IMO Polar Code (Categories A, B & C), PWOM, 5-Day Survival & Sub-Zero Winterisation Checklist

Under SOLAS Chapter XIV and the International Code for Ships Operating in Polar Waters (Polar Code, IMO Resolutions MSC.385(94) and MEPC.264(68)), every ship operating in Arctic waters or the Antarctic Area is classified into one of three categories and must hold on board both a Polar Ship Certificate and an approved Polar Water Operational Manual (PWOM):

• Polar Ship Certificate (Polar Code Part I-A § 1.3): Issued by the Administration or Recognized Organization after initial or renewal survey, recording the ship’s Category (A, B or C), Ice Class, Polar Service Temperature (PST) (if operating in low air temperatures), maximum expected time of rescue (≥ 5 days), and ice/temperature operational limitations.
• Polar Water Operational Manual — PWOM (Polar Code Part I-A Ch. 2): Must be carried on the bridge and contain ship-specific risk-based procedures for: (1) evaluating ice conditions using the POLARIS (Polar Operational Limit Assessment Risk Indexing System) Risk Index Outcome (RIO ≥ 0 for normal operation, or reduced-speed elevated risk for -10 ≤ RIO < 0 where permitted); (2) operating machinery, fire-fighting and life-saving systems in sub-zero temperatures; (3) icebreaker assistance and convoy towing procedures; and (4) joint SAR coordination and 5-day survival response.

Ships operating in polar waters where the Mean Daily Low Temperature (MDLT) is below -10°C must be certified for a Polar Service Temperature (PST) set at least 10°C below the lowest MDLT of the intended area and season (Part I-A § 1.2.11):

• Intact Stability under Ice Accretion (Polar Code Part I-A Ch. 4 § 4.3.1): Stability calculations for ships subject to icing must include the following statutory ice-accretion allowance:
  • 30 kg/m² on exposed weather decks and gangways;
  • 7.5 kg/m² for the projected lateral area of each side of the ship above the water plane; and
  • The projected lateral area of discontinuous surfaces of rail, sundry booms, spars (except masts) and rigging of ships having no sails, as well as the projected lateral area of other small objects, increased by 5% (lateral area) and 10% (static moments of this area).
• Fire Safety & Protection against Freezing (Part I-A Ch. 7): Isolating and pressure/vacuum valves in exposed locations must be protected from icing; two-way portable radios and fire-fighter’s outfits must be rated for low temperatures; fire pumps, sea chests and exposed fire mains must be fitted with trace heating or permanent draining/circulation arrangements so water cannot freeze in the fire line.
• Life-Saving Appliances & ≥ 5-Day Survival Equipment (Part I-A Ch. 8): Survival craft must be partially or totally enclosed (open lifeboats are prohibited in low air temperatures) with engine, fuel and battery systems rated to start at the PST. For the Maximum Expected Time of Rescue (never less than 5 days / 120 hours, § 1.2.7), the ship must carry: (1) an insulated immersion suit or thermal protective aid for 100% of persons on board; (2) Personal Survival Kits (PSK) for every person on board (protective outer clothing, head/neck/face protection, mittens/gloves, insulated waterproof footwear, snow goggles, survival candle, matches, whistle, drinking mug, penknife, survival handbook and carry bag); and (3) Group Survival Kits (GSK) providing shelter (tents/storm shelters) for 110% of persons, thermal sleeping bags/mats, stoves/fuel, water-purification or snow-melting equipment, flares, torches and rations providing sufficient energy for at least 5 days.

High latitudes degrade magnetic compass horizontal force and cause standard gyrocompass settling errors above 70°–80° latitude. Under Polar Code Part I-A Chapters 9, 11 and 12 (and Chapters 9-1 and 11-1 added by IMO Resolution MSC.532(107) effective 1 January 2026 for non-SOLAS cargo ships 300–499 GT, fishing vessels ≥ 24 m and pleasure yachts ≥ 300 GT):

• Mandatory Polar Navigation Equipment (Ch. 9): Ships must have a means of receiving and displaying current ice and meteorological information (§ 9.3.1); two independent echo-sounding devices or one device with two separate transducers on ships constructed on or after 1 Jan 2017 (§ 9.3.2.1.3); two remotely rotatable narrow-beam searchlights controllable from the bridge on ships operating in low light/ice (§ 9.3.3.2); manually or automatically controlled red flashing Rearward Ice Escort Light on ships involved in icebreaking operations (§ 9.3.3.3); and, when proceeding to latitudes over 80°, at least two non-magnetic means to determine and display heading and at least two independent GNSS receivers (§ 9.3.2.2).
• Polar Voyage Planning (Ch. 11): The Master’s berth-to-berth passage plan must incorporate the PWOM limitations, current and historical ice charts, places of refuge, remoteness from SAR facilities, and protective measures around marine mammals and national parks (§ 11.3).
• STCW Regulation V/4 & Code Section A-V/4 Polar Waters Training (Ch. 12): In open waters inside the polar boundary, the Master, Chief Mate and Officers in Charge of a Navigational Watch must hold a Certificate of Proficiency in Basic Training for Ships Operating in Polar Waters (or as specified in Table 12.1). In any ice concentration above 0/10 (other than ice-free waters), the Master and Chief Mate must hold Advanced Training for Ships Operating in Polar Waters and the OOW must hold Basic Training (§ 12.3.1).

Polar Code Part II-A imposes strict pollution-prevention rules in Arctic and Antarctic waters that override standard open-ocean MARPOL discharge thresholds:

Even outside Polar Code boundaries — such as winter calls in the Gulf of Bothnia, Gulf of Finland, St. Lawrence Seaway, Sakhalin, Bohai Bay or Alaska — port state inspectors and vetting auditors check that sub-zero winterisation procedures are executed before ambient temperatures drop below 0°C:

• Deck & Fire/Foam Mains: Isolate and drain exposed freshwater lines, deck air lines and non-heated fire-main branches (leaving dry-pipe drain cocks cracked or maintaining continuous circulation/trace heating); verify glycol/antifreeze protection on deck decontamination showers and eyewash stations; cover windlasses, mooring winches, P/V valves, whistle air lines and accommodation ladder winches with canvas ice covers; and stock rock salt/urea, wooden mallets and non-sparking de-icing shovels.
• Lifeboats, Rescue Boats & Liferafts: Verify that lifeboat engine coolant is tested to at least -30°C (or the ship’s PST), fuel tanks are filled with winter-grade Arctic diesel (CFPP rated for ambient temperature), lifeboat freshwater rations have expansion headspace so containers do not burst, battery chargers and space heaters in enclosed lifeboats are energised, and hydrostatic release units (HRUs) and embarkation ladders are clear of ice.
• Bridge & Navigation Sensors: Switch on window heaters, clear-view screens, whistle heaters, radar scanner heaters and anemometer heaters; verify gyrocompass high-latitude speed/latitude error correction; and check emergency navigation light lamps.
• Engine Room, Sea Chests & Ballast Tanks: Switch engine-room sea suctions from high sea chest to low sea chest; line up warm cooling-water recirculation or low-pressure steam/compressed-air weed-clearing to sea chests to prevent frazil/slush ice choking; verify fuel-oil pour-point and cold-filter plugging point (CFPP) heating in service/settling tanks and emergency generator fuel tanks; and avoid filling pressed-up ballast tanks above 90–95% capacity in freezing conditions to allow for ice expansion.