Ice-class, a brief summary

With the surge in orders for ice-class tankers, an understanding of the who, why, when and where of ice-class classification is becoming more relevant to a growing number of shipowners. Basically, this classification will be a requirement for vessels trading in coastal states with seasonal or year-round ice-covered oceans and seas.

Specific oceans include the Baltic Sea, Arctic Ocean (both Russian and Canadian) and the Ohkotsk Sea. There are also ice class rules and regulations for commercial ship operations on inland lakes e.g. the Great Lakes and the Caspian Sea.

Philosophy of ice-class

Essentially this is:

l Safety of hull structure and propulsion train under ice interaction loading scenarios.

l Criteria for installed minimum propulsion power.

The criteria for installed propulsion power is dependent on the ice-class philosophy of the coastal state, e.g. the Finnish Swedish Ice Class Rules (FSICR) criteria are driven by the need for maintenance of ship speed in ice with an underlying objective of maintenance of continuity of trade during the winter season in the Baltic.

Sea ice categories

The two different ice categories are first-year ice, i.e. up to 120 cm thick and low ice-strength properties, and multi-year old ice, i.e. up to 3 m or more thick and high ice-strength properties. As a consequence of both thicker ice sheets as well as the higher strength of multi-year ice, a ship designed for operation in multiyear ice is substantially different in configuration from a first-year ice class ship.

It is interesting to note that, in the context of current commercial newbuilding orders, the FSICR have become the de facto standard for new tonnage.

The FSICR Rule set has evolved over the years (1971, 1985 and 2002) to its current highly developed state, with a further evolution being currently researched in a joint IACS/FMA (Finnish Maritime Administration) research

project.