Ice class
Encyclopedia
Ship
s with an Ice Class have a strengthened hull
to enable them to navigate through sea ice
.
and the IMO
.
s (aggregate of girders, beams, and bulkheads resulting in stronger structural integrity) must be in place. Sea chests (openings in the hull for seawater intake) 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 pintle
s 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.
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.
The ABS database includes hundreds of Arctic Ice Classed ships, including many Arctic Research Vessels, and the entire productions of certain shipyards.
-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 Safety Agency (TraFi). 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.
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 barge
s. The classes can also be spelled with roman numerals.
Traffic restrictions in the Baltic Sea during winter months are based on the Finnish-Swedish ice class. 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
".
published a set of Unified Requirements for Polar Class Ships to complement the IMO
Guidelines for Ships Operating in Arctic Ice Covered Waters. This will effectively unify the ice classes for all IACS member societies. Seven Polar Classes are proposed in the requirements, abbreviated as PC1 through PC7
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...
s with an Ice Class have a strengthened hull
Hull (watercraft)
A hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present. The line where the hull meets the water surface is called the waterline.The structure of the hull varies depending on the vessel type...
to enable them to navigate through sea ice
Sea ice
Sea ice is largely formed from seawater that freezes. Because the oceans consist of saltwater, this occurs below the freezing point of pure water, at about -1.8 °C ....
.
History
The first requirements for merchant ships to be escorted by icebreakers were set in Finland in 1890, after winter traffic to the port of Hanko was started. In the past, different classification organizations had different standards, rules, and ice classes. Converting between the Baltic and Arctic systems is not usually done. Recently, the two different class systems have been defined by the IACSInternational Association of Classification Societies
The International Association of Classification Societies is a technically-based organization consisting of thirteen marine classification societies headquartered in London.-History:...
and the IMO
International Maritime Organization
The International Maritime Organization , formerly known as the Inter-Governmental Maritime Consultative Organization , was established in Geneva in 1948, and came into force ten years later, meeting for the first time in 1959...
.
Significance of Ice Class
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 scantlingScantling
Scantling is a measurement of prescribed size, dimensions, or cross sectional areas. For comparison, see Form Factor: -Shipping:In shipbuilding, the scantling refers to the collective dimensions of the various parts, particularly the framing and structural supports. The word is most often used in...
s (aggregate of girders, beams, and bulkheads resulting in stronger structural integrity) must be in place. Sea chests (openings in the hull for seawater intake) 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 pintle
Pintle
A pintle is a pin or bolt, usually inserted into a gudgeon, which is used as part of a pivot or hinge.A pintle/gudgeon set is used in many spheres, for example: in sailing to hold the rudder onto the boat; in transportation a pincer-type device clamps through a lunette ring on the tongue of a...
s 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.
Arctic classes
The American Bureau of ShippingAmerican Bureau of Shipping
The American Bureau of Shipping is a classification society, with a mission to promote the security of life, property and the natural environment, primarily through the development and verification of standards for the design, construction and operational maintenance of marine-related facilities...
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
Classification society
A classification society is a non-governmental organization that establishes and maintains technical standards for the construction and operation of ships and offshore structures...
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.
The ABS database includes hundreds of Arctic Ice Classed ships, including many Arctic Research Vessels, and the entire productions of certain shipyards.
Finnish-Swedish ice class
In the FinnishFinland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
-Swedish
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
ice class rules merchant ships operating in first-year ice in the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...
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
Swedish Maritime Administration
The Swedish Maritime Administration is the Swedish government agency which provides services to the transport sector by keeping the sea lanes open and safe...
and the Finnish Transport Safety Agency (TraFi). International classification societies
Classification society
A classification society is a non-governmental organization that establishes and maintains technical standards for the construction and operation of ships and offshore structures...
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.
Ships of the highest ice class, 1A Super, are designed to operate in difficult ice conditions mainly without icebreaker
Icebreaker
An icebreaker is a special-purpose ship or boat designed to move and navigate through ice-covered waters. Although the term usually refers to ice-breaking ships, it may also refer to smaller vessels .For a ship to be considered an icebreaker, it requires three traits most...
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 barge
Barge
A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. Some barges are not self-propelled and need to be towed by tugboats or pushed by towboats...
s. The classes can also be spelled with roman numerals.
Traffic restrictions in the Baltic Sea during winter months are based on the Finnish-Swedish ice class. 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
Deadweight tonnage
Deadweight tonnage is a measure of how much weight a ship is carrying or can safely carry. It is the sum of the weights of cargo, fuel, fresh water, ballast water, provisions, passengers, and crew...
".
IACS Polar Classes
The International Association of Classification SocietiesInternational Association of Classification Societies
The International Association of Classification Societies is a technically-based organization consisting of thirteen marine classification societies headquartered in London.-History:...
published a set of Unified Requirements for Polar Class Ships to complement the IMO
International Maritime Organization
The International Maritime Organization , formerly known as the Inter-Governmental Maritime Consultative Organization , was established in Geneva in 1948, and came into force ten years later, meeting for the first time in 1959...
Guidelines for Ships Operating in Arctic Ice Covered Waters. This will effectively unify the ice classes for all IACS member societies. Seven Polar Classes are proposed in the requirements, abbreviated as PC1 through PC7