Extended Operational and Trade Vocabulary

Polar Code, Ice Navigation and Polar Operations glossary

The Polar Code and ice-navigation vocabulary: Category A, B, and C ships, acceleration ice loads, the ice services (AARI) and ice charts, the Admiralty Arctic Pilot publications, and the survival, structural, and operational requirements for polar waters. Grounds each term in the Polar Code chapter or the ice-navigation practice it depends on.

499 defined terms.

Showing 250 on this page (page 1 of 2).

A

A-class ship (Polar Code): Category A ship designed for operation in polar waters in at least medium first-year ice, which may include old ice inclusions.
AARI: Arctic and Antarctic Research Institute, St Petersburg; Russian national ice service producing Arctic ice charts and forecasts.
Acceleration ice load: Dynamic load on hull from ice impact during ramming or transit through pack ice.
Admiralty Sailing Directions NP11: Arctic Pilot Volume 1; UKHO publication covering general remarks on Arctic navigation.
Admiralty Sailing Directions NP12: Arctic Pilot Volume 2; covers Greenland and Canadian Arctic waters.
Admiralty Sailing Directions NP13: Arctic Pilot Volume 3; covers eastern Arctic and Russian sectors.
Aker ARC 100: Aker Arctic conceptual icebreaking shuttle tanker design used for Arctic oil export trades.
Aker ARC 121: Design basis for the Norilsk Nickel ice-class container ships such as Norilskiy Nickel.
Aker ARC 130A: Design used for the Yamal LNG Arc7 ice-class LNG carriers (Christophe de Margerie class).
Aker ARC design series: Family of double-acting icebreaking ship designs by Aker Arctic Technology, Finland.
Algae bloom (under-ice): Spring biological production beneath sea ice, key to polar food web.
Allision (ice): Contact between a moving ship and a stationary ice feature such as fast ice or grounded berg.
Ambient air temperature: Outside air temperature; Polar Code requires materials and equipment rated to Polar Service Temperature.
Anchor ice: Submerged ice attached to the seabed in shallow polar waters.
Antarctic Convergence: Frontal zone where cold Antarctic surface water meets warmer subantarctic water.
Antarctic Peninsula: Region of frequent IAATO tourist operations and dense ice navigation traffic.
Antarctic Special Area (MARPOL Annex I): Designation under MARPOL Annex I prohibiting oil discharge in Antarctic waters south of 60 degrees S.
Antarctic Treaty (1959): International agreement reserving Antarctica for peaceful and scientific use; entered into force 1961.
Antarctic Treaty Consultative Meeting (ATCM): Annual meeting of Antarctic Treaty parties adopting measures, decisions, and resolutions.
Antarctic Treaty System (ATS): Collective of the Antarctic Treaty plus protocols including the Madrid Protocol and CCAMLR.
Arc4 (RMRS): Russian Maritime Register of Shipping ice class for independent navigation in first-year Arctic ice up to 0.6 m winter or 0.8 m summer.
Arc5 (RMRS): RMRS ice class for independent navigation in first-year Arctic ice up to 0.8 m winter or 1.0 m summer.
Arc6 (RMRS): RMRS ice class for independent navigation in first-year Arctic ice up to 1.1 m winter or 1.3 m summer.
Arc7 (RMRS): RMRS ice class for independent navigation in first-year Arctic ice up to 1.4 m winter or 1.7 m summer; used by Yamal LNG fleet.
Arc8 (RMRS): RMRS ice class for independent navigation in multi-year Arctic ice up to 2.1 m.
Arc9 (RMRS): Highest RMRS Arctic ice class for independent navigation in heavy multi-year ice exceeding 3.5 m.
Arctic (Polar Code definition): Waters north of latitude 60 degrees N, excluding the Norwegian Sea south of 65 degrees N and waters below Iceland as defined in SOLAS XIV.
Arctic Bridge: Seasonal sea route between Murmansk and the Port of Churchill, Hudson Bay.
Arctic Council: Intergovernmental forum of eight Arctic states established by the 1996 Ottawa Declaration.
Arctic Council PAME: Protection of the Arctic Marine Environment working group; author of the Arctic Marine Shipping Assessment.
Arctic Marine Shipping Assessment (AMSA 2009): PAME report mapping Arctic shipping activity and risks; preceded the Polar Code.
Arctic Ocean: Smallest of the world's oceans, largely ice-covered, surrounded by Eurasia and North America.
Arctic Search and Rescue Agreement (2011): Arctic Council binding agreement on cooperation in SAR signed in Nuuk.
Areas to be Avoided (ATBA): IMO ships' routeing measure under SOLAS V/10; used for the Aleutian Islands and Bering Strait.
Argos system: Satellite-based location and data collection system used for ice-drifter buoys.
Astern operation (DAS): Operation of double-acting ships stern-first to break heavier ice.
ATCM Measure: Legally binding instrument adopted at ATCM and ratified by Consultative Parties.
Atomflot: Rosatomflot, Russian operator of the world's only fleet of nuclear-powered civilian icebreakers.

B

B-class ship (Polar Code): Category B ship designed for operation in at least thin first-year ice, which may include old ice inclusions.
Backing and ramming: Icebreaking technique involving repeated reversing and forward thrusts to break heavy ice.
Baffin Bay: Body of water between Greenland and Baffin Island connected to the Labrador Sea.
Baffin Bay/Davis Strait NAFO area: Fisheries management area relevant to ice-edge operations.
Baltic ice classes: Common name for the Finnish-Swedish Ice Classes IA Super through III.
Barents Sea: Shelf sea of the Arctic Ocean north of Norway and Russia.
Basic polar training (STCW V/3): Mandatory polar training for masters, chief mates and officers in charge of a navigational watch on ships in polar waters.
Beaufort Sea: Arctic sea north of Alaska and northwestern Canada, heavy multi-year ice region.
Beaufort Sea Gyre: Wind-driven clockwise current that accumulates and recirculates Arctic sea ice.
Bergy bit: Piece of glacier ice between 1 and 5 m above sea level and 100 to 300 sq m in area.
Bergy water: Open water with floating bergy bits and growlers but no sea ice present.
Bering Sea: Marginal sea between Alaska and Siberia, hosting major pollock and crab fisheries.
Bering Strait: Narrow passage connecting the Pacific and the Arctic Ocean between Russia and Alaska.
Bering Strait Voluntary Two-Way Route: IMO-adopted voluntary routeing measure (2018) establishing two-way routes and ATBAs.
Black carbon (BC): Sooty particulate emission from marine diesel; deposition on ice accelerates melt.
Block coefficient (ice): Relevant to icebreaking resistance and hull form design for polar service.
Bollard pull (icebreaker): Static towing pull; used to size icebreakers for assistance and escort.
Bow form (icebreaker): Specially shaped bow such as spoon bow or Thyssen-Waas to ride up on and break ice.
Brash ice: Accumulation of floating ice fragments not more than 2 m across, the wreckage of other ice forms.
Bridge equipment (Polar Code): Requirements in Polar Code Chapter 9 for equipment performance at Polar Service Temperature.
Bridge windows (Polar Code): Must be heatable and provide clear view for ice navigation per Polar Code 9.3.
Bulk carrier (Polar Class): Cargo ship constructed to a Polar Class to operate in Arctic seasonal trades such as Baffinland Mary River iron ore.

C

CAA (Canadian Arctic Archipelago): Group of islands forming the Canadian sector of the Arctic Ocean.
Canadian Coast Guard Icebreaker fleet: Operator of medium and heavy icebreakers in the Canadian Arctic and Gulf of St Lawrence.
Canadian Ice Service (CIS): Branch of Environment and Climate Change Canada producing Canadian ice charts.
Cape Dezhnev: Easternmost point of mainland Russia, northern entrance to the Bering Strait.
Capella Space: Commercial SAR satellite operator providing X-band imagery used for sea ice monitoring.
Cargo tanks (Polar Code): Cargo tanks in Category A and B oil tankers must not be located against the shell plating.
Category A ship: Polar Code ship designed for operation in at least medium first-year ice, which may include old ice inclusions.
Category B ship: Polar Code ship designed for operation in at least thin first-year ice, which may include old ice inclusions.
Category C ship: Polar Code ship designed for operation in open water or in less severe ice conditions than Categories A or B.
CCAMLR: Commission for the Conservation of Antarctic Marine Living Resources.
CCAMLR Convention Area: Waters south of the Antarctic Convergence regulated for fisheries by CCAMLR.
Certificate of Polar Ship: Polar Ship Certificate issued by Administration or RO certifying compliance with Polar Code Part I-A.
Chukchi Sea: Marginal sea of the Arctic Ocean north of the Bering Strait.
CIRM: Comite International Radio-Maritime, marine electronics industry body.
Clean ice: Sea ice with low sediment content, common offshore.
Close pack ice: Sea ice concentration 7/10 to 8/10 with floes mostly in contact.
CO2 fixed system (Polar Code): Fire-fighting medium must remain effective at the Polar Service Temperature.
Code for Ships Operating in Polar Waters: Full name of the Polar Code.
Cold-rated equipment: Equipment qualified to operate at the Polar Service Temperature.
Compacted ice: Ice pack compressed and concentrated by wind or current.
Compass deviation (high latitude): Larger and more variable magnetic deviation due to proximity to magnetic poles.
Compulsory ice pilot: Ice pilot required for certain Russian NSR voyages depending on POLARIS outcome and ship class.
Concentration (ice): Ratio in tenths of the sea surface covered by ice within a defined area.
Concentration boundary (WMO): Boundary on an ice chart separating areas of different concentration.
Consolidated ice: Floating ice frozen together into a single sheet.
Convergence (ice): Wind- or current-driven compression of an ice pack.
Convoy operations: Group of ships escorted through ice by one or more icebreakers in line astern.
Corrosion (cold climate): Reduced corrosion rates of steel in polar service but enhanced cracking risk at low temperature.
Crew familiarization (Polar Code): All crew must be familiar with operational procedures appropriate to polar conditions.
Crystal Endeavor: Polar-class expedition cruise ship built to PC6 standards (2021).
Cup anemometer (heated): Heated wind sensor used on polar-rated vessels to prevent icing.

D

Daily ice chart: Operational chart issued by national ice services such as CIS or Norwegian Ice Service.
DAS (double-acting ship): Ship designed to run ahead in open water and astern in heavy ice; flat-stem stern acts as icebreaking bow.
Davis Strait: Strait between Greenland and Baffin Island.
Decks and superstructure (icing): Subject to topside icing requiring removal in cold weather operations.
Deformed ice: Ice piled up by pressure into ridges, rafts, or hummocks.
Deicing equipment (Polar Code): Means to remove ice accretion required by Polar Code Part I-A Chapter 3.
Denmark Strait: Strait between Greenland and Iceland, southern boundary of the Polar Code Arctic area.
Derived ice multiplier (POLARIS RIO): Numerical value assigned to each ice type for the POLARIS calculation.
Detection of ice (radar): Use of X-band radar at short range to detect growlers and bergy bits.
Direct calculation (PC): First principles structural design method allowed in addition to IACS UR I formulas.
Disko Bay: Bay on the west coast of Greenland; calving ground for icebergs from Jakobshavn Glacier.
Distress sequence (polar): Emergency communication considering reduced GMDSS coverage above 70 degrees N.
Diversion plan (Polar Code): Voyage planning element to account for limited places of refuge.
Double-acting tanker (DAT): Tanker with DAS design used in Russian Arctic crude oil export from Varandey.
Drift Ice: Sea ice not attached to the shore, drifting with winds and currents.
Drifting station: Russian and US programs operating manned ice stations on multi-year floes from the 1930s onward.
Dual-fuel engines (polar): Engines burning LNG and MGO used on Arctic LNG carriers to comply with HFO restrictions.
Dynamic positioning (ice): DP operation in ice requires special equipment classes and ice management.

E

Earth observation (ice): Use of satellite imagery for sea ice monitoring and tactical navigation.
East Greenland Current: Cold southward current carrying Arctic water along Greenland's east coast.
East Siberian Sea: Marginal sea of the Arctic Ocean north of eastern Siberia; key NSR segment.
Egg Code: WMO ice chart symbology representing concentration, stage of development, and floe size in an oval form.
EHN (Emergency Towing): Emergency towing arrangements considered under Polar Code for tanker assistance.
Elevated walkways (icing): Required to be kept clear of ice accretion during cold weather operations.
EMSA Arctic studies: European Maritime Safety Agency publications on Arctic shipping risk.
Encounter speed (ice): Speed at which the bow contacts ice; key input for ice load assessment.
EOSR (escape, evacuation and rescue): Polar Code Chapter 8 requirements; equipment must function in expected maximum expected time of rescue.
Equivalent ice thickness: Ice thickness used in POLARIS multiplier tables for mixed ice conditions.
Escort (icebreaker): Service provided by an icebreaker leading one or more ships through ice.
Evacuation time (Polar Code): Rescue equipment must support at least 5 days of survival.
Exhaust gas (cold): Stack emissions condense rapidly in cold air; visible plume management.
Expedition cruise vessel: Polar-class passenger ship for Arctic and Antarctic tourism; IAATO-regulated in Antarctica.
Extended polar code: Informal reference to Phase 2 work on non-SOLAS vessels (fishing, pleasure, cargo under 500 GT).

F

Fairway ice: Ice in a navigable channel maintained by icebreakers.
Fast Ice: Sea ice frozen to the shore.
Finger rafting: Interlocking thrusting of floes one over the other in alternating fingers, typical of nilas.
Finnish Maritime Administration: Source of Finnish-Swedish Ice Class Rules together with Swedish Maritime Administration.
Finnish Meteorological Institute (FMI): National ice service for the Baltic Sea, issuing daily ice charts.
Finnish-Swedish Ice Class IA: ice class for navigation in severe ice with occasional icebreaker assistance.
Finnish-Swedish Ice Class IA Super: highest Finnish-Swedish ice class for navigation in difficult Baltic ice without icebreaker assistance.
Finnish-Swedish Ice Class IB: ice class for navigation in medium ice with icebreaker assistance.
Finnish-Swedish Ice Class IC: ice class for navigation in light ice with icebreaker assistance.
Finnish-Swedish Ice Class II: notation for steel ships of normal design suited only to very light ice.
Finnish-Swedish Ice Class III: notation for ships not meeting II requirements.
Fire-fighting (Polar Code): Foam, water, and dry chemical systems must be designed for Polar Service Temperature.
First-Year Ice: Sea ice that has not survived a melt season.
First-year ice medium: First-year ice 70 to 120 cm thick.
First-year ice thick: First-year ice greater than 120 cm thick.
First-year ice thin: First-year ice 30 to 70 cm thick.
Flaw: Narrow separation zone between pack ice and fast ice where floes can move freely.
Flaw lead: Lead between pack ice and fast ice, navigable in season.
Floe: Individual piece of sea ice.
Floe size: WMO classification small (20 to 100 m), medium, big, vast, giant.
Floeberg: Massive piece of sea ice up to 5 m above the surface, formed by ridging and weathering.
Forecast ice: Predicted ice distribution issued by national ice services or commercial providers.
Fram Strait: Passage between Greenland and Svalbard, the main deep connection between Arctic and Atlantic.
Frame spacing (PC): Reduced for polar-class ships per IACS UR I to limit ice plate stresses.
Franz Josef Land: Russian high-Arctic archipelago in the Barents Sea.
Frazil ice: Fine spicules or plates of ice suspended in water; first stage of sea ice formation.
Free-fall lifeboat (polar): Lifeboat design considered for polar service with thermal protection.
Freezing rain: Rain that freezes on contact, leading to severe topside icing.
Fuel oil (Polar Code Part II-A): Operational discharge of oil prohibited in polar waters.

G

Garbage management (Polar Code): Polar Code Part II-A prohibits discharge of garbage in polar waters with limited exceptions per MARPOL Annex V.
Gas-fired heater: Used to keep deck machinery warm in polar service.
GIS (Greenland Ice Sheet): Continental ice sheet covering most of Greenland; principal North Atlantic iceberg source.
Glacier: Mass of land ice flowing under gravity, terminating on land or at tidewater.
Glacier ice: Ice originating from glaciers; structurally different from sea ice.
Glacier tongue: Long, narrow floating extension of a glacier projecting into the sea.
GMDSS A4: GMDSS sea area outside Inmarsat coverage, principally polar regions above 70 degrees N or S.
Government-mandated icebreaker fees: Charges levied by NSR Administration or Finnish authorities for icebreaker assistance.
Grease ice: Later stage of frazil coagulation, forming a soupy layer giving a matte appearance to the sea.
Great-circle routing (polar): Shortest path between two points; significant savings on Trans-Polar routes.
Grey ice: Young ice 10 to 15 cm thick, less elastic than nilas and breaking on swell.
Grey-white ice: Young ice 15 to 30 cm thick.
Group survival pack: Polar Code item providing food, water, shelter, and signalling for survivors during the maximum expected time of rescue.
Growler: Smaller piece of glacier ice less than 1 m above sea level, hazardous to navigation.
GZ curve (intact ice): Stability requirements must consider ice accretion topside weight per Polar Code Chapter 4.

H

Habitability (Polar Code): Requirements for cold weather protection of accommodation spaces.
Heavy fuel oil (HFO): Residual marine fuel, RMG 380, ISO 8217.
Heeling tank (icebreaker): Tank system that rapidly transfers ballast side to side to break stuck ice.
HFO Antarctic ban: MARPOL Annex I Regulation 43 prohibiting use and carriage of HFO south of 60 degrees S since 1 August 2011.
HFO Arctic ban: MARPOL Annex I Regulation 43A prohibiting use and carriage of HFO in Arctic waters; entered force 1 July 2024.
HFO Arctic waiver: Conditional exemption for Arctic coastal state flagged ships permitted until 1 July 2029.
Hindcast ice: Reanalysis of historical ice conditions for design and route planning.
Hummock: Hillock of broken ice forced up by pressure, weathered with time.
Hummocked ice: Ice piled up haphazardly by pressure into a chaotic surface.
Hydrography (polar): Sparse hydrographic survey coverage in many Arctic waters; SOLAS V/9 considerations.
Hydrostatic release: HRU for liferafts must function at Polar Service Temperature.

I

IAATO: International Association of Antarctica Tour Operators, founded 1991; self-regulates Antarctic tourism.
IACS UR I: Unified Requirements for Polar Class ships covering structural and machinery design.
IACS UR I1: Polar Class descriptions PC1 through PC7.
IACS UR I2: Structural requirements for polar class ships.
IACS UR I3: Machinery requirements for polar class ships.
IBRV (icebreaking research vessel): Polar research ship combining icebreaking and scientific capability.
ICC (Inuit Circumpolar Council): Inuit representative organization for Greenland, Canada, Alaska, and Chukotka.
ICCT Arctic shipping reports: International Council on Clean Transportation studies on Arctic emissions including black carbon.
Ice accretion: Build-up of ice on exposed surfaces from spray or precipitation; Polar Code requires removal means.
Ice advisor: Person providing tactical ice advice to the bridge team during ice passages.
Ice atlas: Compilation of monthly ice statistics for a region.
Ice belt: Strengthened plating around the waterline of an ice-class ship.
Ice blink: Whitish glare on the underside of clouds indicating presence of ice.
Ice boom: Floating barrier used to manage ice flow at hydroelectric or port installations.
Ice cake: Floe less than 20 m across.
Ice canopy: Underside of sea ice as seen from below, navigated by submarines.
Ice cap: Dome-shaped ice mass smaller than 50,000 sq km covering a highland area.
Ice cap (polar): Permanent ice cover at the geographic poles.
Ice chart: Map showing distribution, concentration, and type of sea ice.
Ice Class: Hull classification for ships operating in ice.
Ice concentration: Areal fraction of the sea surface covered by ice, reported in tenths or eighths.
Ice cover: General term for area of sea covered by ice of any type.
Ice damage: Hull damage from ice contact; principal failure mode is plate denting between frames.
Ice density: Approximately 920 kg per cubic meter for pure ice; lower for sea ice with brine inclusions.
Ice detection radar: X-band radar with high range and angular resolution for detecting growlers and bergy bits.
Ice edge: Boundary between open water and sea ice, often biologically productive.
Ice field: Area of pack ice 10 km or more across.
Ice floe: See floe.
Ice forecast: Prediction of ice extent, concentration, and drift issued by national ice services.
Ice fraction: Synonym for ice concentration.
Ice imaging: Acquisition of ice maps from SAR and optical satellites.
Ice information (Polar Code): PWOM must address how ice information is acquired and used.
Ice keel: Downward projecting mass of broken ice below a ridge, hazardous to subsea infrastructure.
Ice load: Force on hull from ice contact; design parameter under IACS UR I.
Ice management: Combined use of icebreaker support, scouting, and route selection in ice operations.
Ice navigator: STCW V/3 trained officer with advanced training; provides ice navigation watchkeeping.
Ice navigator competence: Demonstrated through certificate of proficiency in advanced training in ice navigation.
Ice pilot: Local pilot with ice knowledge; required in certain Canadian and Russian waters.
Ice rind: Brittle shiny crust of ice on a quiet sea surface up to 5 cm thick.
Ice routing: Selection of route through or around ice to minimize risk and time.
ICE-CR (cold region): Generic class notation for cold-region operation.
Iceberg: Mass of ice broken from a glacier and floating in the sea.
Iceberg census: Counting and tracking of icebergs in a region, principally by IIP off Newfoundland.
Iceberg drift: Movement of an iceberg under wind, current, and Coriolis force.
Icebreaker: Vessel designed to navigate ice-covered waters.
Icebreaker assistance: Service of icebreaker leading or freeing a ship in ice.
Icebreaker bow: Specially designed bow form for icebreaking, such as wedge, spoon, or Thyssen-Waas.
Icebreaker6 (RMRS): Russian Maritime Register icebreaker ice class equivalent to small port icebreakers.
Icebreaker7 (RMRS): RMRS class for medium icebreakers, e.g. Kapitan Sorokin class.
Icebreaker8 (RMRS): RMRS class for heavy linear icebreakers, e.g. Taymyr class nuclear.
Icebreaker9 (RMRS): RMRS class for heaviest icebreakers, e.g. Arktika class and Project 22220 nuclear.
ICEYE: Finnish commercial SAR satellite operator providing sub-daily ice imagery.
IICWG: International Ice Charting Working Group, coordinating national ice services since 1999.
IIP (International Ice Patrol): USCG-managed service warning of iceberg danger in the North Atlantic since 1914.
Imager (visible): Optical satellite sensor used in cloud-free conditions for ice mapping.
IMO: International Maritime Organization, UN specialized agency for shipping safety, security, and pollution prevention.
IMO ATBA: Areas to Be Avoided adopted under SOLAS V/10.
IMO Resolution MEPC.264(68): Adopted the Polar Code environmental provisions, May 2015.
IMO Resolution MEPC.265(68): Amendments to MARPOL Annexes I, II, IV, V to make environmental provisions of Polar Code mandatory.
IMO Resolution MEPC.328(76): Revised MARPOL Annex VI; not Polar-Code specific but governs sulphur and other emissions.
IMO Resolution MSC.385(94): Adopted the Polar Code safety provisions, November 2014.
IMO Resolution MSC.386(94): Amendments to SOLAS adding new Chapter XIV to make Polar Code mandatory.
IMO Resolution MSC.387(94): Polar Code amendments to STCW for V/3 polar training.
Independent ice navigation: Navigation in ice without icebreaker assistance.
Industrial personnel (Polar Code): Considered in Polar Code 1.2 definitions for offshore service vessels.
Insulation (Polar Code): Required for accommodation and machinery spaces for cold weather service.
Internal waters (Arctic): Russian and Canadian claims to Arctic straits as internal waters affect transit rights.
International Ice Patrol: See IIP.
Inuit Circumpolar Council: Inuit indigenous body engaged with IMO on polar shipping issues.
Inundation (deck): Green water and spray contributing to topside icing.
Inverted echo sounder: Measures sea ice draft from below; used for in-situ keel measurement.