What are the types of main engine?

flowchart TD
    A[Main engine types] --> B[Two-stroke diesel]
    A --> C[Four-stroke diesel]
    B -->|cycle| D["1 revolution: compression, power"]
    B -->|gas exchange| E["ports + exhaust valve, forced scavenging"]
    C -->|cycle| F["2 revolutions: induction, compression, power, exhaust"]
    C -->|gas exchange| G["valve-operated, cleaner scavenging"]

• Core split: two-stroke and four-stroke diesel cycles
• Two-stroke: one revolution per cycle, ports + exhaust valve, forced scavenging, high power density, slow-speed direct drive
• Four-stroke: two revolutions per cycle, valve-operated gas exchange, cleaner scavenging, medium-speed
• As Second Engineer: know which type your ship has and why it was selected for the service profile