Finnish-Swedish ice class
Encyclopedia
The Finnish-Swedish ice class is an ice class
assigned to a vessel operating in first-year ice in the Baltic Sea
and calling 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 Safety Agency (TraFi), which overtook the responsibilities of the Finnish Maritime Administration in 2010, and the Swedish Maritime Administration
.
assistance, for example "ice class 1A, 2000 DWT
". Finnish fairway dues, a system of fees charged for the use of sea lanes to cover the costs of management and icebreaker assistance, also depend on the vessels' ice class. Since ships of lower ice classes generally require more assistance during the winter months, their fairway dues are considerably higher than those of ships of the highest ice classes. For this reason the majority of ships regularly calling Finnish ports are built to the highest ice classes. In the beginning of 2008, 47% of the Finnish tonnage were of ice class 1A Super.
Many international classification societies
have incorporated the Finnish-Swedish ice class rules to their own rulebooks and offer ice class notations that are recognized by the Finnish and Swedish authorities. Since the ice class rules have been revised and amended several times over the years, a list of equivalent ice class notations is used to assign the correct official ice class for older vessels when they visit Finnish and Swedish ports. Although mainly used in the Baltic Sea, the Finnish-Swedish ice classes and the equivalent ice class notations from classification societies are sometimes used when discussing ships operating in other ice-infested seas of the world.
While the Finnish-Swedish ice classes can be assigned to icebreakers for the purpose of collecting fairway fees, they are intended primarily for merchant ships operating under icebreaker escort. Because the level of ice-strengthening in ships designed to operate independently in ice-infested waters, especially in the presence of multi-year ice, usually exceeds the requirements of the Finnish-Swedish ice class rules, the classification societies use different ice class notations, such as the IACS Polar ice classes
, for icebreakers. The two highest Finnish-Swedish ice classes, 1A and 1A Super, are somewhat equivalent to the two lowest Polar classes, PC7 and PC6, respectively.
s and ships built of wood. The Finnish-Swedish ice classes are usually spelled with roman numerals in official context and legislation.
Ships must fulfill certain design requirements in order to obtain the ice class from the Finnish and Swedish authorities. The design requirement for ice class 1A Super is a minimum speed of 5 knots in a broken brash ice channel with a thickness of 1 metres (3.3 ft) in the middle and a consolidated (refrozen) ice layer of 0.1 metres (3.9 in). Ice classes 1A, 1B and 1C have lower design requirements corresponding to non-consolidated ice channels with a thickness of 1 , in the middle, respectively. While the ice class rules provide equations to calculate the minimum engine power based on the ship's main dimensions and hull shape, more exact calculations or ice model tests resulting in lower minimum engine power can also be approved, but in such case the ice class can be revoked if the experience of the ship's performance in practice motivates this. In addition the ice strengthening of the ship's hull must be adequate to allow safe operation in open sea conditions corresponding to a level ice thickness not exceeding 1 m (3.3 ft) for ice class 1A Super, 0.8 m (2.6 ft) for 1A, 0.6 m (2 ft) for 1B and 0.4 m (1.3 ft) for 1C. Again the rules provide tables and formulas to determine the minimum scantlings of the hull. The latter requirement is sometimes mistaken for the minimum required icebreaking capability of the vessel.
Ice class
Ships with an Ice Class have a strengthened hull to enable them to navigate through sea ice.-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...
assigned to a vessel 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...
and calling Finnish
Finland
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...
or 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....
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 Safety Agency (TraFi), which overtook the responsibilities of the Finnish Maritime Administration in 2010, and 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...
.
Purpose
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 icebreakerIcebreaker
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, 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...
". Finnish fairway dues, a system of fees charged for the use of sea lanes to cover the costs of management and icebreaker assistance, also depend on the vessels' ice class. Since ships of lower ice classes generally require more assistance during the winter months, their fairway dues are considerably higher than those of ships of the highest ice classes. For this reason the majority of ships regularly calling Finnish ports are built to the highest ice classes. In the beginning of 2008, 47% of the Finnish tonnage were of ice class 1A Super.
Many 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 ice class notations that are recognized by the Finnish and Swedish authorities. Since the ice class rules have been revised and amended several times over the years, a list of equivalent ice class notations is used to assign the correct official ice class for older vessels when they visit Finnish and Swedish ports. Although mainly used in the Baltic Sea, the Finnish-Swedish ice classes and the equivalent ice class notations from classification societies are sometimes used when discussing ships operating in other ice-infested seas of the world.
While the Finnish-Swedish ice classes can be assigned to icebreakers for the purpose of collecting fairway fees, they are intended primarily for merchant ships operating under icebreaker escort. Because the level of ice-strengthening in ships designed to operate independently in ice-infested waters, especially in the presence of multi-year ice, usually exceeds the requirements of the Finnish-Swedish ice class rules, the classification societies use different ice class notations, such as the IACS Polar ice classes
Polar class
Polar class refers to the ice class assigned to a ship by a classification society. A Polar class ship refers to a ship for which a Polar class has been assigned....
, for icebreakers. The two highest Finnish-Swedish ice classes, 1A and 1A Super, are somewhat equivalent to the two lowest Polar classes, PC7 and PC6, respectively.
Definition and requirements
Ships of the highest Finnish-Swedish 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. However, even ships of the highest ice class are assumed to require icebreaker assistance from time to time. In addition there are ice class 2 for self-propelled 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 bargeBarge
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 and ships built of wood. The Finnish-Swedish ice classes are usually spelled with roman numerals in official context and legislation.
Ships must fulfill certain design requirements in order to obtain the ice class from the Finnish and Swedish authorities. The design requirement for ice class 1A Super is a minimum speed of 5 knots in a broken brash ice channel with a thickness of 1 metres (3.3 ft) in the middle and a consolidated (refrozen) ice layer of 0.1 metres (3.9 in). Ice classes 1A, 1B and 1C have lower design requirements corresponding to non-consolidated ice channels with a thickness of 1 , in the middle, respectively. While the ice class rules provide equations to calculate the minimum engine power based on the ship's main dimensions and hull shape, more exact calculations or ice model tests resulting in lower minimum engine power can also be approved, but in such case the ice class can be revoked if the experience of the ship's performance in practice motivates this. In addition the ice strengthening of the ship's hull must be adequate to allow safe operation in open sea conditions corresponding to a level ice thickness not exceeding 1 m (3.3 ft) for ice class 1A Super, 0.8 m (2.6 ft) for 1A, 0.6 m (2 ft) for 1B and 0.4 m (1.3 ft) for 1C. Again the rules provide tables and formulas to determine the minimum scantlings of the hull. The latter requirement is sometimes mistaken for the minimum required icebreaking capability of the vessel.