Question 1

During cargo transfer at a terminal, a hose connection fails and approximately 200 litres of crude oil spills onto the manifold area. Some oil enters the sea. What are your immediate actions?

Accepted Answer

OIL SPILL RESPONSE — CM: (1) STOP THE SOURCE: "STOP CARGO PUMPS — ESD ACTIVATE." Immediately stop cargo transfer and close manifold valves. Use the Emergency Shutdown procedure agreed with terminal before operations. This is the most critical first action; (2) ALERT TERMINAL: inform the terminal control room and request their emergency response team. The terminal has oil spill response equipment; (3) CONTAIN ON DECK: close manifold area drains, deploy SOPEP kit absorbent materials on deck to contain oil not yet in the sea; (4) GENERAL ALARM / MASTER: notify the master immediately. This is a MARPOL reportable incident; (5) OIL RECORD BOOK: the spill MUST be entered in the Oil Record Book Part II with: time, position, estimated quantity, cause, and action taken; (6) SOPEP (Shipboard Oil Pollution Emergency Plan): activate the vessel's SOPEP — MARPOL Annex I Reg 37 requires all vessels over 150 GT to carry a SOPEP. The plan identifies: responsible persons; notification contacts (flag state, coastal state, MRCC, port authority); response procedures; SOPEP equipment inventory; (7) PORT AUTHORITY NOTIFICATION: OIL SPILL INTO PORT WATERS — must be reported immediately to the port authority/coastguard. Under MARPOL and national regulations this is a mandatory report; (8) P&I CLUB: notify immediately — the P&I Club pollution response team can assist; (9) EVIDENCE: photograph the spill and the failed hose connection. Do not tamper with the failed equipment until it has been photographed and inspected. MARPOL reporting threshold: MARPOL Annex I has NO de minimis threshold for reporting oil spills into port waters or territorial seas. Any oil spill that results in oil reaching the sea water surface in port must be reported to the port authority. The MARPOL Annex I Regulation 14 "harmful substances" definition includes crude oil at any quantity that creates a sheen on water. Zero-tolerance in port: many jurisdictions (US COFR, EU, UK) have zero-tolerance for oil spills in harbour limits. The fine structure in the US under OPA 90 can reach millions of dollars regardless of quantity. The 500-litre threshold (option B) does not exist. Immediate CM action (option C): the CM does not wait for the master before stopping cargo transfer. Stopping the source of a spill is an emergency action within the CM's authority and is the most critical action. If the CM delayed to await master authority while oil continued to flow overboard — that delay would constitute a professional failure and would aggravate the pollution incident. SOPEP: the Shipboard Oil Pollution Emergency Plan is MARPOL-mandated. It must be submitted to and approved by the flag state. It contains a pre-completed notification card with all required phone numbers. The CM should be familiar with the SOPEP for their vessel — oral examiners may ask for specific SOPEP notification requirements. Oil recovered from water (option D): even if oil is successfully recovered, the incident must still be reported. The obligation to report attaches at the moment of spill, not after the outcome.

Question 2

As Chief Mate on a product tanker, explain the purpose and operation of the inert gas system before cargo discharge.

Accepted Answer

INERT GAS SYSTEM (IGS) — CM KNOWLEDGE: PURPOSE: The IGS prevents flammable hydrocarbon vapours from reaching an explosive concentration in cargo tanks. A hydrocarbon-air mixture is flammable between approximately 1-10% hydrocarbon concentration (LEL to UEL). The IGS keeps O2 concentration below 8% (SOLAS requirement: below 8% O2 by volume) — at this level, the vapour cannot ignite regardless of hydrocarbon concentration. SYSTEM COMPONENTS: (1) SOURCE: combustion gas from the ship's boiler or dedicated inert gas generator (IG generator using gas turbine or diesel exhaust). Typical O2 content of flue gas: 2-5%; (2) SCRUBBER: removes corrosive components (SO2, H2S, soot) from the flue gas before it enters tanks. Water is the scrubbing medium; (3) BLOWER (FANS): propel the scrubbed gas into the distribution main; (4) DECK WATER SEAL: the critical safety device between the blower and cargo tanks. Prevents backflow of hydrocarbon gas to the machinery space if fans fail. Always maintained wet; (5) P/V BREAKER: secondary protection against overpressure/underpressure in tanks; (6) O2 ANALYSER: continuous monitoring of O2 content in the IG supply and individual tanks. PRE-DISCHARGE PROCEDURE: (1) Check O2 content of all cargo tanks — must be below 8% by volume; (2) Ensure IG pressure positive in tanks before beginning discharge (tank pressure > atmospheric); (3) Start IG supply to replace vapour volume as cargo is discharged; (4) Monitor O2 levels throughout discharge; (5) Never open tank in oxygen-enriched atmosphere without gas-free certificate. IGS SOLAS requirement: SOLAS II-2/4.5.5 — inert gas systems are required on crude oil tankers over 20,000 DWT and product carriers over 40,000 DWT. Failure to maintain the IGS is a detainable deficiency under PSC. The flammability triangle: three elements required for fire — fuel (hydrocarbon vapour), oxygen (above 10-11%), and ignition source. The IGS removes oxygen below 8%, eliminating one corner of the triangle. O2 below 8%: at this level, even if there is 100% hydrocarbon vapour in the space, the mixture cannot ignite. This is the safety principle of the IGS. The deck water seal: critical safety device. If the IG fans fail, backflow of hydrocarbon vapour toward the boiler (ignition source) must be prevented. The water seal provides a physical barrier. If the seal runs dry — the IGS is compromised. The CM must ensure the water level is maintained. CO2 confusion (option C): the IG system uses boiler flue gas (N2 + CO2 + water vapour — low O2), NOT pure CO2. The CO2 fixed fire system is separate and is used for firefighting in cargo holds on other vessel types. IGS during discharge (option B): during discharge, as liquid cargo leaves the tank, the vapour space increases. If the tank is not kept under positive IG pressure, air could be drawn in through vapour venting points and create a flammable mixture. IGS must run continuously throughout discharge.

Question 3

Your crude oil tanker is 4 hours from the terminal. As Chief Mate, what pre-arrival preparations do you coordinate?

Accepted Answer

PRE-ARRIVAL CRUDE TANKER — CM PREPARATIONS: (1) SHIP-SHORE COMMUNICATIONS: make contact with the terminal. Confirm: berth availability; cargo order; hose/arm connection details; cargo plan and loading/discharge sequence; free flow/simultaneous operations restrictions; emergency shutdown procedures; (2) CARGO PLAN: prepare/review the loading or discharge plan — cargo sequence, tank allocation, ullages, API gravity, temperatures, transfer rates; (3) STABILITY: calculate stability at all stages of the cargo operation. Ensure GM remains positive throughout. Identify the critical condition (minimum GM stage); (4) TANK CONDITION: check all cargo tank O2 levels — below 8% required. Note temperature and pressure of cargo and tank atmosphere; (5) MANIFOLD PREPARATION: inspect manifolds — blank flanges removed, drip trays clear, manifold valves operational; manifold pressure rating confirmed compatible with terminal pumps; (6) MOORING PLAN: confirm berth orientation; prepare appropriate mooring lines; (7) PUMPROOM INSPECTION: access pumproom — check bilge level; inspect pump seals; ensure cargo pumps ready for operation; (8) CARGO HEATING: if heated cargo — ensure steam coils operational and steam supply available; (9) DECK EQUIPMENT: cargo deck valves operated (any seized valves to chief engineer); hose handling equipment ready; (10) ISGOTT SHIP-SHORE SAFETY CHECKLIST: complete the ISGOTT pre-arrival section of the Ship-Shore Safety Checklist (Part A — ship's responsibilities) before the terminal vessel inspector arrives; (11) HOT WORK SUSPENDED: ensure all hot work is completed and stopped before entering port limits; (12) EMERGENCY SHUTDOWN: brief the duty officer on the ESD procedure and agree a shore contact name. ISGOTT (International Safety Guide for Oil Tankers and Terminals): the industry reference document for tanker terminal operations. The Ship-Shore Safety Checklist in ISGOTT: completed jointly by the vessel and the terminal before cargo operations begin. Part A covers vessel systems; Part B covers terminal systems. Both must be completed and signed. CM role in pumproom (option D): the pumproom is a critical space on a tanker — it contains all cargo pumps, stripping pumps, ballast pumps, valves, and pipework. Pumproom entry has caused numerous casualties (enclosed space, H2S accumulation, flooding). The CM has direct responsibility for cargo operations, which includes ensuring the pumproom equipment is operational. Chief engineer: responsible for maintenance of the cargo pumps as machinery, but the CM is responsible for the cargo operation, which requires those pumps. The Manifold safety: manifold flanges must be compatible between ship and shore hose/arm flanges. The pressure rating of the shore supply must not exceed the ship's manifold rated pressure. MARPOL Annex I: on a crude oil tanker, any oil discharge or spill must be reported. The pre-arrival preparation includes ensuring all drain plugs are in drip trays and that the manifold area is ready to contain any hose drips. Cargo heating: for high-viscosity crudes, the cargo may need to be maintained at 40-60°C or above throughout the voyage. The CM must check that the heating system is functional before arrival at the discharge port.