MARINA Second Engineer / Chief Engineer Theoretical Exam flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Diesel cycle thermal efficiency

Efficiency = 1 − (1/r^(γ−1)) · (ρ^γ − 1)/(γ(ρ − 1)), where r is compression ratio, ρ the cut-off ratio, and γ the specific heat ratio. Higher compression ratio improves efficiency.

Brake specific fuel consumption

Mass of fuel consumed per unit of brake power per hour, usually in g/kWh. Large slow-speed two-stroke engines typically achieve 160–175 g/kWh at rated load.

Propeller law

For a fixed-pitch propeller, absorbed power varies with the cube of shaft speed and thrust with the square. A 10% rpm increase raises power demand by about 33%.

Governor speed droop

The percentage speed rise from full load to no load at rated setting. Propulsion engines typically use 3–5% droop; isochronous mode (zero droop) is used for alternators.

Starting air requirement

SOLAS requires sufficient starting air for at least 12 consecutive starts of a reversible engine, or 6 for a non-reversible engine, normally from air bottles at about 30 bar.

Crankcase oil mist detector

A device that samples crankcase atmosphere and alarms at about 2.5% of the lower explosive limit. On alarm, reduce load and investigate; never open doors before cooling.

Pump affinity laws

For a centrifugal pump at constant impeller diameter, flow varies with speed, head with speed squared, and power with speed cubed. These laws guide speed control and throttling decisions.

Net positive suction head

NPSH available equals atmospheric minus vapour pressure head, plus static suction head, minus friction losses. It must exceed the pump's NPSH required to avoid cavitation.

Boiler low-water interlock

A safety device that cuts off fuel to the boiler when water level falls below a safe limit. Firing a boiler with low water level risks overheating and explosion.

Steering gear drill interval

SOLAS requires emergency steering drills every three months, including communication with the bridge and operation of the auxiliary steering gear from the steering flat.

Three-phase power formula

Active power P = √3 · line voltage · line current · power factor. A low power factor increases current for the same kW, raising cable and generator loading.

Synchronous generator paralleling

Before closing the breaker, match voltage, frequency, phase sequence, and phase angle. After paralleling, governor droop determines how active load is shared between generators.

Insulation resistance minimum

Low-voltage circuits should normally read at least 1 MΩ when tested at 500 V DC. Readings are recorded and trended; a falling trend indicates moisture or deterioration.

IT earthing system

A distribution with no direct neutral earth, standard on ships. A single earth fault does not trip the circuit but must be found and cleared before a second fault occurs.

STCW rest hour limits

A minimum of 10 hours rest in any 24-hour period and 77 hours in any 7-day period. Rest may be split into at most two periods, one of at least 6 hours.

UMS alarm response

In an unattended machinery space, the engineer on call must respond within the time stated in standing orders. Alarms and safety systems are tested before entering UMS mode.

Bridge order acknowledgement

The engineer repeats the order, executes it, and reports back. This closed-loop communication prevents misunderstanding during manoeuvring and is standard watchkeeping practice.

Bunkering checklist items

Agreed transfer rate, tank soundings before and after, scuppers plugged, overflow tank monitored, communication with the barge, and drip trays in place.

Condition-based maintenance

Maintenance triggered by measured condition rather than fixed intervals, using vibration analysis, oil analysis, thermography, and performance trending to decide when intervention is needed.

Oil analysis parameters

Viscosity, water content, total base number, insolubles, and wear metals such as iron, copper, lead, tin, and silicon. Trends over time matter more than single readings.

Class special survey interval

Special surveys are normally conducted at five-year intervals, with annual and intermediate surveys in between. Continuous survey machinery spreads items across the cycle.

Oily water separator limit

MARPOL Annex I permits discharge of processed bilge water only at 15 ppm or less, through an approved separator with alarm and automatic stopping device, outside special areas.

MARPOL sulphur limits

Fuel sulphur must not exceed 0.50% m/m globally and 0.10% m/m in emission control areas. Compliance is by low-sulphur fuel, scrubber, or alternative fuel, with records.

Oil record book entry

Each transfer, disposal, or separator operation must be recorded without delay and signed. Falsifying entries is a criminal offence in most jurisdictions.

Ballast water management

The BWM Convention requires D-1 exchange or D-2 treatment, a ballast water management plan, a record book, and a valid certificate on board.

SOLAS chapter structure

Chapter II-1 covers subdivision and machinery, II-2 fire safety, IX the ISM Code, and XI-1/2 surveys and port state control. Engineers should know which chapter applies.

ISM Code requirement

A Safety Management System with documented procedures, a designated person ashore, and defined master's authority. Non-conformities are recorded and closed out.

Port state control detention

When deficiencies are serious, the port state may detain the ship until rectified. Detentions are published in regional databases and affect future inspections.

Metacentric height formula

GM = KM − KG. Positive GM gives initial stability; the GZ curve area gives dynamical stability, and IMO criteria require area to 30° of at least 0.055 m·rad.

Free surface effect

Liquid in a partly filled tank reduces effective GM by free surface correction equal to the tank's second moment of area times density divided by displacement. Subdivision reduces it.

Fire classes

Class A solid, B liquid, C gas, D metal, and F cooking oil. Fixed systems include CO2, foam, water mist, and dry powder, chosen to suit the fuel and space.

Enclosed space entry testing

Test oxygen (about 20.9%), hydrocarbons, carbon monoxide, and hydrogen sulphide before entry. Continuous monitoring and a standby person at the entrance are required.