Propulsion Plant and Machinery Operation
This domain tests whether you can run the main propulsion plant within its design limits, explain the systems that support it, and diagnose abnormal behaviour. Expect questions on starting and reversing, fuel injection and scavenging, turbocharging, load-up programmes and the relationship between power, speed and fuel consumption.
Core operational rules
- Starting air: SOLAS II-1/35 requires receiver capacity for 12 consecutive starts of a reversible engine (6 for a non-reversible one). Interlocks must prevent starting with the turning gear engaged, and prevent turning gear engagement while starting air is on the line.
- Load-up: follow the builder's programme. Loading a cold engine rapidly, or holding high load after long low-load running, causes turbocharger surge and thermal cracking of liners and pistons.
- Barred speed ranges: pass through criticals quickly and never run continuously inside them.
Worked example
A shop test gives SFOC 178 g/kWh with fuel LCV 42.7 MJ/kg. Fuel energy per kWh = 0.178 x 42.7 = 7.60 MJ = 7,600 kJ. Thermal efficiency = 3,600 / 7,600 = 47.4 %. If the same engine later burns 190 g/kWh, efficiency has fallen to 3,600 / 8,113 = 44.4 %. Investigate injection timing, scavenge air pressure and fouling before blaming the fuel.
Traps
Comparing SFOC values without correcting for fuel LCV and ambient conditions; treating MCR (maximum continuous rating) as the normal operating point when the continuous service rating is lower; quoting alarm limits as if they were operating limits.