As winter sets in, cold surges and extratropical cyclones become frequent. From China’s coastal waters to the mid- and high-latitude areas of the North Atlantic and North Pacific, shipping faces multiple safety hazards including frequent gales, sharp temperature drops and sea ice formation. Winter is a critical period for global maritime safety management. In accordance with the requirements of the ship safety management system and practical experience in coastal and ocean-going shipping, this guideline sorts out core winter operational precautions from four dimensions: gale risk mitigation, equipment freeze protection, crew cold protection and special controls for high-latitude navigation. It covers nearshore and transoceanic voyages to help vessels navigate safely through winter.

Gale Mitigation: End-to-End Control from Forecasting to Field Practice

Winter gales feature long duration, strong gusts and high swell energy. Along China’s coast, northerly gales induced by cold waves are concentrated in impact areas and subside quickly. In the mid- and high-latitude North Atlantic and North Pacific, extratropical cyclones persist, bringing prolonged rough seas with greater destructive potential. For all navigation areas, the control principle of prevention first and dynamic adjustment shall be strictly followed.

1. Pre-voyage Weather Assessment and Route Optimization

• Tiered meteorological monitoring and evaluation: Ships shall continuously receive official weather forecasts, weather facsimiles and navigational warnings, and thoroughly analyse wind force, wave direction, swell height and trends over the intended route. For coastal voyages in China, focus on the arrival time of cold air, gale coverage and wind scale, and identify sheltered anchorages in advance. For ocean crossings across the North Atlantic and North Pacific, masters shall consult the ship management team for weather routing before departure to avoid the core paths of extratropical cyclones and persistent gale zones. The North Atlantic is dominated by the Icelandic Low in winter with dense storm tracks and far-propagating swells; extreme sea states may see wave heights of 8–10 metres. The North Pacific is controlled by the Aleutian Low, with persistent northerly winds in mid-high latitudes often accompanied by snow squalls and sudden visibility reduction. Route planning shall avoid high-latitude storm belts, adopt safer mid-latitude tracks, mark diversion points and emergency anchorages, and incorporate heavy weather response plans into the voyage plan.
• Full vessel securing and inspection: 48 hours before the arrival of heavy weather, complete all preparations against rough seas following the heavy weather checklist. All loose deck stores, lifeboats and rafts, gangways and fittings shall be securely lashed. Safety lifelines shall be fitted on deck passageways. Anchoring gear shall be stowed flush against the hull, anchor chains secured with safety wires, hawsepipe covers closed and fastened, and canvas wrapping applied where necessary to reduce green water shipping over the bow. All watertight doors, hatches and forecastle store openings shall be closed; the integrity of sealing gaskets shall be verified. Key machinery including main engine, steering gear, windlass and generator engines shall be checked, together with emergency power and communication equipment.

2. Navigation Operations in Gale Conditions

• Watchkeeping and command escalation: When wind reaches Force 7 and wave height is 4 metres or above, the master shall take direct command on the bridge with the main engine on standby. If auto-pilot cannot maintain heading, switch immediately to hand steering. Deck and engine room watchkeeping strength shall be reinforced to monitor machinery operation and hull watertight integrity. Rapid barometric pressure changes are common with winter storms in the two oceans; navigational officers shall record meteorological readings regularly, anticipate sea state evolution and report promptly to the master.
• Scientific adjustment of heading and speed:
  • Head sea: Reduce speed appropriately and maintain a heading around 30° relative to the sea to mitigate pitching and slamming. For prolonged head-sea navigation, alternate the sea between port and starboard sides to avoid persistent hogging/sagging and propeller racing. Swell periods are long in winter across the North Atlantic and North Pacific, causing severe hull slamming. Speed must be controlled to prevent excessive bow shipping which may damage deck fittings and overstress hull structures.
  • Following sea: Control vessel speed to avoid overtaking by waves, which causes heavy stern shipping. Avoid large rudder angles to prevent loss of stability and broaching.
  • Heaving-to and drifting: If sea conditions make headway impracticable, heave-to to hold position while riding out the storm. If drifting is unavoidable, fully assess surrounding hazards and keep clear of shoals, reefs and dense traffic areas.
• Rules for cyclone evasion: When encountering a rapidly developing extratropical cyclone, continuously track barometric pressure and wind shifts to determine the vessel’s position relative to the cyclone. In the Northern Hemisphere: if in the dangerous right semicircle, keep the bow on the starboard bow and make best speed to escape; if in the left semicircle or in the cyclone track, keep the stern on the starboard quarter and navigate away from the hazard zone.
• Turning and avoidance principle: Manoeuvres to turn round shall be avoided in heavy weather. If turning is necessary, observe wave cycles and execute during the calm interval between large waves. Never allow the sea to strike abeam. Turning from following sea to head sea carries higher risk, especially for light-displacement vessels. Brief additional engine power may be used if needed to improve rudder effectiveness.

3. Anchorage and Berthing Under Gale Conditions

• Anchorage control: Select anchorages with adequate depth and good shelter to avoid insufficient under-keel clearance caused by swells. In rough weather, lay two anchors and increase scope, with main engine on standby. Monitor anchor position continuously using radar and GNSS to detect dragging. If dragging occurs, use engine and rudder to ease chain loads and proceed to safe waters if required. Open, unsheltered high-latitude anchorages shall not be used for storm sheltering during severe gales; well-sheltered designated storm anchorages shall be selected instead.
• Berthing control: Vessels alongside shall coordinate storm response plans with the terminal and agents in advance. Increase mooring lines as wind strengthens and equalise line tension. High-latitude ports often experience storm surges and rapid water level fluctuations in winter; monitor tide levels closely and adjust mooring lengths accordingly. Suspend cargo operations decisively when sea conditions deteriorate, and depart for shelter if necessary.

4. Post-storm Inspection

After weather abates, the chief officer shall lead a thorough inspection of hull structures, deck equipment, cargo hold watertightness, pipelines and valves. Confirm no damage or water ingress, and record and rectify defects promptly.

Equipment Freeze Protection: System Maintenance in Low-temperature and Icy Environments

Low temperatures may burst pipelines, raise hydraulic oil viscosity and cause starting failures. Extreme temperatures can drop below -20°C in high-latitude areas of the North Atlantic and North Pacific, compounded by sea ice abrasion, imposing stricter freeze protection requirements than coastal China. Protection measures shall cover critical systems throughout the vessel.

1. Pipeline and Tank Freeze Prevention

• Ballast and fresh water systems: Leave sufficient expansion space in ballast tanks and fresh water tanks to prevent rupture from freezing. Vessels operating along China’s coast shall drain exposed fire lines and deck water pipes or add antifreeze. High-latitude vessels shall inject antifreeze into ballast water or circulate ballast water regularly to prevent ice formation on tank boundaries, with increased inspection frequency under extreme cold. Sea chests and suction inlets shall be fitted with ice screens and checked routinely for blockage by frazil ice.
• Engine room piping: Monitor fuel viscosity and ensure fuel heating systems function properly to prevent filter clogging. Maintain proper cooling water temperature; drain vulnerable sections after shutdown. Drain condensate frequently from compressed air systems to avoid icing. All exposed piping shall be insulated and trace heating kept operational.

2. Deck Machinery Freeze Protection

For hydraulic equipment including windlasses, mooring winches and steering gear, replace hydraulic oil and lubricants with low-pour-point grades before winter. For ice navigation in high latitudes, dedicated low-temperature hydraulic fluids are required. Preheat and test run exposed machinery before startup; protective covers shall be fitted where applicable. Check outdoor fire-fighting and life-saving appliances including fixed dry powder systems, fire hose boxes and extinguishers for pressure and sealing integrity to avoid impaired agent performance or valve blockage. Lifeboat engines shall be test-run daily with thermal insulation fitted; release mechanisms shall be inspected regularly to prevent seizure by ice.

3. Navigation and Communication Equipment

Binnacle repeaters, radar scanners, navigation lights and signal lights on bridge wings shall be inspected and cleared of snow and ice routinely. During high-latitude voyages, scanner de-icing checks are required to prevent degraded radar returns and signal loss. Keep ferromagnetic ice-prone objects away from the magnetic compass to preserve heading accuracy. Verify echo sounder performance before ice transit to avoid distorted readings from floating ice.

Crew Cold Protection: Personal Safety in Low-temperature Extreme Environments

Cold temperatures, slippery deck surfaces and high winds greatly raise risks of frostbite, slips and falls, especially in frigid high-latitude waters. Work permits and PPE management shall be enforced strictly.

1. Work Permit and On-site Control

Outdoor deck work shall be avoided as far as possible during gales and severe cold. If work is essential, approval and a work permit must be issued by the master. Two-person watch is mandatory. Workers shall fasten collars, cuffs and trouser hems, wear anti-slip footwear and cold-weather suits, and keep safety harnesses secured for working aloft. In high-latitude North Atlantic and North Pacific waters, wind chill is extreme. A single continuous outdoor task shall not exceed 30 minutes with rotating shifts to prevent severe frostbite.

2. Workplace Management

Clear ice, snow and frost from decks, gangways and platforms promptly and lay anti-slip mats. Handrails at passageways and ladders shall be maintained, with warning signs at high-risk locations. Deck ice clearance is critical during ice operations to prevent loss of footing.

3. Health and Watchkeeping Support

Adequate heating and ventilation shall be maintained in crew accommodation. First-aid supplies for frostbite and colds together with rewarming equipment shall be available. Watch schedules shall be arranged rationally to avoid prolonged cold exposure and fatigue. All crew shall master first-aid procedures for frostbite and administer treatment immediately upon symptoms.

Special Controls for High-latitude Winter Navigation

Widespread sea ice occurs in the northern North Atlantic, Bering Sea, Sea of Okhotsk and similar waters in winter. These are restricted special areas requiring more stringent ice navigation rules on top of standard gale and freeze protection measures.

1. Watchkeeping Escalation

During ice navigation and transit through high-latitude storm zones, enhanced watchkeeping standards apply: the master shall remain on the bridge at all times, extra lookouts posted, main engine on standby and both steering gears operational under hand steering. Additional forepeak lookouts shall be arranged in congested ice zones to report ice conditions and obstructions continuously.

2. Under-keel Clearance and Manoeuvring Control

Account for ice resistance, draft changes and subsea ice features when calculating under-keel clearance, complying with company policies to avoid shoals and submerged ice hazards. Reduce speed through pack ice to prevent hull and propeller impact damage. Avoid large rudder angles which may aggravate heel and squeezing forces from ice floes.

3. Visibility and Ice Monitoring

Snow squalls and sea fog frequently reduce visibility in the two oceans. Comply fully with restricted visibility procedures: sound fog signals, exhibit navigation lights, monitor surrounding traffic and ice via radar, and heave-to if necessary. Track ice distribution continuously using ice charts, satellite imagery and visual observations. Avoid entering heavy ice concentrations; divert or heave-to until ice conditions ease if dense pack ice is encountered.

Administrative Requirements and Emergency Response

• Responsibility implementation: Establish an onboard winter safety team. Department heads shall complete inspections and corrective actions as assigned, with full records retained. Ocean-going vessels shall develop bespoke winter safety plans tailored to the route and submit them to the ship management office for filing.
• Emergency preparedness: Develop dedicated winter contingency plans covering dragging anchor, pipeline bursting, crew frostbite, machinery failure and entrapment in ice. Organise deck and engine room emergency response teams and conduct regular drills to ensure rapid reaction.
• Reporting and record-keeping: Log meteorological observations, equipment checks and emergency actions fully in the deck logbook and engine room logbook. Ocean-going vessels shall report position, sea state and response measures to the shore management team at specified intervals when encountering extreme weather, ice events or machinery faults, and request shore technical support if needed. Report incidents or accidents immediately to the company and maritime authorities, while preserving scene evidence.