Question 1

At 0400 the fire detection system alarms for No.2 cargo hold. The hold contains a general cargo consignment. You are OOW. Describe your immediate actions.

Accepted Answer

Sound general alarm; call master; post personnel at the hold access to prevent unauthorised entry; check the nature of the alarm (smoke, heat, or CO detector); do NOT open the hatch — opening the hatch introduces oxygen and can cause backdraft or flashover. Check adjacent hold temperatures and spaces. Close ventilation to the hold. Inform chief officer and chief engineer. Muster emergency team in full PPE with BA sets ready. Obtain cargo manifest to identify cargo type and any dangerous goods. Consider applying fixed CO2 or inert gas system if fitted for that space. Prepare to report to MRCC with situation details. Cargo hold fires are among the most dangerous shipboard fires because: (1) the cargo type may be unknown or mislabelled — IMDG dangerous goods create specific hazards; (2) opening the hatch introduces oxygen, potentially causing rapid fire growth or backdraft explosion; (3) the space is confined and inaccessible; (4) fire suppression systems (CO2 or inert gas) are the primary defence. The cargo manifest and dangerous goods declaration must be checked immediately — a hold containing self-heating materials (e.g. wet fishmeal, charcoal, coal) has different hazard characteristics from a general cargo hold. SOLAS II-2/20 requires cargo ships to carry detailed information on dangerous goods to assist in firefighting planning. The OOW's primary role in the first minutes is: sound alarm, inform master, isolate the space (close ventilation, do not open hatch), and get the emergency team mustered and equipped. The false alarm possibility is real — but the correct procedure is to treat every alarm as real until proved otherwise.

Question 2

Your examiner asks: "Describe the fire triangle and the four internationally recognised classes of fire relevant to shipboard operations. Which extinguishing media are correct for each?"

Accepted Answer

The fire triangle requires three elements simultaneously: heat (ignition source), fuel (combustible material), and oxygen. Remove any one element and the fire goes out. Classes: Class A — solids (wood, rope, bedding) — water, foam, dry powder; Class B — flammable liquids (fuel oil, paint, solvents) — foam, CO2, dry powder; Class C — flammable gases (LPG, acetylene) — dry powder, shut off supply first; Class D — combustible metals (magnesium, titanium, sodium) — specialist dry powder only; Class F (electrical equipment) — CO2, dry powder — NEVER water. Note: electrical fires are sometimes classed separately rather than as a fire class. The fire triangle (heat, fuel, oxygen) underpins all firefighting strategy: cooling removes heat (water); smothering removes oxygen (CO2, foam blanket); starvation removes fuel (shut off supply, remove combustible material). Note the tetrahedron model adds a fourth element — the chain reaction — which halite extinguishing agents (Halon, now banned under MARPOL Annex VI except for existing systems) interrupt. Electrical fires (Class F in some classifications) must never be fought with water or foam — both conduct electricity. CO2 is the correct agent for switchboard and electrical equipment fires. Class D fires (metals) react violently with water — specialist dry powder (not standard ABC powder) is the only safe option. At OOW level, the examiner expects correct extinguishing media for each class and awareness that using the wrong agent can be dangerous.

Question 3

Your examiner asks: "What types of fire detectors are fitted on cargo ships under SOLAS Chapter II-2, and what are the conditions under which each type is most effective?"

Accepted Answer

Smoke detectors (ionisation or photoelectric): detect combustion particles — most effective for smouldering fires producing visible or invisible smoke before open flame. Heat detectors: either fixed-temperature (alarm at a set temperature, e.g. 57-96 degrees) or rate-of-rise (alarm when temperature rises faster than normal, e.g. 5 degrees per minute) — effective for fast-burning fires. Flame detectors: detect infrared or ultraviolet radiation from open flames — effective in machinery spaces with high background heat. Gas/carbon monoxide detectors: detect CO as an early indicator of smouldering fires. SOLAS II-2/7 requires automatic fire detection and alarm systems in crew accommodation, service spaces, control stations, and cargo spaces as appropriate. SOLAS II-2 Chapter 7 and the FSS Code Chapter 9 govern fire detection requirements. Key point for OOW orals: smoke detectors are the most sensitive for early detection of smouldering fires (which produce CO and aerosols before visible flames) — they are required in accommodation spaces. Heat detectors are more appropriate in galleys and machinery spaces where ambient temperatures and aerosols (cooking fumes, diesel exhaust) would cause false alarms from smoke detectors. Rate-of-rise detectors are faster-responding than fixed-temperature but can false-alarm in areas with rapid legitimate temperature changes (boiler rooms, hot work areas). Flame detectors are specifically required in unmanned machinery spaces. CO detectors as an early warning layer are increasingly specified in cargo hold monitoring systems. The FSS Code divides spaces into three categories: A (accommodation), B (service/machinery), and C (cargo) — each has specific detection requirements.