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.
Not all ships are built to an ice class. Building a ship to an ice class means that the hull must be thicker, and more scantlings must be in place. Sea chests may need to be arranged differently depending on the class. Sea bays may also be required to ensure that the sea chest does not become blocked with ice. Most of the stronger classes require several forms of rudder and propeller protection. Two rudder pintles are usually required, and strengthened propeller tips are often required in the stronger ice classes. More watertight bulkheads, in addition to those required by a ship's normal class, are usually required. In addition, heating arrangements for fuel tanks, ballast tanks, and other tanks vital to the ship's operation may also be required depending on the class.
Ships can be assigned one of seven Polar Classes (PC) 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 based on the Unified Requirements for Polar Class Ships developed by the International Association of Classification Societies (IACS). [1] The IACS Polar Class rules were developed to harmonize the ice class rules between different classification societies and complement the IMO Guidelines for Ships Operating in Arctic Ice Covered Waters.
Traffic restrictions in the Baltic Sea during winter months are based on the Finnish-Swedish ice classes. These restrictions, imposed by the local maritime administrations, declare the minimum requirements for ships that are given icebreaker assistance, for example "ice class 1A, 2000 DWT". [2]
In the Finnish-Swedish ice class rules, merchant ships operating in first-year ice in the Baltic Sea 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 Swedish Maritime Administration and the Finnish Transport and Communications Agency (Traficom). [3] International classification societies have incorporated the Finnish-Swedish ice class rules to their own rulebooks and offer equivalent ice class notations that are recognized by the Finnish and Swedish authorities. [4]
Ships of the highest ice class, 1A Super, are designed to operate in difficult ice conditions mainly without icebreaker assistance while ships of lower ice classes 1A, 1B and 1C are assumed to rely on icebreaker assistance. In addition there are ice class 2 for steel-hulled ships with no ice strengthening that are capable of operating independently in very light ice conditions and class 3 for vessels that do not belong to any other class such as barges. [5] In official context and legislation, the ice classes are usually spelled with Roman numerals, e.g. IA. [3] Classification societies may sometimes use somewhat different distinguishing marks for Finnish-Swedish ice classes; for example, 1A Super is defined as Ice Class I AA by the American Bureau of Shipping (ABS) and ICE(1A*) by DNV GL. [4]
The American Bureau of Shipping has a system of ice classes which includes classes A5 through A0; B0, C0, and D0. A5 class is the strongest built of the classes, with D0 being the weakest. All other major classification societies have a similar system of ice classes, and converting between ice classes is relatively easy. In most cases only the names of the classes are changed and the specifics of the Arctic class are identical. ABS Class A5 is the only Arctic Class that may act independently in extreme Arctic waters with no limitations. Other classes are subject to limitations on time of year, required escort (always with a vessel of higher ice class) and ice conditions.
Prior to the adoption of Unified Requirements for Polar Class Ships, DNV (Det Norske Veritas until 2013; DNV GL in 2013–2021) maintained its own set of requirements for ships operating independently in freezing sub-Arctic, Arctic and Antarctic waters. Ships operating in first-year winter ice with pressure ridges could be assigned class notation ICE-05, -10, or -15 where the number indicated nominal ice thickness used for structural design; for example, 0.5 metres (20 in) for ICE-05. Vessels expected to encounter multi-year sea ice and glacial ice inclusions could be assigned more stringent requirements class notation with POLAR-10, -20, or -30. Finally, vessels intended for icebreaking as their main purpose could be assigned an additional class notation "Icebreaker" after the ice class, e.g. POLAR-10 Icebreaker. [6]
Following the merger of Det Norske Veritas and Germanischer Lloyd in 2013, the old Det Norske Veritas ice class rules were superseded by new DNV GL ice classes. [7]
DNV GL rules include requirements and additional class notations Ice(C) and Ice(E) for ships intended for service in waters with light ice conditions and localized drift ice, Ice(1C) through Ice(1A*) for vessels operating in northern Baltic Sea (corresponding to Finnish-Swedish ice classes 1C through 1A Super), an additional notation Ice(1A*F) for high-powered ships in regular traffic in heavy Baltic ice, and PC(1) through PC(7) for ships meeting the IACS Polar Class requirements. Ships engaged in icebreaking operations may be assigned an additional notation "Icebreaker" and ships designed to operate stern-first in ice an additional notation DAV. [7]
The Russian Maritime Register of Shipping (RS), established in 1913, has a long history of classing icebreakers and ice-strengthened vessels, and today maintains its own set of ice class rules for vessels navigating in freezing non-Arctic and Arctic seas. Out of about 5,000 vessels classified by the RS, over 3,200 are strengthened for navigation in ice and 300 of these have an ice class intended for operations in Arctic waters. [8]
The RS ice class rules have been revised and the class notations changed several times over the years. As of 2017 [update] , the ice classes are divided to non-Arctic, Arctic and icebreaker classes. The ice class notation is followed by a number which denotes the level of ice strengthening: Ice1 to Ice3 for non-Arctic ships, Arc4 to Arc9 for Arctic ships, and Icebreaker6 to Icebreaker9 for icebreakers. These ice classes can be assigned in parallel with the Finnish-Swedish ice class and/or the IACS Polar Class, provided the vessel complies with all applicable rules. The selection of ice class is based on the operating area in the Russian Arctic, time of year, ice conditions, operating tactics, and whether the vessel operates under icebreaker escort or independently. In addition, icebreaker classes have additional requirements for minimum shaft power and icebreaking capability. [9]
Ice classification by Lloyd's Register based on Baltic Sea and Arctic Ocean conditions. [10]
| Class Range | Ice Class | First year ice thickness (Baltic) | First year ice thickness (Polar) |
|---|---|---|---|
| Lowest | 1C | 0.4 m | |
| 1B | 0.6 m | ||
| 1A | 0.8 m | 0.3–0.7 m | |
| Highest | 1AS | 1.0 m | 0.7–1.2 m |
A class attributed to a vessel under the Canadian Arctic Shipping Pollution Prevention Regulations regime, which indicates that the vessel met the requirements of those regulations. Up to December 2017, Canadian Arctic Shipping Pollution Prevention Regulations [11] establish 9 Arctic classes for ship (Arctic Class 1, 1A, 2, 3, 4, 6, 7, 8 or 10) based on requirements for hull structural design, engine power, engine cooling water arrangement, propeller, rudder and steering gear and performance in ice.
| Ice Class index | Arctic Class | Description |
|---|---|---|
| Higher | 10 | |
| 8 | ||
| 7 | Can maintain a speed of 3 knots through ice 7 feet thick | |
| 6 | ||
| 4 | Can maintain a speed of 3 knots through ice 4 feet thick | |
| 3 | Can maintain a speed of 3 knots through ice 3 feet thick | |
| 2 | ||
| 1A | ||
| Lower | 1 |
Source: [12]
A class attributed to a vessel under the Canada Shipping Act regime, which indicates that the vessel met the requirements of the applicable standards of TP 12260 Equivalent Standards for the Construction of Arctic Class Ships, published by the Department of Transport, on December 1, 1995. [13] This new system exists for determining how the most highly ice-strengthened vessels are classed by Transport Canada, Marine Safety. Four Canadian Arctic Classes (CAC) have now replaced the previous Arctic 1 - Arctic 10 Classes. Details of the new structural classifications are provided in the Transport Canada publication Equivalent Standards For The Construction Of Arctic Class Ships - TP 12260E; to summarize:
Vessels CAC 1, 2, 3, and 4 may also be considered suitable escorts, capable of escorting ships of lower classes. Canada has developed structural standards for each of these classes. Ships built to polar standards of other Classification Societies and national authorities can apply for CAC equivalency on a case-by-case basis, as can owners of vessels previously classified under the existing Canadian system for Arctic Class vessels.
| Category | Equivalent Arctic Class | |
|---|---|---|
| CAC 1 | → | Arctic Class 10 |
| CAC 2 | → | Arctic Class 8 |
| CAC 3 | → | Arctic Class 6 |
| CAC 4 | → | Arctic Class 3 |
Note: The CAC categories are equivalent to the Arctic Classes as shown in table. These nominal equivalencies are not reciprocal.
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.
MV Arctic was an icebreaking cargo ship built in 1978 at the Port Weller Dry Docks in St. Catharines, Ontario, Canada. The ship was owned and operated by the Fednav Group. Arctic was sold for recycling in Aliağa, Turkey in April 2021.
MSV Fennica is a Finnish multipurpose icebreaker and offshore support vessel. Built in 1993 by Finnyards in Rauma, Finland and operated by Arctia Offshore, she was the first Finnish icebreaker designed to be used as an escort icebreaker in the Baltic Sea during the winter months and in offshore construction projects during the open water season. Fennica has an identical sister ship, Nordica, built in 1994.
Taymyr is a shallow-draft nuclear-powered icebreaker, and the first of two similar vessels. She was built in 1989 for the Soviet Union in Finland, at the Helsinki Shipyard by Wärtsilä Marine, by order of the Murmansk Shipping Company. Her sister ship is Vaygach.
Vaygach is a shallow-draught nuclear-powered icebreaker. She was built in 1989 for the Soviet Union by Wärtsilä Marine Helsinki Shipyard in Finland by order of the Murmansk Shipping Company and its KL-40 reactor was installed at the Baltic Shipyard in St. Petersburg. Her sister ship is Taymyr.
SCF Sakhalin is a Russian icebreaking platform supply and standby vessel owned by SCF Sakhalin Vessels Limited, a subsidiary of Sovcomflot. The ship was built by Aker Finnyards Helsinki shipyard in Finland in 2005 as FESCO Sakhalin for Far East Shipping Company (FESCO), but was purchased by Sovcomflot and renamed in 2010. Since the beginning it has been in long-term charter for Exxon Neftegas Ltd. and used to supply oil platforms in the Sakhalin-I project.
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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.
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.
MSV Botnica is a multipurpose offshore support vessel and icebreaker built by Finnyards in Rauma, Finland in 1998. She was the newest and technically most advanced state-owned icebreaker of Finland until 2012, when she was sold to the Port of Tallinn, Estonia for 50 million euro. Botnica is used as an escort icebreaker in the Baltic Sea during the winter months and it carries out subsea and offshore construction works worldwide during the open water season.
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.
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