Marine Galley Ventilation Systems: Standards, Calculations and Installation
A ship’s galley — the cooking area of a marine vessel — is a confined space producing intense heat, humidity, and grease vapors. Without adequate ventilation, these conditions directly compromise crew health, fire safety, and the lifespan of galley equipment.
A marine galley ventilation system is far more than a hood and an exhaust fan. Correct airflow calculation, SOLAS fire safety requirements, classification society standards, and compatibility with the vessel’s electrical system must all be addressed together. This guide covers each of these topics step by step.
1. Why Is Ventilation Critical in a Marine Galley?
In a shore-based restaurant kitchen, a window or door can be opened if ventilation is inadequate. On a ship, this is impossible. The galley is a closed steel box; heat, humidity, grease vapor, and combustion gases can only exit through the designed exhaust ducts.
Consequences of inadequate ventilation:
- Fire risk: Grease accumulating in hood filters creates an ignition source — SOLAS includes specific regulations addressing this.
- Crew health: Build-up of CO, NO₂, and grease vapor causes long-term respiratory problems.
- Equipment lifespan: Condensed moisture and grease cause premature failure in galley equipment and electrical systems.
- Class inspection: An inadequate ventilation system can result in a non-conformance finding during class survey.
2. Airflow Calculation: CFM and m³/h Methods
Ventilation capacity is expressed in two units: CFM (cubic feet per minute — American/maritime standard) and m³/h (cubic metres per hour — European standard). Conversion: 1 CFM ≈ 1.699 m³/h.
Calculation Methods
| Method | Formula / Rule | When to Use |
|---|---|---|
| Volume-based | Galley volume × 30–60 air changes/hour | Preliminary calculation, small galleys |
| Heat load-based | Total heat load (kW) × 0.8 m³/h/kW factor | Equipment-intensive projects |
| Hood capture velocity | Hood opening area (m²) × 0.3–0.5 m/s capture velocity | Hood sizing |
Practical rule: Plan a minimum of 60–80 m³/h exhaust capacity per kW of heat load. For a galley with a total heat load of 30 kW, a minimum exhaust capacity of 1,800–2,400 m³/h is required.
Reference Values by Vessel Type
| Vessel Type | Crew | Estimated Exhaust Capacity | Air Changes |
|---|---|---|---|
| Small cargo vessel | 10–15 | 1,500–2,500 m³/h | 30–40/hour |
| Mid-size cargo/container | 20–30 | 3,000–5,000 m³/h | 40–50/hour |
| Offshore support vessel | 50+ | 6,000–10,000 m³/h | 50–60/hour |
| Ferry / passenger vessel | Variable | Project-specific | 60+/hour |
| Yacht / superyacht | 5–20 | 800–2,000 m³/h | 25–35/hour |
3. SOLAS and Classification Society Standards
Marine galley ventilation systems must be designed to comply with SOLAS II-2 (fire protection) and the galley ventilation rules of classification societies.
- Hoods above cooking equipment must be made of fire-resistant material or equipped with a fire suppression system.
- Exhaust ducts must be fitted with fire dampers at compartment boundaries.
- Hood filters must be easily removable and cleanable to prevent grease accumulation.
- Automatic fire suppression systems (Ansul or equivalent) are mandatory on large commercial vessels.
4. Hood Selection and Technical Criteria
Hood Types
| Type | Application | Advantage |
|---|---|---|
| Wall-mounted | Cooking lines against a wall | Compact — ideal for confined galleys |
| Island type (ceiling-hung) | Central cooking islands | Capture from all sides — large galleys |
| Recessed | Yacht and superyacht projects | Aesthetic — no visible ductwork |
| Low-clearance | Vehicle decks and boat projects | Suits low deckhead clearance |
Filter Systems
- Baffle filter: Most common type. Grease particles impact the baffle surface and drain away. Removable and dishwasher-safe. SOLAS compliant.
- Cassette filter: Additional protection for finer grease particles. Added behind the baffle filter.
- Activated carbon filter: Additional odour removal layer. Preferred in yacht projects for interior comfort.
5. Exhaust Fan and Duct System
Key considerations when selecting a marine exhaust fan:
- Voltage / Frequency: 440V/60Hz or 380V/50Hz — must match the vessel’s electrical system.
- Grease resistance: Fan blades and housing must be made of grease-vapour-resistant materials.
- Static pressure capacity: Must overcome the static pressure losses calculated from duct length and number of bends.
- Speed control: Variable speed via frequency inverter — automatic adjustment to cooking intensity.
- Vibration isolation: Marine fans must be mounted with vibration-damping connections.
6. Make-Up Air: Fresh Air Balance
The most common mistake: designing the exhaust system, but forgetting the fresh air supply. If sufficient make-up air is not provided to replace the volume extracted by the exhaust system, the system operates under negative pressure — doors won’t open, exhaust performance drops, and flames can flicker.
Golden rule: Supply make-up air equal to 80–90% of exhaust capacity. The remaining 10–20% keeps the galley at a slight negative pressure, preventing galley air from migrating to adjacent spaces.
7. Installation Rules
- Distance from the hood’s lower edge to the cooking surface: 650–900 mm (varies by type and heat load).
- Hood width must extend at least 150 mm beyond the cooking equipment on each side.
- Exhaust duct should be as short and straight as possible.
- Fire dampers must be installed at all compartment boundaries.
- Fan should be positioned at the highest point to prevent grease accumulation.
- Duct system must be fitted with a cleanout access panel every 3 metres.
- Installation must receive naval architect approval and class society survey.
8. Periodic Maintenance Schedule
| Maintenance Item | Frequency | Notes |
|---|---|---|
| Baffle filter cleaning | Weekly (heavy use) | Dishwasher compatible |
| Hood interior cleaning | Monthly | Especially grease drain channel |
| Exhaust duct interior cleaning | Every 6 months | Via cleanout access panels |
| Fan inspection and lubrication | Every 3 months | Including vibration and noise check |
| Fire damper test | Every 6 months | May be required by class society |
| Make-up air balance check | Annually | With measuring instrument |
Frequently Asked Questions
Can a standard land-based hood be used on a ship?
No. Land-based hoods are not designed to withstand a vessel’s rolling and vibration conditions, and do not meet SOLAS requirements for duct thickness and fire dampers.
How large should the hood be?
The hood must extend at least 150 mm beyond the cooking equipment on each side. Height is set so the gap between the cooking surface and the hood’s lower edge is 650–900 mm. Exact dimensions are determined by heat load calculation.
Why is make-up air important?
Without enough fresh air to replace the exhaust volume, excessive negative pressure builds in the galley. Exhaust performance drops, doors won’t open, and flames can flicker. Plan make-up air at 80–90% of exhaust capacity.
How often should grease filters be cleaned?
In heavily used commercial ship galleys, baffle filters should be cleaned at least once a week. Uncleaned filters create a serious fire risk from grease accumulation.
What is needed to order a custom-size hood?
A technical drawing or on-site measurement of the galley, a list of cooking equipment with heat outputs, the vessel’s electrical system (440V/60Hz or 380V/50Hz), and the project class society are sufficient. If no drawing exists, we perform an on-site measurement.