Military


World Wide Icebreaker Classes

Ships operating in the Arctic environment are exposed to a number of unique risks. Poor weather conditions and the relative lack of good charts, communication systems and other navigational aids pose challenges for mariners. The remoteness of the areas makes rescue or clean-up operations difficult and costly. Cold temperatures may reduce the effectiveness of numerous components of the ship, ranging from deck machinery and emergency equipment to sea suctions. When ice is present, it can impose additional loads on the hull, propulsion system and appendages.

Guidelines for ships operating in Arctic ice-covered waters are intended to address those additional provisions deemed necessary for consideration beyond existing requirements of the SOLAS Convention, in order to take into account the climatic conditions of Arctic ice-covered waters and to meet appropriate standards of maritime safety and pollution prevention.

All the major classification societies have their own ice rules, with ice classes for various ice conditions. With a few exceptions, the classification societies are using the Finnish-Swedish Ice Class Rules (FSICR) for lighter ice classes in sub-arctic ice conditions. Generally, the FSICR notation differs between classification societies, even if the notation is actually referring to the same FSICR rule. For higher ice classes there are various ice rules and interpretations of the rules resulting in diverse ice notations and diverse designs for vessels intended for traffic even in the same sea areas. The comparison of different ice classes is difficult, as different rules emphasize different technical aspects. Several comparison tables have been created, but one has to remember that the comparison tables are always an approximation of the equivalence.

Each Classification Society has a set of rules for the strengthening for navigation in ice, and these are now in the process of harmonisation with the introduction of the International Association of Classification Societies (IACS) Polar Ship Rules. The IACS Polar Ship Rules are created in line with the IMO Guidelines for Ships Operating in Arctic Ice Covered Waters to provide comprehensive requirements for the safe navigation of ships in Arctic waters.

The Canadian Arctic Ice Regime Shipping System (AIRSS) uses ice conditions and vessel class to provide guidance on safe navigation in ice. Ships of Arctic Standard as prescribed by Canada's Arctic Shipping Pollution Prevention Regulations are divided into categories. The categories are based upon the purpose for which the vessel is designed. They are related to the manner in which a ship is designed to break ice, as well as the type or thickness of ice. The basic philosophy is that ships may be operated to their fullest capability within their structural capacity. For a Class 10 or Category 1 a ship which is designed and constructed for the purposes of unrestricted navigation in Canadian Arctic waters; and the management of large ice features. For Class 8 or Category 2 there is a requirement that the ship is fitted with a structural monitoring system that will enable the person in charge of navigation to determine the severity of ice loads during various operations, and if necessary, warn them to reduce the loads during ramming.

Not all ships which enter the Arctic environment will be able to navigate safely in all areas at all times of the year. A system of Polar Classes has therefore been developed to designate different levels of capability. In parallel to the development of other Guidelines, the International Association of Classification Societies (IACS) has developed a set of Unified Requirements which, in addition to general classification society rules, address all essential aspects of construction for ships of Polar Class.

Requirements of ice loads and scantlings vary among the currently available ice class rules. This reflects different design scenarios, concepts and ice mechanism assumptions embedded in the ice class rules of the different societies. Ice Class Rules establish design requirements for hull structures in an ice belt where the external hull surfaces will encounter ice. Strength requirements are specified for shell plating, frames (including local and main supporting members), and bulkheads. Some Ice Class Rules specify additional hull girder bending loads for vessels that may be raised by an ice pack. The strength requirements are accompanied with material requirements and abrasion/corrosion allowance. For machinery, quite varied engineering practices and design philosophies have been used in the development of the various ice class rules.

To establish greater consistency, IACS is working toward adopting a new set of Unified Requirements for Polar Class Ships (PCS). These will unify the ice class rules as well as respond to the need for a technical complement to the IMO Guidelines for Ships Operating in Arctic Ice-Covered Waters. A system of Polar Classes has been developed to designate different levels of capability for vessels navigating in certain areas at a certain time of the year in ice-covered water. Seven ice classes are proposed in the requirements, namely, PC1, PC2, PC3, PC4, PC5, PC6, and PC7.

Through cooperation with the Finnish Maritime Administration (FMA), the two lowest IACS polar classes (PC7/PC6) have been developed to align with the highest Baltic Ice Class (1A and 1A super). To maintain this alignment extensive calibration and validation for the ice load formulae were performed by the project team members from the five class societies (ABS, DNV, GL, LR, and RMRS), Canadian Transport and FMA.

POLAR CLASS GENERAL DESCRIPTION

  • PC 1 Year-round operation in all Arctic ice-covered waters
  • PC 2 Year-round operation in moderate multi-year ice conditions
  • PC 3 Year-round operation in second-year ice which may include multi-year ice inclusions
  • PC 4 Year-round operation in thick first-year ice which may include old ice inclusions
  • PC 5 Year-round operation in medium first-year ice which may include old ice inclusions
  • PC 6 Summer/autumn operation in medium first-year ice which may include old ice inclusions
  • PC 7 Summer/autumn operation in thin first-year ice with which may include old ice inclusions
In Canada the Arctic Ice Regime Shipping System (AIRSS) (Transport Canada, 1996) has been implemented as part of a revised Arctic Shipping Pollution Prevention Regulations (ASPPR, 1989). ASPPR is oriented to safety of shipping operations, setting requirements for hull strength, machinery strength and the limiting ice conditions in which various categories of vessels are permitted to operate. The AIRSS provides advice on whether a particular class of vessel can advance into an area having a specific set of ice conditions. In Russia, the Russian Registry maintains a classification of icebreakers and icebreaking vessels.

Nominal ship equivalencies
Finnish/Swedish (Baltic)Class*ASPPR Class Russian RegisterClass Polar Class
IA Super Type A UL PC6
IA Type B L1 PC7

The POLAR rules are intended for vessels operating unassisted in multi-year winter ice with floes and glacial inclusions as found in the Arctic, sub-Arctic and/or Antarctic regions. Occasional ramming is anticipated. The notation ensures that the vessel has sufficient strength and equipment to continuously operate in the specified ice conditions of the Arctic, sub-Arctic and/or Antarctic regions without icebreaker assistance. POLAR 10 definition are Vessels intended for ice breaking, built for another main purpose. Ice conditions: Winter ice with multi-year ice-floes and glacial ice inclusions. Accidental ramming. Figures indicate nominal ice thickness in dm. The use of the term "Polar Class" is somewhat confusing. Acording to the International Association of Classification Societies, all vessels operating in sea ice must be assigned a polar class, with PC 1 being capable of "Year-round operation in all Polar waters"

The stronger vessels to be assisted in all conditions are 1A super and 1A class ships. Weaker ice classes are 1B, 1C and 2 vessels, which are given assistance according to the ice conditions. A 1A super class vessel, for example, is required to have a strong hull and powerful engines. The more efficient 1A super and 1A class ships are able to sail unassisted in most ice conditions. Other vessels are usually assisted by icebreakers. In more severe ice conditions, they are towed.

UL

Ice strengthening notation of the ship (independent navigation in the Arctic in summer and autumn in light ice conditions and in the non-arctic freezing seas all the year round)

ULA

IIce strengthening notation of the ship (independent navigation in all areas of the World ocean in summer and autumn)

L1

Ice strengthening notation of the ship (independent navigation in the Arctic in summer in broken open ice and in the non-arctic freezing seas all the year round in light ice conditions

L2

Ice strengthening notation of the ship (independent navigation in the non-arctic seas in small open ice)

L3

Ice strengthening notation of the ship (independent navigation in the non-arctic seas in small open ice)

L4

Ice strengthening notation of the ship (independent navigation in the non-arctic seas in small open ice, short period)

LL1

Icebreaker category notation (intended for all kinds of icebreaking operations in the arctic seas on coastal routes and shore ice belt routes in high latitudes all the year round and capable of forcing the way in compact ice field over 2,0 m thick. The total shaft power is 47807 kW and over)

LL2

Icebreaker category notation (intended for all kinds of icebreaking operations in the arctic seas during the summer period and for operation on coastal routes during the winter period and capable of forcing the way in compact ice field less than 2,0 m thick. The total shaft power is 22065-47807 kW)

LL3

Icebreaker category notation (intended for all kinds of icebreaking operations in the non-arctic freezing seas, in shallow waters and mouths of rivers flowing into the arctic seas during the winter period without assistance as well as for operation on coastal routes in the arctic seas under convoy of icebreakers of higher category all the year round, and capable of forcing the way in compact ice field up to 1,5 m thick. The total shaft power is 11032-22065 kW)

LL4

Icebreaker category notation (intended for all kinds of icebreaking operations in harbour and roadstead water areas without assistance all the year round as well as for operations in the non-arctic freezing seas under convoy of icebreakers of higher category during the winter period, and capable of forcing the way in compact ice field up to 1,0 m thick. The total shaft power is under 11032 kW)

LL6

Icebreaker category notation (intended for icebreaking operations in harbour and roadstead water areas as well as in the non-arctic freezing seas with ice up to 1,5 m thick, and capable of forcing the way continuously running in compact ice field up to 1,0 m thick)

LL7

Icebreaker category notation (intended for icebreaking operations: on coastal routes of the arctic seas in winter and spring with ice up to 2,0 m thick and 2,5 m thick in summer and autumn; in the non-arctic freezing seas and mouths of rivers flowing into the arctic seas with ice up to 2,0 m thick, and capable of forcing the way continuously running in compact ice field up to 1,5 m thick. The total shaft power is not less than 11 mW)

LL8

Icebreaker category notation (intended for icebreaking operations: on coastal routes of the arctic seas in winter and spring with ice up to 3,0 m thick and in summer and autumn with no restrictions, and capable of forcing the way continuously running in compact ice field up to 2,0 m thick. The total shaft power is not less than 22 mW)

LL9

Icebreaker category notation (intended for icebreaking operations: in the arctic seas in winter and spring with ice up to 4,0 m thick and in summer and autumn with no restrictions, and capable of forcing the way continuously running in compact ice field up to 2,5 m thick. The total shaft power is not less than 48 mW)

LU1

Ice strengthening notation of the ship (independent navigation in small open ice in the non-arctic seas, short period, and in compact ice up to 0,4 m thick in a navigable passage astern an icebreaker)

LU2

Ice strengthening notation of the ship (independent navigation in small open ice in the non-arctic seas and in compact ice up to 0,55 m thick in a navigable passage astern an icebreaker)

LU3

Ice strengthening notation of the ship (independent navigation in small open ice in the non-arctic seas and in compact ice up to 0,7 m thick in a navigable passage astern an icebreaker)

LU4

Ice strengthening notation of the ship (independent navigation in young open arctic ice up to 0,6 m thick in winter and spring, and up to 0,8 m thick in summer and autumn. Navigation in a navigable passage astern an icebreaker in young arctic ice up to 0,7 m thick in winter and spring, and up to 1,0 m thick in summer and autumn)

LU5

Ice strengthening notation of the ship (independent navigation in young open arctic ice up to 0,8 m thick in winter and spring, and up to 1,0 m thick in summer and autumn. Navigation in a navigable passage astern an icebreaker in young arctic ice up to 0,9 m thick in winter and spring, and up to 1,2 m thick in summer and autumn)

LU6

Ice strengthening notation of the ship (independent navigation in young open arctic ice up to 1,1 m thick in winter and spring, and up to 1,3 m thick in summer and autumn. Navigation in a navigable passage astern an icebreaker in young arctic ice up to 1,2 m thick in winter and spring, and up to 1,7 m thick in summer and autumn)

LU7

Ice strengthening notation of the ship (independent navigation in young close arctic ice up to 1,4 m thick in winter and spring, and up to 1,7 m thick in summer and autumn with short ramming rammer of ice ridges. Navigation in a navigable passage astern an icebreaker in young arctic ice up to 2,0 m thick in winter and spring, and in biennial arctic ice up to 3,2 m thick in summer and autumn)

LU8

Ice strengthening notation of the ship (independent navigation in close young and biennial arctic ice up to 2,1 m thick in winter and spring, and up to 3,1 m thick in summer and autumn. Ramming rammer of ice ridges. Navigation in a navigable passage astern an icebreaker in biennial arctic ice up to 3,4 m thick in winter and spring, and in perennial ice in summer and autumn with no restrictions)

LU9

Ice strengthening notation of the ship (independent navigation in close perennial arctic ice up to 3,5 m thick in winter and spring, and up to 4,0 m thick in summer and autumn. Ramming rammer of ice ridges. Short ramming rammer of the young and biennial close ice segments)



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