page_title: Finnish-Swedish ice class
section_title: Definition and requirements
hierarchical_section_title: Finnish-Swedish ice class / Definition and requirements
caption_attribution_description: English: MT Mastera in Rotterdam harbour. IMO Number: 9235892 MMSI Number: 230945000 Callsign: OJKE Length: 252 m Beam: 44 m Deutsch: Der dieselelektrisch angetriebene Tanker MASTERA, in Japan 2003 gebaut, hat einen Tiefgang von 15,30 m. Es ist mit 64259 BRZ; Tragfähigkeit: 106206 tdw vermessen und besitzt eine Doppelhülle. Für die Eisfahrt hat das Schiff auch eine Brücke nach achtern.
context_page_description: 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 and Communications Agency and the Swedish Maritime Administration.
context_section_description: 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 ice class 3 for vessels that do not belong to any other class such as unpropelled barges and ships built of wood. The Finnish-Swedish ice classes are usually spelled with Roman numerals, e.g. IA, 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 1.0 metre (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 1.0, 0.8 and 0.6 metres (3.3, 2.6 and 2.0 ft) 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 strength of the ship's hull, propulsion system and steering gear must be adequate to allow safe operation in the presence of ice, and the rules provide tables and formulas to determine minimum scantlings and other design criteria for each ice class. The thickness of ice used as the basis of these calculations is sometimes mistaken for the minimum icebreaking capability requirement for the ice-classed vessel.
caption: Double acting ships capable of independent operation in ice, such as Mastera, could be eligible for the proposed new ice class 1A Super+.
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