MEO Class II · Second Engineer · Concept refresher

Chapter briefs for MEO Class II.

Eleven topics, each in one screen: what the paper actually asks, the formulas and numbers worth carrying, the mistakes that cost marks, and a recall list to run through before you sit. Read the brief, then take the exam on the same topic.

ExamMEO Class II
Topics11 chapter briefs
Read time≈ 6 min each
01 Adv. thermo 02 Propulsion plant 03 Diagnostics & CBM 04 Power management 05 Automation 06 Refrig & HVAC 07 Legislation 08 Maintenance 09 Stability & docking 10 Energy & environment 11 Orals
01 / 11Cycles & heat transfer

Advanced Thermodynamics & Heat Transfer

Class II moves from knowing a cycle to accounting for it. Every mark here is an energy balance: what went in as fuel, what left as work, and where the rest went.

What the paper asks

Cycle efficiency and work output from given pressures and temperatures; steam plant calculations with steam tables; heat exchanger duty and terminal temperatures; boiler efficiency by the direct and indirect methods; exhaust gas economiser performance; and the reasoning behind superheating, feed heating and waste heat recovery.

The concepts, in order

The energy balance is the method. Fuel energy in equals shaft work plus jacket water plus exhaust gas plus radiation. A modern two-stroke turns roughly half of it into work, and the examiner's questions are usually about the other half — which is where waste heat recovery, the economiser and the scavenge air cooler all live.

Cycles. The diesel and dual cycles differ only in how heat is added — at constant pressure, or partly at constant volume. Efficiency rises with compression ratio and falls as the cut-off ratio grows, which is why efficiency drops as an engine is loaded up at fixed revolutions.

Steam plant. Rankine efficiency improves with higher boiler pressure, higher superheat and lower condenser pressure. Superheat matters twice: it lifts efficiency and it keeps the turbine exhaust dry enough not to erode the last-stage blading.

Heat exchangers. Q = U·A·LMTD, with counterflow always giving the larger mean temperature difference for the same terminal temperatures. Fouling shows up as a falling U — which is why a rising terminal temperature difference on a cooler is the first evidence of a dirty tube stack, before any alarm sounds.

Boiler efficiency. The direct method divides steam heat by fuel heat and needs accurate flow measurement. The indirect method sums the losses — dry flue gas, moisture, radiation, unburnt — and subtracts from 100. The indirect method is preferred on board because it also tells you which loss to attack.

Where marks are lost

  • Gauge pressure used in a cycle calculation. Thermodynamics runs on absolute pressure and absolute temperature throughout.
  • Enthalpy taken for saturated steam when the steam is superheated. Read the superheat table at both pressure and temperature.
  • Efficiency quoted against the wrong calorific value. Marine practice normally uses the lower calorific value; state which one you used.
  • Counterflow and parallel flow LMTD interchanged. Check which stream enters at which end before writing the formula.
60-second recall
  1. Absolute pressure, absolute temperature — every time.
  2. η rises with compression ratio, falls with cut-off ratio.
  3. Q = U·A·LMTD; a rising terminal ΔT means fouling.
  4. Indirect boiler efficiency = 100 − sum of the losses.
  5. Roughly 50 % work, 25 % exhaust, 15 % jacket & charge air on a modern two-stroke.
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02 / 11Performance & loading

Propulsion Plant & Performance

The propeller law ties revolutions, torque and power together. Once you can move between them, most performance questions — fouling, heavy running, overload — answer themselves.

What the paper asks

Indicated and brake power from indicator cards and torsionmeter readings; mean effective pressure; the propeller law and what pushes an engine into the overload region; shaft power measurement; slip; and the interpretation of a performance report against sea trial data.

The concepts, in order

The propeller law. Torque varies with the square of revolutions and power with the cube, so a small drop in revolutions is a large drop in power. This is why a fouled hull or a heavy draught shows up as the engine reaching its torque limit before its rated revolutions — the classic heavy running condition.

Power measurement. Indicated power comes from the mean effective pressure over the indicator card; brake power comes from a torsionmeter on the shaft. The difference is mechanical efficiency, typically 85–92 %, and a widening gap points at friction, bearings or a fouled scavenge space.

Load diagram. The engine's permitted operating field is bounded by torque, power and speed limits. Continuous operation to the left of the torque limit is what damages an engine, and it is caused by hull fouling, heavy weather, shallow water or an over-pitched propeller.

Slip. Apparent slip is calculated from the log speed and is contaminated by current; real slip uses speed of advance. A rising real slip with unchanged draught is fouling; a sudden change in apparent slip alone is usually the current or a faulty log.

Shafting. The line must accommodate torsional vibration, thrust and alignment. Barred speed ranges exist because a torsional critical falls there; they are passed through, never dwelt in, and the reason is fatigue of the crankshaft and intermediate shaft, not noise.

Where marks are lost

  • Applying the propeller law to a fixed-pitch and a controllable-pitch propeller identically. A CPP breaks the cubic relation because pitch is now a variable.
  • Comparing SFOC without correcting to reference conditions. Ambient temperature, charge air temperature and calorific value all have to be normalised first.
  • Reading the load diagram as if the limit were power. The damaging limit in heavy running is torque.
  • Treating apparent slip as a hull condition indicator. Only real slip, over time, at similar draught, means anything.
60-second recall
  1. Q ∝ N², P ∝ N³ — the propeller law.
  2. IP from the card, BP from the torsionmeter, and η_mech between them.
  3. Heavy running = torque limit reached before rated revolutions.
  4. Barred speed range is passed through, never held.
  5. Normalise SFOC before you compare it to anything.
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03 / 11Evidence before action

Fault Diagnostics & Condition Monitoring

The examinable skill is reasoning from symptom to cause without opening anything. Every diagnostic question has a chain: what changed, what else would have changed if the obvious cause were right, and what test separates the two.

What the paper asks

Interpretation of indicator and draw cards; exhaust temperature deviation; lube oil analysis results; vibration signatures and what frequency points to what defect; bearing condition assessment; trending and alarm setting; and the reasoning behind planned versus condition-based maintenance.

The concepts, in order

Cards. The power card shows work done; the draw card, drawn on a light spring, magnifies the compression and combustion transition. Late injection, leaking exhaust valve, worn rings and a blocked scavenge port each distort the card in a distinct way — learning those four shapes covers most of the marks in this topic.

Exhaust temperatures. One high cylinder against the mean suggests late or excessive injection or a leaking exhaust valve; all high suggests fouled turbocharger, air cooler or dirty scavenge. Always compare against the mean at the same load, not against an absolute number.

Lube oil analysis. Viscosity rise means oxidation or contamination with heavy fuel; viscosity fall means dilution with distillate. Water content triggers the risk of emulsification and bearing corrosion. Rising iron with rising silicon is abrasive wear from cat fines or ingress, not fatigue.

Vibration. Once-per-revolution vibration is unbalance; twice-per-revolution suggests misalignment; blade rate points to the propeller; bearing defects appear as high-frequency bands with their own characteristic frequencies. Amplitude alone means little — trend against the machine's own baseline.

Condition-based maintenance. Its case is that overhauling to a calendar interval either wastes life or misses a developing fault. It requires measurement, a baseline and a trend, and class will accept it as an alternative survey basis only under an approved scheme.

Where marks are lost

  • Judging exhaust temperature against an absolute limit instead of against the mean of the other units at the same load.
  • Reading a single oil sample as a verdict. One result is a data point; the trend is the finding.
  • Confusing unbalance and misalignment. The distinguishing evidence is axial vibration and the harmonic order, not the amplitude.
  • Proposing to open a unit before the non-invasive tests are exhausted. The examiner is testing judgement, and opening up is the last step, not the first.
60-second recall
  1. Compare against the mean at the same load.
  2. 1× = unbalance, 2× = misalignment, blade rate = propeller.
  3. Viscosity up = oxidation or HFO; down = distillate dilution.
  4. Trend, baseline, then act.
  5. Non-invasive tests first, opening up last.
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04 / 11Load sharing & protection

Electrical Power Management

Three questions recur: how load is shared between alternators, what makes the switchboard trip, and what happens in the ninety seconds after a blackout.

What the paper asks

Real and reactive load sharing and the roles of the governor and the AVR; synchronising conditions and the effect of getting each one wrong; preferential trip and its sequence; protection grading and discrimination; blackout recovery and emergency generator requirements; insulation resistance and the reason marine systems are insulated rather than earthed.

The concepts, in order

Two independent controls. The governor sets real power sharing (kW); the AVR sets reactive power sharing (kVAr). Trying to correct a kVAr imbalance with the governor is the classic error — it moves kW instead and leaves the circulating current where it was.

Synchronising. Equal voltage, equal frequency, correct phase sequence and correct phase angle at the instant of closing. Closing out of phase produces a violent torque transient through the coupling; closing with unequal voltage produces a reactive surge but is far less damaging.

Preferential trip. When the running generators approach overload, non-essential loads are shed in a set order with short time delays — typically air conditioning first, then ventilation and other comfort loads — to buy time before the generator's own overload protection acts.

Discrimination. Protection must clear the fault at the device nearest the fault and no further upstream, achieved by grading current settings and time delays. Loss of discrimination is what turns a single feeder fault into a blackout.

Insulated neutral. Marine distribution is normally insulated from the hull, so a single earth fault does not trip anything — it merely raises an alarm and must be found before a second fault in another phase turns it into a short circuit. This is why earth fault monitoring is a watchkeeping duty, not an alarm to acknowledge and forget.

Where marks are lost

  • Adjusting the governor to correct reactive load sharing. kW is the governor, kVAr is the AVR.
  • Treating a single earth fault as harmless because nothing tripped. It is the second fault that causes the damage.
  • Forgetting the phase sequence check when a generator has been overhauled or re-cabled.
  • Confusing the emergency generator's role with a standby generator's. The emergency set feeds the emergency switchboard on its own protected circuits, and its start must be automatic within the required time.
60-second recall
  1. Governor = kW. AVR = kVAr.
  2. Synchronise on voltage, frequency, sequence, phase angle.
  3. Preferential trip sheds non-essentials before the generator trips.
  4. Discrimination clears the fault nearest to it.
  5. One earth fault is an alarm; two is a short circuit.
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05 / 11Loops & UMS

Automation & Control (Advanced)

Control questions come down to three things: which variable is measured, what the controller does with the error, and what happens when the loop is put in manual.

What the paper asks

P, PI and PID action and the effect of each term; offset and how integral action removes it; cascade and feed-forward control; boiler water level control including shrink and swell; UMS requirements and the alarm philosophy behind them; and the difference between a control system and a safety system.

The concepts, in order

The three terms. Proportional action responds to the size of the error and leaves an offset. Integral action responds to the accumulated error and removes that offset, at the cost of stability. Derivative action responds to the rate of change and anticipates, which helps on slow processes and amplifies noise on fast ones.

Boiler level. Single-element control measures level only and is defeated by shrink and swell — a sudden steam demand lowers drum pressure, the water flashes, the level appears to rise and a single-element controller closes the feed exactly when more water is needed. Three-element control adds steam flow and feed flow so the loop acts on the real mass balance.

Cascade and feed-forward. Cascade puts a fast inner loop inside a slow outer loop — jacket water temperature setting the position of a three-way valve, for example. Feed-forward acts on a measured disturbance before the controlled variable has moved at all.

UMS. Unattended machinery space operation is permitted only with the required alarm coverage, bridge and engineer's alarm extension, a dead-man alarm, fire detection, bilge level monitoring, automatic standby pump start and a functioning main engine control from the bridge. The examiner wants the reasoning — every item exists because an unmanned space cannot be watched.

Control versus safety. A control system holds a variable at a setpoint; a safety system acts when control has failed, and must be independent of it. Sharing a sensor between the two defeats the point, which is why shutdown transmitters are separate from control transmitters.

Where marks are lost

  • Claiming proportional action removes offset. It cannot; only integral action does.
  • Missing shrink and swell in a boiler level question — it is the whole reason three-element control exists.
  • Describing a safety trip as part of the control loop. Independence is the examinable point.
  • Adding derivative action to a noisy, fast loop. It amplifies the noise and makes the valve hunt.
60-second recall
  1. P leaves offset, I removes it, D anticipates.
  2. Three-element level control: level, steam flow, feed flow.
  3. Shrink and swell fool a single-element controller.
  4. Safety systems are independent of control systems.
  5. UMS = alarms, extensions, dead-man, auto standby, bridge control.
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06 / 11Cycles, controls, air

Refrigeration & HVAC (Advanced)

A refrigeration fault is a pressure and temperature story. Read the two gauges and the superheat, and the plant tells you what is wrong before you touch a valve.

What the paper asks

The vapour compression cycle on a p–h diagram; COP and refrigerating effect; superheat and subcooling; capacity control methods; symptoms of undercharge, overcharge, air in the system and a blocked expansion valve; cargo hold and provision room control; and psychrometrics for accommodation air conditioning.

The concepts, in order

The p–h diagram is the answer sheet. Refrigerating effect is the enthalpy rise across the evaporator; work is the enthalpy rise across the compressor; COP is one divided by the other. Every fault moves a specific point on that diagram, so drawing it first turns a memory question into a reading exercise.

Superheat and subcooling. Superheat protects the compressor from liquid carry-over and is set by the expansion valve. Subcooling before the expansion valve increases the refrigerating effect at no extra compressor work — which is why a liquid line that has picked up heat costs capacity.

Reading faults. Low suction pressure with high superheat suggests undercharge or a restricted expansion valve. Low suction with low superheat suggests a blocked evaporator or a fan fault. High discharge pressure with a warm condenser suggests air in the system or insufficient cooling water; air also raises the condensing temperature above what the water temperature can explain, and that discrepancy is the diagnostic.

Capacity control. Cylinder unloading, on-off cycling, hot gas bypass and variable speed all trade efficiency against control stability. Frequent short cycling is hard on motors and is normally what a complaint of “compressor keeps starting” turns out to be.

Psychrometrics. Accommodation comfort depends on dry bulb temperature and relative humidity together. Cooling below the dew point removes moisture, which is why an air conditioning plant dehumidifies as a side effect of cooling, and why reheating after over-cooling is sometimes the only way to hit both targets.

Where marks are lost

  • Quoting COP without saying which effect is useful. A heat pump's COP is one greater than the same machine used as a refrigerator.
  • Diagnosing high head pressure as “dirty condenser” without checking the cooling water outlet temperature. Air in the system gives a condensing temperature the water cannot account for.
  • Confusing superheat with discharge temperature. Superheat is measured at the compressor suction, against the saturation temperature for that pressure.
  • Ignoring the refrigerant when discussing compliance. The regulatory position on R22 and high-GWP refrigerants is part of the answer at management level.
60-second recall
  1. COP = refrigerating effect / work in.
  2. Superheat protects the compressor; subcooling adds capacity free.
  3. Low suction + high superheat = short of refrigerant or restricted TEV.
  4. High head + cool water = air in the system.
  5. Cooling below dew point dehumidifies.
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07 / 11ISM, MLC, PSC

Legislation, ISM/ISPS & Management

Regulatory questions are answered with structure, not recall: which instrument, which chapter, who enforces it, and what evidence proves compliance on the day.

What the paper asks

SOLAS chapter structure and what each covers; the ISM Code elements and the certificates it produces; ISPS levels and the ship security plan; MLC titles and inspection; port state control detention criteria; the survey and certification regime; and the documentary evidence an inspector will ask for.

The concepts, in order

Know the instrument, then the chapter. SOLAS covers safety of life, MARPOL pollution, STCW competence, MLC seafarer employment and living conditions, and Load Line the reserve buoyancy. Naming the right instrument before quoting a requirement is half the mark.

ISM in one line each. A safety management system with a documented policy, defined responsibilities, a designated person ashore with direct access to the highest level of management, emergency preparedness, reporting of non-conformities and accidents, planned maintenance, documentation control, and management review. The DOC belongs to the company, the SMC to the ship.

Non-conformities. A non-conformity is an observed situation where objective evidence shows a specified requirement is not met; a major non-conformity is a serious threat that requires immediate corrective action. Knowing that difference, and that the record is the objective evidence, is what separates a management-level answer from an operational one.

ISPS levels. Level 1 is normal, level 2 heightened, level 3 exceptional and set by the administration for a specific threat. The ship security plan is approved and confidential, and the SSO reports to the CSO.

Port state control. Inspections start with the certificates and the general impression; clear grounds lead to a more detailed inspection; deficiencies are recorded with action codes, and detention follows where a deficiency is serious enough that the ship should not proceed to sea. The engineer's practical defence is that the certificates match the equipment and the records match reality.

Where marks are lost

  • Attributing a requirement to the wrong instrument — oily water separation is MARPOL Annex I, not SOLAS.
  • Confusing the DOC and the SMC. Company and ship respectively.
  • Describing ISPS level 3 as a shipboard decision. It is set by the administration.
  • Answering a management question with an operational answer. At Class II the examiner wants the system, the evidence and the responsibility, not the valve.
60-second recall
  1. Instrument first, then chapter, then requirement.
  2. DOC = company, SMC = ship, both from ISM.
  3. DPA has direct access to the highest management level.
  4. Major non-conformity = serious threat, immediate action.
  5. Detention = the ship should not proceed to sea.
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08 / 11PMS, surveys, dock

Maintenance & Dry-dock Planning

Planning questions reward the same shape every time: scope, sequence, resources, safety, and the record that proves it happened.

What the paper asks

Planned maintenance systems and how class credits them; the survey cycle and continuous machinery survey; dry-dock specification writing; critical spares and stock policy; risk assessment and permit-to-work; job cards and the maintenance record; and the reasoning behind condition-based rather than calendar-based intervals.

The concepts, in order

The PMS is the evidence. A planned maintenance system defines the task, the interval, the responsible rank, the spares and the record. Class approval of a PMS lets machinery surveys be credited from the ship's own records rather than from a surveyor's attendance — but only if the records are contemporaneous and honest.

Survey structure. A five-year renewal cycle with annual and intermediate surveys in between; continuous machinery survey spreads the items across the cycle so roughly one fifth is examined each year. Postponement is possible but must be applied for, not assumed.

The dock specification. Written work by work, each item with scope, access, materials, standard of acceptance and who supplies what. The two failures that cost money are vague scope, which becomes a yard variation order at the yard's price, and missing access work — staging, blanking, gas freeing — that stops the priced job from starting.

Critical spares. The requirement is not the largest possible stock, it is the spares whose absence stops the ship — governed by class and flag minimum lists, by lead time, and by the criticality assessment in the SMS.

Permit to work. Enclosed space entry, hot work, electrical isolation and work aloft each need the hazards identified, the isolation proven, the atmosphere tested where relevant, the duration limited and the permit closed out. In an examination answer, isolation and testing before entry are the two things that must not be missing.

Where marks are lost

  • Describing a PMS as a schedule. It is a schedule plus records plus approval — the records are what class credits.
  • Writing a dock specification without acceptance criteria. “Overhaul as necessary” is a blank cheque.
  • Omitting atmosphere testing before enclosed space entry. This is the single most-penalised omission in the topic.
  • Assuming a survey can simply be postponed. Postponement is granted, not taken.
60-second recall
  1. Task, interval, rank, spares, record — the five fields of a PMS entry.
  2. Renewal every 5 years, annual and intermediate between.
  3. CMS spreads machinery items across the cycle, ~20 % a year.
  4. Dock spec: scope, access, materials, acceptance, supply.
  5. Isolate, test, permit, then enter.
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10 / 11EEXI, CII, MARPOL

Energy Efficiency & Environmental Compliance

The regulatory ground that moves fastest. Answers need the mechanism — what is measured, over what period, and what a poor result actually obliges the ship to do.

What the paper asks

MARPOL annexes and their principal limits; EEXI, CII and the SEEMP; NOx tiers and the operating areas that trigger them; sulphur limits and fuel changeover; oily water separation and the 15 ppm equipment; garbage and sewage requirements; ballast water management standards; and the records that evidence each.

The concepts, in order

Annexes at a glance. Annex I oil, II noxious liquids in bulk, III harmful substances in packaged form, IV sewage, V garbage, VI air pollution. Getting the annex right is the first mark; the limits follow.

EEXI and CII. EEXI is a technical index — a design attribute of the ship as it now exists, calculated once and improved by physical measures such as engine power limitation. CII is operational, calculated each year from fuel consumed and distance sailed, and rated A to E. The two are often confused; the distinction is design versus operation.

SEEMP. The plan that connects them: Part I energy efficiency measures, Part II the data collection plan, Part III the operational carbon intensity plan with targets and, for a ship rated D three years running or E once, a corrective action plan.

NOx and SOx. NOx limits depend on the engine's build date and where the ship is operating — Tier III applies in designated emission control areas. Sulphur is a fuel matter: the global limit with a lower limit in ECAs, met either by compliant fuel or by an approved equivalent such as a scrubber, with the changeover recorded.

Oily water. Discharge of machinery space bilge water requires the 15 ppm equipment in operation, the ship en route, and an automatic stopping device. The oil record book is the legal evidence, and its integrity — every transfer, every discharge, every disposal ashore — is what enforcement actually turns on.

Where marks are lost

  • Confusing EEXI with CII. One is technical and fixed, the other operational and annual.
  • Quoting a NOx limit without the engine's build date and the operating area. Both determine the tier.
  • Describing the 15 ppm limit as the only condition for discharge. En route, equipment in operation and the automatic stopping device all apply.
  • Treating the oil record book as paperwork. It is the evidence, and entries must be contemporaneous and signed.
60-second recall
  1. Annexes I–VI: oil, NLS, packaged, sewage, garbage, air.
  2. EEXI = technical, once. CII = operational, annual, rated A–E.
  3. D three years running or E once ⇒ corrective action plan.
  4. 15 ppm, en route, equipment running, auto stop.
  5. Tier III in ECAs; sulphur 0.50 % global, 0.10 % in ECAs.
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11 / 11Judgement under pressure

Second Engineer Orals & Scenarios

The oral is not a memory test. The examiner is checking whether you make safe decisions in the right order and can say why — out loud, without prompting.

What the paper asks

Scenario handling: engine room fire, blackout, main engine failure in confined waters, flooding, a crew injury, an oil spill during bunkering. Also handover, taking over a new ship, planning a job, and how you would satisfy yourself that something is safe before it is used.

The concepts, in order

Answer in a structure. Immediate actions to make it safe, inform the bridge and the master, muster and account for people, contain, then investigate and repair, then report and record. Almost every scenario answer fits that shape, and the examiner is listening for the order more than the detail.

People before plant, always. The first sentence of any emergency answer accounts for personnel. A candidate who starts by describing a valve has answered a different question from the one asked.

Say why, not just what. “I would stop the purifier” is half an answer; “I would stop the purifier because the oil is being fed to a tank I am no longer confident about, and I want the source isolated before I sound it” is the whole one.

Know your own ship. Capacities, starting air pressure, number of starts available, emergency generator start sequence, fire pump arrangement, the emergency fire pump's location and how it is started, and where every isolating valve is. These are the questions that separate candidates.

Admit the limit. Saying you would consult the manual, the class surveyor or the company technical superintendent is a strong answer when the situation calls for it. Inventing a figure is the one thing an examiner cannot forgive.

Where marks are lost

  • Starting with the machinery instead of the people.
  • Giving a procedure without the reason behind it.
  • Guessing a regulatory number. Say you would verify it, and where.
  • Forgetting to inform the bridge. In almost every scenario it is an early action, and its absence is noticed.
60-second recall
  1. Safe → inform → muster → contain → repair → report.
  2. People first, plant second.
  3. Every action gets a reason.
  4. Know your own ship's numbers.
  5. Never invent a figure.
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