BD Marine Engineer Class 2 (Second Engineer) cheat sheet

Indicated power (kW) = (pm·L·A·N·n)/60,000 where pm is mean indicated pressure in bar, L stroke in m, A piston area in m², N rev/min, n number of power strokes per revolution.

Brake thermal efficiency = brake power / (fuel mass flow × lower calorific value); typical large two-stroke diesel values are 48-52% at MCR.

Specific fuel consumption (g/kWh) = fuel flow (g/h) / brake power (kW); SFOC rises sharply below about 50% load, so prolonged light-load running fouls exhaust economy.

Compression ratio = (swept volume + clearance volume) / clearance volume; a falling compression pressure on one unit indicates worn rings, leaking valves, or scavenge air loss.

Indicator diagrams: the peak pressure position (after TDC) and the expansion line shape reveal injection timing; a low peak with high exhaust temperature suggests late or retarded injection.

Crankcase oil mist detector alarm: stop the engine, do not open crankcase doors, allow settling and ventilation, then investigate bearing and piston condition before restart.

Air-to-fuel ratio for complete combustion of a typical marine diesel is about 14.5:1 stoichiometric; scavenge air excess of 2.0-2.5 times is normal at full load.

Turbocharger surging at low load is caused by compressor operation left of the surge line; corrective actions include reducing load rate, cleaning the compressor, and checking exhaust back pressure.

Propeller law: power varies with speed cubed (P ∝ N³) and thrust with speed squared for a fixed-pitch propeller in calm water; doubling revs needs roughly eight times the power.

Engine layout diagram is bounded by L1 (torque/speed limit), L2 (mean effective pressure limit), L3 (maximum speed), and L4 (overspeed); continuous operation is limited to the MCR point and the specified service point.

Two-stroke crosshead engines use a stuffing box and diaphragm to keep cylinder oil out of the crankcase; cylinder oil is a separate total-loss system with feed rate set by sulphur content of the fuel.

Four-stroke trunk piston engines share crankcase and cylinder lubrication; fuel sulphur above 0.5% requires cylinder oil with base number matched to neutralise the resulting acid.

A controllable-pitch propeller maintains near-constant engine speed across the load range; pitch is reduced at high load to keep combustion pressure within limits.

Shafting components in order from engine: thrust bearing, intermediate shafting, stern tube bearing, propeller shaft; the thrust bearing transmits propeller thrust to the hull.

Torsional vibration is controlled by a detuner or viscous damper; a barring gear must be engaged when the engine is stopped to prevent thermal bowing of the crankshaft.

Manoeuvring: the engine must be capable of reversing from full ahead to full astern within the time specified by the classification society, typically about 15-30 seconds of air start availability.

Fuel oil treatment: settling tank, then purifier (centrifuge) at about 98°C for heavy fuel, with a viscosity at injection of 10-15 cSt; viscosity is the controlled variable, not temperature.

Boiler feedwater: maintain alkalinity (pH 10.5-11.5), phosphate treatment for scale control, and continuous blowdown to limit dissolved solids; test chloride to detect condenser leakage.

Fresh water generator uses engine jacket water as heat source; output falls as jacket water temperature falls, so it is interlocked with main engine load.

Air compressor intercoolers and aftercoolers reduce air temperature to condense moisture; drain traps must be blown regularly and safety valves tested.

Bilge system: oily water separator must alarm and automatically stop discharge when effluent exceeds 15 ppm; the 15 ppm monitor is a required pollution-prevention fitting.

Steering gear: two independent power-actuating systems required for tankers; the changeover must be possible within 45 seconds and the rudder must move from 35° one side to 30° the other within 28 seconds.

Pumps: centrifugal pumps are primed before starting and must not run dry; positive displacement pumps require a relief valve on the discharge and must never be started against a closed valve.

Refrigeration: the expansion valve controls superheat at the evaporator outlet; a frosted suction line or high superheat indicates undercharge or a restricted valve.

Three-phase power P = √3 × V × I × power factor; apparent power (kVA) differs from real power (kW) by the power factor, typically 0.8 for alternators.

Alternator paralleling requires matching voltage, frequency, phase sequence and phase angle; the synchroscope must be rotating slowly in the fast direction before the breaker is closed.

Load sharing between paralleled alternators is set by governor speed droop; reactive (kVAr) sharing is set by excitation and voltage droop.

Insulation resistance: minimum acceptable value for a 440 V system is about 1 MΩ at 500 V DC; test with the circuit isolated and earthed before and after.

Preferred tripping / discrimination: protective devices are graded so the downstream breaker clears the fault first; a loss of discrimination causes a total blackout.

Bridge control and engine-room control are interlocked; transfer of control must be done at dead slow and acknowledged at both stations.

Unmanned machinery space (UMS) requirements: alarm and safety systems must be self-monitoring, with a dead-man alarm on the engineer's call system and a fire detection system that alarms on the bridge.

Programmable logic controllers: watchdog timers detect program failure; input/output modules are isolated from the field by opto-couplers to protect the processor.

Free surface effect reduces metacentric height GM; it is proportional to the second moment of area of the liquid surface divided by the ship's displacement, so subdivision of tanks limits the loss.

Initial stability: GM = KM − KG; positive GM gives a righting moment, and GZ = GM × sin θ for small angles of heel.

Load line marks: the summer load line is the reference; the tropical mark is above it and the winter mark below by the tabular freeboard difference.

Watertight subdivision: collision bulkhead must be located not less than 0.05L and not more than 0.08L from the forward perpendicular.

Double bottom height is at least B/20 or 760 mm, whichever is greater, and the tank top must not be lower than the required minimum.

Watchkeeping: the engineer of the watch must be physically present and must not leave the machinery space unattended where it is required to be manned; handover includes fuel, water, temperatures, running machinery and standing orders.

Bunkering watch: continuous monitoring of tank levels, agreed communication with the supplier, scuppers plugged and drip trays in place, and a pre-bunkering checklist signed by both parties.

Engine-room log entries must record time, event, and readings at intervals; the log is a legal document admissible in casualty investigation.

MARPOL Annex I: oily water separator 15 ppm limit, oil record book entries, and prohibition of any discharge within special areas.

MARPOL Annex VI: global sulphur limit 0.50% m/m since 1 January 2020, and 0.10% in Emission Control Areas; non-compliant fuel requires an approved scrubber.

NOx Tier III applies to ships built on or after 1 January 2016 when operating in NOx Emission Control Areas; compliance is by engine internal measures or SCR.

Ballast water management: D-1 exchange or D-2 treatment; the Ballast Water Management Plan and record book are mandatory, and exchange is at least 200 nautical miles from land where practicable.

Garbage: MARPOL Annex V prohibits discharge of plastics anywhere; food waste discharge is permitted only outside specified distances from land and after comminution.

SOPEP and the Shipboard Oil Pollution Emergency Plan must be available on board; drills and records are required, and the plan must be approved by the flag administration.

Fire triangle and fixed systems: CO2 total flooding requires the space to be sealed and all personnel accounted for before release; the alarm and time delay precede discharge.

Enclosed space entry: atmosphere tested for oxygen (19.5-23.5%), hydrocarbons and toxic gases, permit issued, standby man posted, and rescue equipment at the entrance.

Planned maintenance system intervals are based on running hours, calendar time, or condition monitoring; condition-based maintenance uses vibration, oil analysis and thermography to trigger work.

Vibration analysis: bearing defects show characteristic frequencies at ball pass and cage frequencies; unbalance shows a once-per-revolution peak, misalignment shows a twice-per-revolution peak.

Crankcase oil analysis looks for water, insolubles, viscosity change, and wear metals (iron, copper, chromium, lead, tin); trending matters more than any single reading.

Steel designation: the number after the letter indicates carbon content in hundredths of a percent; a suffix such as 'K' or 'N' indicates killed or normalised condition.

Welding: electrodes must be dried per the manufacturer's specification; low-hydrogen electrodes for high-strength steel prevent hydrogen-induced cracking.

Bearing clearance is checked with a lead wire or feeler gauge; white metal bearings are scraped to a contact pattern of about 2-3 bearing points per square inch.

Torque = force × radius; a torque wrench must be calibrated, and bolt tightening is done in a star or diagonal sequence to distribute load evenly.

Pipe fittings: flanges are matched by pressure rating and gasket type; a spiral-wound gasket requires full face contact and correct bolt loading to seal.

STCW requires the engineer officer in charge of a watch to hold a certificate of competency; watchkeeping duties and rest hours are specified, with minimum 10 hours rest in any 24-hour period.

ISM Code requires documented procedures, a designated person ashore, and a safety management system with internal audits and master's review.

ISPS Code: access control, ship security officer, ship security plan, and security levels 1-3 with corresponding measures.

MARPOL and the oil record book: false entries are a criminal offence; entries must be made at the time of the operation and signed by the officer in charge.

The engineer's responsibility for the seaworthiness of machinery is shared with the master; defects affecting safety must be reported to the master and recorded, and the classification society informed where required.

Port State Control: deficiencies can lead to detention; the engineer must be able to produce certificates, the oil record book, and maintenance records on demand.

Muster list and emergency duties: each crew member has an assigned station; the engineer's duties include emergency generator start, fire pump operation, and machinery shutdown.

Statutory certificates for machinery: the International Oil Pollution Prevention Certificate, the Engine International Air Pollution Prevention Certificate, and the Safety Equipment Certificate are inspected at survey.