A marine boiler generates steam by heating water, serving multiple essential functions aboard a ship beyond simply providing heat.
Main Types
- Oil-fired (auxiliary) boiler — burns fuel oil directly to generate steam, used particularly when the main engine isn’t running (in port) or when demand exceeds what waste heat recovery can supply
- Exhaust gas economizer — recovers waste heat from the main engine’s exhaust gas to generate steam without additional fuel consumption, a fuel-efficient approach used whenever the main engine is running
What Boiler Steam Is Used For
- Fuel oil heating — heavy fuel oil must be heated to reduce viscosity for proper pumping and combustion
- Cargo heating — particularly relevant on tankers carrying viscous cargo requiring temperature maintenance
- Accommodation heating and hot water systems
- Tank cleaning — hot water/steam assists in cleaning cargo and other tanks
Boiler Safety
Boilers operate under pressure and involve significant heat, making them a genuine safety-critical system — proper water level control, pressure relief valves, and combustion safety systems are essential, with boiler-related incidents historically among the more serious engine room casualty categories.
Boiler Water Treatment
Boiler feedwater requires chemical treatment to prevent scale formation and corrosion inside the boiler — a routine but essential engine room maintenance task with real consequences for boiler longevity if neglected.
Exam Relevance
Boiler types, operation, and safety systems are core engine knowledge topics in MEO competency exams.