Marine Engineering and Systems
Marine Engineering and Systems covers what a deck officer must genuinely understand about propulsion, steering and auxiliary plant - enough to run the ship safely and to question a decision politely but firmly.
Propulsion
Slow-speed two-stroke diesels drive the propeller directly; medium-speed four-strokes work through reduction gearing. On the fuel side, HFO is heated, separated and filtered, and changeover to low-sulphur distillate before an emission control area needs a planned procedure because viscosity, pumps and seals all change. Scavenge fires, crankcase explosions, fuel valve faults and turbocharger surging are standard oral questions.
Steering gear
SOLAS II-1 requires two independent power units. The main gear must move the rudder from 35° on one side to 30° on the other in not more than 28 seconds with all power units running; the auxiliary or emergency arrangement must move 15° to 15° in 60 seconds. SOLAS V/26 requires testing within 12 hours before departure - bridge remote control, emergency power, changeover procedure, alarms and rudder angle indicators - plus emergency steering drills every three months.
Ancillary systems
Starting air at about 30 bar with capacity for repeated starts; inert gas plant holding tank oxygen below 5 per cent by volume at positive pressure; oily-water separator with the 15 ppm alarm and automatic stopping device; sewage plant, incinerator, ballast water treatment; and the emergency generator, which must take load within 45 seconds, with 30 seconds the usual class target.
Worked example
Fuel of 3.20 per cent sulphur is burned with a scrubber certified to 97 per cent removal. Equivalent sulphur = 3.20 × 0.03 = 0.096 per cent, inside the 0.10 per cent ECA limit, so the ship may enter the area provided washwater and monitoring requirements are met. If removal drops to 95 per cent, the equivalent is 0.16 per cent and the ship must change over to compliant fuel before the boundary.
Traps
Confusing the 28-second and 60-second steering requirements; recording the steering test but not the changeover; quoting 15 ppm without the alarm and automatic stop; and assuming inert gas removes flammable vapour rather than simply keeping oxygen below the level that supports combustion.