Marine Machinery, Systems and Propulsion Plant
What this domain tests
Engine rating and fuel economics, fuel and lube oil treatment, essential auxiliary systems, steering gear requirements and propulsion plant redundancy. Expect questions that link a machinery failure to a SOLAS or MARPOL requirement.
Rating and fuel
- MCR is the maximum continuous rating; NCR is the normal service rating. SFOC in g/kWh is quoted at a stated load and lower heating value.
- The layout diagram combines the engine limits, the light-running propeller curve and the heavy-running curve; margins must keep the operating point inside the limits.
- Fuel to ISO 8217 with grade-specific viscosity, density and cat fines; sulphur limited to 0.50% globally since 1 January 2020 and 0.10% in ECAs, with equivalent abatement (scrubbers) permitted.
- Treatment train: settling tank, purifier, service tank, final filter, with viscosity control by heating.
Essential systems
Cooling water, lube oil, compressed air, fuel, ballast water treatment to the D-2 standard, oily water separator (15 ppm alarm and automatic stop), sewage treatment, incinerator, and the fire and bilge systems. Steering gear under SOLAS II-1 Regulation 29 requires two independent power units; after a single failure the rudder must move from 35 degrees one side to 30 degrees the other in not more than 28 seconds.
Worked example
An engine develops 8,000 kW at an SFOC of 175 g/kWh. Fuel flow = 8,000 x 175 = 1,400,000 g/h = 1,400 kg/h, or 33.6 t/day. At USD 600/t that is about USD 20,160 per day. A 3% SFOC improvement through tuning saves roughly 1 t/day, so fuel economics, not maintenance cost, dominates the operating budget.
Traps
Confusing MCR with NCR; quoting SFOC without its reference conditions and lower heating value; assuming scrubber discharge is unrestricted (washwater rules apply); forgetting the 28-second steering criterion applies to a single failure case; ignoring fuel compatibility and stability when switching grades.