Question 1

Your vessel is routed through the northern Baltic Sea in February. As Chief Mate, what ice navigation preparations do you make for a vessel with no polar class rating?

Accepted Answer

NORTHERN BALTIC WINTER PREPARATION — NON-POLAR CLASS VESSEL: The northern Baltic (Gulf of Finland, Gulf of Bothnia) freezes regularly in winter. An ordinary commercial vessel (no ice class) requires careful preparation: INFORMATION GATHERING: (1) ICE CHARTS: Finnish Meteorological Institute and Swedish Meteorological Institute provide daily/weekly ice charts for the Baltic. Current ice extent, ice thickness, fast ice limits, polynya locations; (2) ICEBREAKER REQUIREMENTS: Finnish and Swedish maritime authorities impose WINTER NAVIGATION RESTRICTIONS. These specify the minimum vessel ICE CLASS required to proceed to specific Finnish and Swedish ports without icebreaker escort. A vessel with no ice class may be prohibited from proceeding without icebreaker assistance; (3) ICEBREAKER CONTACT: contact the Finnish Icebreaker Pool (Arctia Icebreaking) or Swedish Maritime Administration for icebreaker availability and convoy scheduling; VESSEL PREPARATION: (4) ANCHOR WINDLASS: test anchor windlass in cold — hydraulic systems can thicken. Grease with low-viscosity lubricant; (5) HEATING: trace heating on exposed pipes, deck water mains, fire main. Prevent freezing of safety systems; (6) STABILITY: ice accretion on superstructure adds topweight. Assess maximum expected ice accretion and impact on GM; (7) ENGINE AVAILABILITY: ice navigation requires engine on immediate standby — no planned maintenance windows; (8) CREW BRIEFING: ice navigation — reduced speed, no sudden manoeuvres, follow the icebreaker's channel, do not attempt shortcuts through ice; (9) DECK OFFICER LOOKOUT: additional lookout forward for ice concentration changes. Finnish-Swedish Winter Navigation System: Finland and Sweden have operated a joint winter navigation system since 1971. The system classifies vessels into Ice Classes (1A Super, 1A, 1B, 1C, and II) based on hull strength and propulsion power. In winter, each port has a minimum Ice Class requirement that changes with ice conditions. A vessel with no ice class may be: (a) refused entry to the port without icebreaker assistance; (b) required to wait at an anchorage for an icebreaker convoy. Masters and chief mates navigating to Baltic ports in winter must check the current winter navigation restriction notices from Finnish and Swedish maritime authorities before departure. Ice accretion stability: in cold temperatures with spray and freezing conditions, ice accumulates on exposed structures. The IS Code (MSC.267(85)) includes guidance on ice accretion allowances for stability calculations. A vessel in icing conditions can accumulate tonnes of topweight, reducing GM. The chief mate must assess whether the vessel's stability margins are adequate for icing conditions. Standard commercial hull vs ice: a commercial vessel with no ice class has hull plating and framing designed for water pressure — not for ice contact. Hull contact with pack ice or ridge ice at speed can cause hull damage. "Add speed to break through" (option B) is extremely dangerous — it increases impact energy with ice, increasing hull damage probability. In ice, reduced speed is always the correct approach for non-ice-classed vessels. Polar Code vs Baltic ice class: the Polar Code applies to Arctic and Antarctic waters. The Baltic has its own Finnish/Swedish ice class system, which predates the Polar Code and remains the relevant regulatory framework for Baltic winter operations.

Question 2

As Chief Mate on a chemical tanker, you are planning to load benzene (UN 1114, Class 3, PG I) after carrying methanol. What segregation, tank preparation, and safety measures apply?

Accepted Answer

BENZENE LOADING AFTER METHANOL — CHIEF MATE's PLANNING: CARGO COMPATIBILITY CHECK: (1) Are methanol and benzene compatible for sequence loading? Methanol (Class 3/6.1) and benzene (Class 3) are both flammable — BUT they are not compatible in the sense that residual methanol in a benzene cargo = CONTAMINATION. Check the IBC Code compatibility matrix and the charterer's cargo compatibility requirements; (2) TANK WASHING: tanks previously carrying methanol must be thoroughly washed before benzene loading. Methanol is water-soluble and miscible — water washing followed by recirculation is appropriate. Complete drying is required as water in benzene cargo = haze/contamination; (3) BENZENE PROPERTIES (UN 1114): (a) Class 3, Packing Group I (very high flammability); (b) Boiling point 80°C, flashpoint -11°C (extremely flammable); (c) TOXIC: a human carcinogen (Group 1 IARC). Vapour exposure risk — PPE: SCBA and full chemical protection suit for all operations; (d) Vapour density 2.7 (heavier than air — accumulates in low areas); (4) MARPOL ANNEX II: benzene is Annex II Category X substance (most hazardous). Pre-washing before any discharge — MANDATORY; (5) IBC CODE SPECIAL REQUIREMENTS: benzene requires closed loading, vapour return line (vapour recovery or destruction), enclosed gauging (no open ullaging), and restricted access during loading; (6) SAFETY ZONE: 3-metre exclusion zone around manifold during loading operations. No ignition sources within 30m. IGS may not be required (benzene is non-reactive to inert gas atmospheres) but nitrogen blanket may be required; (7) EMERGENCY: EmS F-E (flammable liquids fire) and S-E (spillage). Benzene as a carcinogen: benzene is classified as a Group 1 carcinogen by IARC (International Agency for Research on Cancer). The IMDG Code and IBC Code impose additional health protection requirements beyond standard Class 3 liquid handling. Exposure limits: the UK COSHH regulations specify a Workplace Exposure Limit (WEL) for benzene of 1 ppm (8-hour TWA). This is extremely low — the vapour pressure of benzene at ambient temperature means significant benzene vapour can be present at open ullage points, manifold areas, and any open sampling. ALL operations involving benzene cargo must use SCBA and appropriate chemical protection. IBC Code Chapter 15 special requirements: Chapter 15 of the IBC Code specifies additional cargo-specific requirements for each chemical. For benzene — these include: (a) vapour emission control; (b) closed operations; (c) emergency shutdown system; (d) health monitoring for crew. MARPOL Annex II Category X: benzene is among the most strictly regulated liquid cargoes under MARPOL Annex II. Discharge into the sea of any benzene-contaminated washwater is absolutely prohibited unless processed through a compliant retention/disposal system. Pre-wash is mandatory before ANY discharge of residues in any sea area. Cross-contamination (option B): loading benzene into a tank with methanol residue creates a contaminated benzene cargo. Methanol is infinitely miscible with benzene — even small traces will reduce benzene purity below specification. Additionally, water from tank washing that is not completely dried creates a benzene/water haze that similarly renders the cargo off-specification.

Question 3

In port, a cargo hold is opened and a strong smell of chlorine is detected. The manifest shows UN 1017 (Chlorine, Class 2.3 Toxic Gas) in the lower hold. Crew members are near the hold. As Chief Mate, what do you do?

Accepted Answer

CHLORINE GAS RELEASE — EMERGENCY RESPONSE: UN 1017, CHLORINE, CLASS 2.3: (a) Extremely toxic gas — IDLH (Immediately Dangerous to Life and Health) 10 ppm; (b) Heavier than air (vapour density 2.5) — accumulates at low levels in holds; (c) Bleach-like odour detectable at 0.5 ppm — if crew can smell it, concentrations may already be dangerous. IMMEDIATE ACTIONS — FIRST 60 SECONDS: (1) SHOUT AND CLEAR: warn all crew in the vicinity to MOVE AWAY UPWIND. Do not send crew into the hold without SCBA; (2) WIND AWARENESS: position crew UPWIND of the hold opening. Chlorine disperses downwind; (3) NO IGNITION SOURCES: chlorine in combination with hydrogen (from bilge gas) could explode — no smoking, no naked flames. However, chlorine itself is not flammable; (4) CALL THE MASTER: immediate notification; (5) SOUND GENERAL ALARM: if the release is significant or risk of spread to accommodation; (6) CLOSE THE HOLD: if it can be done safely from outside without entering — secure the hold to contain the release; (7) EMERGENCY SERVICES: contact port authority and emergency services (shore fire brigade with HazMat team); (8) IMDG EmS: EmS code for UN 1017 is F-C (non-flammable gas fire) and S-U (toxic gas spillage). S-U: keep people away from damaged area. Contact 24-hour emergency advice centre; (9) EMERGENCY CONTACT: the DG manifest must show a 24/7 emergency contact. Call them immediately; (10) DO NOT VENTILATE BY BLOWING AIR INTO HOLD: this could disperse chlorine gas to adjacent areas. Chlorine toxicology: chlorine is one of the most dangerous gases that can be encountered on a cargo vessel. WWI chlorine gas attacks used concentrations above 1,000 ppm — but even at 30 ppm, severe chest pain, vomiting and pulmonary oedema occur. At 430 ppm — death within 30 minutes. Critically: chlorine is HEAVIER than air — it accumulates at the lowest point (bottom of the hold). Crew near the open hatch may not immediately appreciate the concentration at lower levels in the hold. IMDG EmS S-U: the Spillage Schedule for toxic gases (S-U) specifies: "ELIMINATE all ignition sources. STOP leakage only if safe to do so. Move people from danger area upwind. Advise competent authority of potential hazard. Contact chemical experts." "Rag over the face" approach (option C): chlorine at dangerous concentrations is immediately incapacitating. A crew member who enters a hold with chlorine vapour above IDLH using a rag as protection will quickly become incapacitated. This would turn a dangerous goods incident into a rescue situation requiring entry into a toxic atmosphere — putting additional lives at risk. The USCG and MAIB have investigated several cargo incidents where rescue attempts without SCBA resulted in rescuers also becoming casualties. Ventilation with fans (option B): ventilating by blowing air INTO the hold could spread chlorine gas to adjacent spaces, including engine room intakes and accommodation. The correct approach is to CLOSE the hold and control the release, allowing emergency services with HazMat equipment to handle decontamination. Detection threshold vs danger threshold: the detection odour threshold for chlorine is 0.5 ppm. This is BELOW occupational exposure limits (1 ppm ceiling under COSHH). Detection does not mean safe — it means dangerous concentrations may be nearby.