Fire behaviour
Governing: STCW Code Table A-VI/3, competence 'control fire-fighting operations'. Builds on: Fire Prevention and Fire Fighting (FPFF).
FPFF taught you to put out a fire. AFF assumes you will be the one deciding how, when and with whom. That starts with reading the fire correctly.
The tetrahedron, briefly
Fire needs four things: fuel, heat, oxygen and a self-sustaining chain reaction. Every tactic you will order attacks one of them.
| Element | How you attack it | Typical means |
|---|---|---|
| Heat | Cooling | Water jet or spray, boundary cooling |
| Oxygen | Smothering | Closing the space, CO2, foam blanket |
| Fuel | Starvation | Fuel shut-offs, removing combustibles |
| Chain reaction | Inhibition | Dry powder, some clean agents |
How heat moves on a yacht
- Conduction. Steel and aluminium carry heat into the next compartment. A fire in the galley can ignite the veneer panels of the crew mess through an intact bulkhead.
- Convection. Hot smoke and gases rise through stairwells, lift trunks and service ducts. The guest atrium is a chimney.
- Radiation. Heat from flame and hot smoke preheats everything in the space until it all ignites together.
Process hazards in the STCW table
Table A-VI/3 names hazards an officer in charge must recognise:
- Dry distillation. Heat drives flammable vapours out of linings, foam and furnishings before any flame reaches them. The gas collects behind panels and in deckheads, then ignites violently.
- Chemical reactions. Cleaning products, pool chemicals and oxidisers stored together can generate heat or toxic gas.
- Boiler uptake fires. Rare on motor yachts, but the equivalent risk lives in exhaust trunks and funnel casings where soot and oil residue accumulate.
- Dangerous goods and stored materials. Paints, thinners and resins in the bosun's store; fuel for tenders and toys.
The stages of a compartment fire
| Stage | What you see | Command implication |
|---|---|---|
| Incipient | Smoke, small flame | Extinguisher attack, isolate power |
| Growth | Flame spreading, rising heat layer | Close the space, boundary cool, muster teams |
| Flashover | Everything ignites at once | No entry; contain from outside |
| Fully developed | Ventilation-controlled | Plan fixed system or indirect attack |
| Decay | Fuel exhausted | Watch for re-ignition |
WARNING - Flashover and backdraught Flashover follows heat build-up; the warning signs are rolling flame in the smoke layer and heat forcing crew low. Backdraught follows air admission to an oxygen-starved fire: pulsing smoke at door gaps, blackened glass, a warm door. Never open a door you have not assessed.
Yacht fuel loads
A superyacht is fitted out like a hotel and built like a ship. Expect:
- Joinery and veneers in guest areas, glued to combustible substrates.
- Soft furnishings throughout.
- Composite or aluminium superstructure on many builds, which loses strength in heat well before steel does.
- Lithium-ion batteries in e-foils, seabobs, drones and tender stores. They can run away thermally, vent toxic gas and re-ignite after apparent extinction.
TIP - Know your boundaries Walk the fire control plan with the chief engineer and mark every space where conduction or ducting would carry fire from a high-risk space (galley, laundry, engine room, toy store) into guest or crew accommodation.