'', built for the Netherlands-based ZPMC-Red Box Energy Services in 2016. The long and wide vessels, capable of breaking up to ice independently, were built for year-round transportation of
LNG Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume o ...
liquefaction In materials science, liquefaction is a process that generates a liquid from a solid or a gas or that generates a non-liquid phase which behaves in accordance with fluid dynamics. It occurs both naturally and artificially. As an example of t ...
plant modules to Sabetta. Although usually referred to by their
Russian Maritime Register of Shipping The Russian Maritime Register of Shipping (RMRS) () maintains a ship registration, ship register of the Russia, Russian Federation, based in Saint Petersburg, and is a marine classification society. Its activities aim to enhance safety of naviga ...
ice class Arc7, the fifteen first-generation
Yamalmax Yamalmax is a class of ice navigation tankers for the transportation of LNG with maximum dimensions that allow passing through the approach channel of the port of Sabetta located on the Yamal Peninsula (channel width , depth ). The project wa ...
LNG carrier An LNG carrier is a tank ship designed for transporting liquefied natural gas (LNG). Overview The first oceangoing liquified natural gas tanker in the world was '' Methane Pioneer'', which entered service in 1959 with a carrying capacity of ...
s built in 2016–2019 as well as the arctic condensate tankers ''Boris Sokolov'' (built in 2018) and ''Yuriy Kuchiev'' (2019) serving the
Yamal LNG Yamal LNG () is a joint venture led by Novatek based around a liquefied natural gas plant located in Sabetta at the north-east of the Yamal Peninsula, northwest Siberia, Russia. In addition to the LNG plant, the project includes production at the ...
project also have PC3 rating from
Bureau Veritas Bureau Veritas is a French company specialized in testing, inspection and certification founded in 1828. It operates in a variety of sectors, including building and infrastructure (27% of revenue), agri-food and commodities (23% of revenue), mar ...
. In April 2015, it was reported that Edison Chouest would build two PC3
anchor handling tug supply vessel Anchor Handling Tug Supply (AHTS) vessels are mainly built to handle anchors for oil rigs, tow them to location, and use them to secure the rigs in place. AHTS vessels sometimes also serve as Emergency Response and Rescue Vessels (ERRVs) and a ...
s (AHTS) for Alaskan operations. However, the construction of the vessels due for delivery by the end of 2016 was later cancelled following
Shell Oil Shell plc is a British multinational oil and gas company, headquartered in London, England. Shell is a public limited company with a primary listing on the London Stock Exchange (LSE) and secondary listings on Euronext Amsterdam and the New Y ...
's decision to halt Arctic oil exploration. , three polar research vessels have been built with PC3 rating: ''Kronprins Haakon'' for the
Norwegian Polar Institute The Norwegian Polar Institute (NPI; ) is Norway's central governmental institution for scientific research, mapping and environmental monitoring in the Arctic and the Antarctic. The NPI is a directorate under Norway's Ministry of Climate and Envir ...
in 2018, '' Xue Long 2'' for the
Polar Research Institute of China The Polar Research Institute of China () is the main research institute of the People's Republic of China for the study of Earth's polar regions. It is based in Shanghai, China. The Institute manages six polar research stations (five in Antarcti ...
in 2019, and ''Nuyina'' for the
Australian Antarctic Division The Australian Antarctic Division (AAD) is a division of the Department of Climate Change, Energy, the Environment & Water. The division undertakes science programs and research projects to contribute to an understanding of Antarctica and the S ...
in 2021. ''Kronprins Haakon'' also has the additional notation "Icebreaker" while ''Nuyina'' notation includes Lloyd's Register's "Icebreaker(+)" notation. The Finnish multipurpose icebreakers ''Fennica'' and ''Nordica'', built in the early 1990s, were assigned PC3 rating as part of the vessels' Polar Code certification in 2019. South Korea is in the process of acquiring a new Polar Class 3 research vessel for Arctic and Antarctic regions.


Polar Class 2

, the only PC2 rated vessel in service is the expedition cruise ship operated by the French company
Compagnie du Ponant Ponant (officially, ''Compagnie du Ponant'' ''(CDP)''; "Ponant Company") is a French cruise ship operator. It was founded in April 1988 by Philippe Videau, Jean-Emmanuel Sauvé, and other officers of the French Merchant Navy and launched the fi ...
. The 270-passenger vessel, capable of breaking up to thick multi-year ice and taking passengers to the
North Pole The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's rotation, Earth's axis of rotation meets its surface. It is called the True North Pole to distingu ...
, was delivered in 2021. The
United States Coast Guard The United States Coast Guard (USCG) is the maritime security, search and rescue, and Admiralty law, law enforcement military branch, service branch of the armed forces of the United States. It is one of the country's eight Uniformed services ...
has ordered two out of three planned PC2 rated heavy polar icebreakers referred to as Polar Security Cutters. The first contract was awarded in April 2019 and the second in December 2021. Construction of the first vessel, , has been delayed by several years and now is not expected to be delivered to the U.S. Coast Guard until at least 2030. While the vessels these Polar Security Cutters are intended to replace, and , are sometimes referred to as s, these mid-1970s icebreakers are not built in accordance with the IACS rules and do not carry a PC rating. In December 2024, the German research institute
Alfred Wegener Institute The Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (German: ''Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung'') is located in Bremerhaven, Germany, and a member of the Helmholtz Association ...
contracted
ThyssenKrupp Marine Systems TKMS –officially branded as ThyssenKrupp Marine Systems until June 2025– is a group and holding company of providers of naval vessels, surface ships and submarines. It was founded when large industrial conglomerate ThyssenKrupp acquired Howal ...
to build a replacement for the 1982-built research icebreaker ''Polarstern''. The new vessel, scheduled for delivery in 2030, will be rated PC2. In March 2025, the Government of Canada awarded construction contracts for two PC2 rated polar icebreakers for the Canadian Coast Guard under the National Shipbuilding Strategy
Polar Icebreaker Project The Polar Icebreaker Project (previously Polar Class Icebreaker Project) is an ongoing Canadian shipbuilding program under the National Shipbuilding Strategy. Announced in 2008 with an intention to replace the ageing with a new polar icebreak ...
. The first vessel will be built by Seaspan Vancouver Shipyards and the second, slightly smaller, by
Davie Shipbuilding Davie Shipbuilding is a shipbuilding company located in Lauzon, Quebec, Canada. The facility is now operating as Chantier Davie Canada Inc. and is the oldest continually operating shipbuilder in North America. History The Davie shipyard in Lauz ...
in co-operation with the Finnish Helsinki Shipyard. The vessels, named and , are expected to enter service in the early 2030s.


Polar Class 1

, no ships have been built, under construction, or planned to PC1, the highest ice class specified by the IACS.


Notes


References


External links


Unified Requirements for Polar Class ships
International Association of Classification Societies (IACS) * {{cite web , first = Claude , last = Daley , title = Ice Class Rules: Description and Comparison , date = April 2014 , url = http://www.engr.mun.ca/~cdaley/8074/Ice%20Class%20Rules_CD.pdf Shipbuilding Icebreakers Sea ice