Ventilation control
Governing: STCW Code Table A-VI/3; REG Yacht Code Part A fire protection chapters. Builds on: L1.1, L1.2.
Table A-VI/3 lists ventilation control, including smoke extraction among the things an officer controlling a fire must know. On a yacht, with its stairwells, lift shafts, atria and extensive HVAC, ventilation decides whether you have a one-cabin fire or a one-deck fire.
What the Code gives you
The REG Yacht Code Part A requirements for vessels of 500 GT and over include:
- Power ventilation of accommodation, service spaces, control stations and machinery spaces can be stopped from an easily accessible position outside the space, not readily cut off by a fire in it.
- The stop for machinery space ventilation is entirely separate from the stops for other spaces.
- Atriums have a smoke extraction system, activated by smoke detection and capable of manual control, with fans able to exhaust the whole volume in 10 minutes or less.
- Stores for highly flammable products have separate ventilation, arranged to prevent vapour build-up at high and low levels.
Know where every stop, damper control and fan starter is. Fire control plans mark them; drills should use them.
Two jobs, often in conflict
| Aim | Action | Risk |
|---|---|---|
| Starve the fire | Stop fans, close dampers and doors | Smoke stays in escape routes |
| Clear escape routes | Extract or pressurise corridors and stairs | Feeds the fire if done at the wrong point |
The sequence resolves the conflict:
- Shut down ventilation to the fire zone and close dampers.
- Protect escape routes: close doors, keep stairway enclosures intact.
- Once the attack team is committed and boundaries are covered, vent deliberately: from a point downwind or downstream of the fire, with the exit path ready.
WARNING - Venting too early A fire that has been starved of air will re-intensify, or ignite explosively, the moment you open it up. Venting is a tactical decision for the on-scene commander, not a reflex.
Smoke behaviour aboard
- Smoke rises and spreads horizontally under deckheads, then banks down.
- It travels through cable penetrations, service ducts and lift shafts that may not be obvious on the plan.
- Glass atria and open-plan saloons allow very rapid spread across a deck.
- Toxic products from furnishings and batteries mean smoke is lethal well before it is hot.
Smoke extraction in practice
Use the atrium system as designed. For other spaces, portable smoke extraction fans, where carried, can clear a corridor once the fire is controlled. Place them to pull smoke away from the attack team and exits, not across them.
TIP - The HVAC engineer is part of your fire team On larger yachts the HVAC system is managed from a control screen, and dampers may be motorised. Make sure the officer on the bridge or in the ECR knows how to put the system into its fire mode, and test it at drills.
CAUTION - Machinery spaces Before any fixed gas release into a machinery space, ventilation must be stopped and openings closed, or the agent will be carried away. See L2.3.