Intermediate Marine Engineering interview questions

150 questions with answers (MAR-151 to MAR-300). Try each one aloud before reading the answer.

Ship Construction & Naval Architecture

MAR-151 · Why do bulkheads matter?

Watertight bulkheads split the hull into compartments, so flooding stays local and the ship keeps buoyancy and stability after damage. They also add transverse strength and act as fire barriers.

MAR-152 · What are hogging and sagging?

Hogging happens when the middle is supported by a wave crest and the ends sag, putting the deck in tension and the bottom in compression. Sagging is the reverse, with the ship supported at the ends by two crests.

MAR-153 · Why is the ship's hull treated as a box girder?

The deck and bottom plating act as flanges, and the side shell acts as webs, resisting longitudinal bending. Deck and bottom therefore see the highest bending stresses.

MAR-154 · What is the purpose of the collision bulkhead?

It is the forward watertight bulkhead that keeps flooding confined to the fore peak if the bow is damaged in a collision. It has strict limits on openings.

MAR-155 · What is panting and how is it resisted?

Panting is the in-and-out flexing of bow and stern plating caused by varying water pressure. It is resisted by panting beams, stringers, breasthooks and closer frame spacing at the ends.

MAR-156 · What is pounding (slamming)?

Heavy impact of the forward bottom on the sea when the bow re-enters the water in head seas. The forward bottom is strengthened with extra floors and thicker plating.

MAR-157 · Why do tankers have double hulls?

MARPOL requires double hulls for oil tankers so that a breach of the outer shell from collision or grounding does not release oil, because a void or ballast space separates cargo from the sea.

MAR-158 · What is the midship section modulus?

The section modulus of the hull girder at midships (Z = I/y). Bending stress is σ = M/Z, so class rules set a minimum Z to keep stress within limits.

MAR-159 · What is a cofferdam?

A narrow empty space between two bulkheads that separates tanks holding different liquids, such as oil and fresh water, to stop contamination by leakage.

MAR-160 · What is the bilge keel?

A long fin fitted along the turn of the bilge on each side. It damps rolling by creating eddies and adds no significant resistance if aligned with flow.

MAR-161 · What is the waterplane area coefficient (Cw)?

The ratio of waterplane area to the rectangle of length × beam: Cw = Aw/(L·B). It affects TPC and transverse stability.

MAR-162 · What is the midship section coefficient (Cm) and prismatic coefficient (Cp)?

Cm = Am/(B·T), the fullness of the midship section. Cp = ∇/(Am·L) = Cb/Cm, the distribution of volume along the length, which strongly affects wave resistance.

MAR-163 · Why are ships dry-docked periodically?

To inspect and repair the underwater hull, propeller, rudder, stern tube seals, sea chests and valves, renew antifouling, and meet class bottom survey requirements.

Ship Stability

MAR-164 · What is metacentric height (GM)?

The vertical distance from the centre of gravity G to the transverse metacentre M: GM = KM − KG. Positive GM means the ship is initially stable, and righting lever at small angles is GZ = GM·sinθ.

MAR-165 · What is ballast water used for?

To control draft, trim, list and stability when the ship is light, keep the propeller and rudder immersed, and reduce hull bending stresses.

MAR-166 · How is BM calculated?

BM = I/∇, where I is the second moment of the waterplane area about the centreline and ∇ is the displaced volume. For a box-shaped vessel, BM = B²/(12T).

MAR-167 · How does G move when a weight is added or shifted?

Shifting weight w by distance d moves G parallel to it by GG₁ = w·d/Δ. Adding weight moves G towards the added weight by w·d/(Δ + w).

MAR-168 · What is the inclining experiment?

A test where known weights are shifted across the deck and the heel angle is measured. GM = w·d/(Δ·tanθ), from which the lightship KG is found.

MAR-169 · What is the GZ curve?

A plot of righting lever against heel angle. It shows maximum GZ, angle of vanishing stability, range of stability and the area under the curve (dynamic stability).

MAR-170 · What is dynamic stability?

The work done in heeling the ship to a given angle, equal to displacement × area under the GZ curve up to that angle. It measures the ship's ability to absorb energy from wind and waves.

MAR-171 · What is the angle of loll?

An angle at which a ship with a small negative GM floats, because as it heels, the waterplane widens and G and the line of buoyancy line up again. The ship flops between port and starboard loll angles.

MAR-172 · What is MCTC?

Moment to change trim by one centimetre: MCTC = Δ·GM_L/(100·L). Change of trim (cm) = trimming moment (t·m) / MCTC.

MAR-173 · What is the longitudinal centre of flotation (LCF)?

The centroid of the waterplane, about which the ship trims. A small weight loaded over the LCF changes mean draft without changing trim.

MAR-174 · What is the fresh water allowance (FWA)?

The change in draft when a ship moves from seawater (1.025 t/m³) to fresh water (1.000 t/m³). FWA (mm) = Δ / (4 × TPC), with Δ in tonnes and TPC in seawater.

MAR-175 · How is the rolling period related to GM?

Roll period T = 2πk/√(g·GM), where k is the radius of gyration. A larger GM gives a shorter, quicker roll, and a smaller GM gives a slow, long roll.

MAR-176 · What are hydrostatic curves?

Plots or tables of displacement, TPC, KB, KM, LCB, LCF and MCTC against draft. Officers use them for loading and stability calculations.

Resistance & Propulsion

MAR-177 · What is propeller cavitation?

When local pressure on the blades falls below vapour pressure, vapour bubbles form and then collapse violently. This causes erosion pitting, noise, vibration and loss of thrust.

MAR-178 · What is the wake fraction?

Water behind the hull is dragged along, so the propeller sees a lower inflow speed Va. The Taylor wake fraction is w = (V − Va)/V.

MAR-179 · What is thrust deduction?

The propeller's suction increases hull resistance, so thrust T must exceed bare-hull resistance R. Thrust deduction factor t = (T − R)/T.

MAR-180 · What is hull efficiency?

ηH = (1 − t)/(1 − w). It can exceed 1 because the propeller recovers some wake energy.

MAR-181 · What is the quasi-propulsive coefficient (QPC)?

QPC = PE/PD = ηH × ηO × ηR, the ratio of effective power to power delivered at the propeller. Typical values are around 0.6–0.75.

MAR-182 · How does power vary with ship speed?

Approximately, power is proportional to the cube of speed (P ∝ V³) over the normal speed range. Fuel per day therefore rises steeply with speed.

MAR-183 · What is the Admiralty coefficient?

C = Δ^(2/3)·V³/P. It is assumed constant for a ship at similar conditions and is used to estimate power for a new speed or displacement.

MAR-184 · How is apparent slip calculated?

Apparent slip = (P·N − V)/(P·N), where P is pitch, N is revolutions per unit time and V is ship speed. Real slip uses the wake speed Va instead of V.

MAR-185 · What is Froude number and why does it matter?

Fn = V/√(g·L). It governs wave-making resistance, and model tests are run at the same Froude number as the full ship.

MAR-186 · What is the difference between right-hand and left-hand propellers?

A right-hand propeller turns clockwise when viewed from astern in ahead motion. It tends to push the stern to starboard and the bow to port when going astern from rest.

MAR-187 · What is the function of the stern tube seal?

To prevent seawater entering the ship and stop stern tube lubricating oil leaking out. Lip seals or face seals are used at both forward and aft ends.

MAR-188 · What is the shaft line alignment?

The setting of bearing heights so that bearing loads, shaft stresses and gear or crankshaft deflections are within limits under operating conditions.

MAR-189 · What are the main propeller blade terms?

Diameter, pitch, number of blades, blade area ratio, skew and rake. Skew reduces vibration, and blade area ratio is set to avoid cavitation.

Marine Diesel Engines

MAR-190 · How does a turbocharger increase engine power?

The exhaust turbine drives a compressor that raises scavenge air pressure and density. More air mass in the cylinder allows more fuel to burn per cycle, increasing mean effective pressure.

MAR-191 · What is the indicator diagram used for?

It plots cylinder pressure against stroke or crank angle. It is used to find indicated power, compression and peak pressures, and to diagnose injection timing faults.

MAR-192 · How is indicated power of a two-stroke engine calculated?

IP = pmi × L × A × n × k, where pmi is mean indicated pressure, L stroke, A piston area, n revolutions per second and k number of cylinders. Use n/2 for a four-stroke.

MAR-193 · What is a scavenge fire?

A fire in the scavenge space caused by blow-by of hot gas igniting oil residues from excessive cylinder oil or poor combustion. Signs are high scavenge and exhaust temperatures and surging turbocharger.

MAR-194 · What is a crankcase explosion?

Oil mist formed by a hot spot (such as an overheated bearing) mixes with air and is ignited. A primary explosion can draw in air and cause a more violent secondary explosion.

MAR-195 · How are crankcase explosions prevented?

By oil mist detectors, bearing temperature monitoring, crankcase relief valves with flame arresters, and not opening the crankcase until the engine has cooled after a hot spot is suspected.

MAR-196 · What is turbocharger surging?

Unstable compressor flow where air flow reverses momentarily, giving a loud bang or barking noise. It happens when pressure ratio is too high for the air flow, for example from fouled air coolers or blocked filters.

MAR-197 · Why is crankshaft deflection measured?

Deflection readings between crank webs show bearing misalignment or wear in the main bearings. Excessive values can cause crankshaft fatigue.

MAR-198 · What is the purpose of jacket cooling water treatment?

To prevent corrosion and scale in the cooling spaces. Nitrite-borate inhibitors are common, with checks on concentration, pH and chlorides.

MAR-199 · What is the purpose of the starting air distributor?

It admits starting air to each cylinder's air start valve at the right crank angle, in firing order, so the engine turns in the desired direction.

MAR-200 · Why is the exhaust valve rotated in two-stroke engines?

Rotation, often by vanes on the stem driven by exhaust gas, evens out temperature and wear around the seat and removes deposits, extending valve life.

MAR-201 · What is the electronically controlled (ME/RT-flex) engine?

A two-stroke engine without a camshaft, where fuel injection and exhaust valve timing are controlled electronically via hydraulic or common-rail systems. This allows optimisation over the load range.

MAR-202 · What is the fuel injection pump timing effect?

Early injection raises peak pressure and NOx but improves efficiency. Late injection lowers peak pressure but raises exhaust temperature and fuel consumption.

Marine Boilers & Steam Systems

MAR-203 · How is a boiler gauge glass blown through?

Close the steam and water cocks, open the drain, then open and close the steam cock and water cock in turn to blow each passage clear. Finally close the drain and open both cocks, checking the level returns quickly.

MAR-204 · What are priming and foaming in boilers?

Priming is the carry-over of water slugs with steam, often from high water level or sudden steam demand. Foaming is bubbles forming on the water surface due to oil, suspended solids or high dissolved solids.

MAR-205 · What is the accumulation of pressure test?

With the stop valve closed and burner firing at full rate, the safety valves must stop pressure rising more than 10% above working pressure. It proves the valves have enough relieving capacity.

MAR-206 · What are the main boiler water tests?

Alkalinity (pH), chloride, phosphate, hardness and oxygen scavenger reserve (such as hydrazine or sulphite), plus conductivity or total dissolved solids.

MAR-207 · Why is high chloride in boiler water a concern?

It shows seawater contamination, often from a leaking condenser or drain cooler. Chlorides cause corrosion and scale, so the source must be found and blowdown increased.

MAR-208 · What is a soot fire in the exhaust gas boiler?

Ignition of soot deposits on the economiser tubes, usually during low load running. It is prevented by regular soot blowing and good combustion.

MAR-209 · What causes boiler tube failure?

Overheating from scale or low water, corrosion from oxygen or low pH, caustic attack, erosion and soot fires.

MAR-210 · What is the purpose of the feed water deaerator or hot well temperature?

Keeping feed water hot drives out dissolved oxygen and carbon dioxide, which cause pitting corrosion. Chemical oxygen scavengers remove what remains.

MAR-211 · What is boiler water circulation?

Water moves from the cooler downcomer tubes to the heated riser tubes due to density differences. Good circulation keeps tubes wetted and cooled.

MAR-212 · What is a superheater and why is it protected at start-up?

A tube bank that heats saturated steam above saturation temperature. At start-up, it has no steam flow to cool it, so drains and vents are opened and firing rate kept low.

MAR-213 · What is a steam condenser and why is vacuum maintained?

It condenses exhaust steam to water for reuse. Low back pressure (vacuum) increases the enthalpy drop available in turbines and so raises cycle efficiency.

MAR-214 · What is the function of the boiler's low water level alarm and trip?

It warns, then shuts off the burner, if water falls too low, protecting tubes and furnace from overheating.

MAR-215 · How is fuel atomised in a boiler burner?

By pressure jet, rotary cup or steam/air assisted atomisers. Fine droplets mix with combustion air for complete burning.

Auxiliary Machinery (Pumps, Purifiers, Compressors, FWG)

MAR-216 · How does a fresh water generator work?

Jacket cooling water heats seawater in the evaporator under vacuum (made by an ejector), so it boils at low temperature, typically about 40–60 °C. The vapour condenses in a seawater-cooled condenser and the distillate is pumped out under salinity monitoring.

MAR-217 · Why is the FWG not used near the coast?

Coastal and harbour water may be contaminated with sewage and industrial pollution. Common practice is not to run it within about 20 nautical miles of land.

MAR-218 · How is the correct purifier gravity disc selected?

Using the manufacturer's nomogram with fuel density and separating temperature. Too large a disc pushes the interface outward and loses oil to the water outlet; too small lets water pass with the oil.

MAR-219 · What causes a purifier to lose its water seal?

Low or no sealing water, too large a gravity disc, too high a feed temperature or rate, or leaking bowl seals. Oil then escapes through the water outlet.

MAR-220 · What law governs separation in a purifier?

Stokes' law: settling velocity v = d²(ρp − ρl)·g/(18μ). Centrifuging replaces g with ω²r, and heating lowers viscosity μ, both speeding separation.

MAR-221 · Why is heating important before purification?

Heating reduces viscosity and increases the density difference between oil and water, which improves separation efficiency.

MAR-222 · What safety devices are on a main air compressor?

Relief valves on each stage, a fusible plug or temperature trip on the discharge, a bursting disc on the cooler water side, low lube oil pressure trip and automatic drains.

MAR-223 · Why is the air compressor started unloaded?

Opening the drains or unloaders reduces starting torque on the motor and clears condensed water from the coolers.

MAR-224 · What is NPSH and why does it matter?

Net positive suction head is the absolute pressure at the pump inlet above vapour pressure. If available NPSH is less than required, the pump cavitates.

MAR-225 · How does an oil content meter work?

It measures light scattering or absorption in a sample of the OWS discharge. Above 15 ppm it alarms and a three-way valve returns the water to the bilge tank.

MAR-226 · Why are screw pumps used for lube oil and fuel?

They give smooth, pulsation-free flow, handle high-viscosity liquids and are self-priming.

MAR-227 · How does a reverse osmosis plant make fresh water?

High-pressure seawater is pushed through semi-permeable membranes that pass water but reject most dissolved salts. Pre-filtration protects the membranes.

MAR-228 · What are the main types of steering gear and their requirements?

Ram type and rotary vane type electro-hydraulic gears. SOLAS requires the main gear to move the rudder from 35° on one side to 30° on the other within 28 seconds at the deepest draft and maximum ahead service speed.

Marine Electrical Systems

MAR-229 · What conditions must be met before paralleling a generator?

Same voltage, same frequency (incoming slightly faster), same phase sequence and phase angle in step. The breaker is closed as the synchroscope pointer approaches 12 o'clock moving slowly clockwise.

MAR-230 · What happens if a generator is paralleled out of phase?

Large circulating currents and torque shocks occur, which can damage couplings and windings and trip breakers, possibly causing a blackout.

MAR-231 · What is reverse power protection?

A relay that trips a generator breaker when power flows into the generator, making it run as a motor. This occurs if its prime mover loses fuel, and it protects the engine and the busbar.

MAR-232 · What is preferential tripping?

Automatic shedding of non-essential loads (such as galley, air conditioning) on generator overload, so essential services like steering and propulsion auxiliaries stay powered.

MAR-233 · How is load shared between paralleled generators?

Active (kW) load is shared by adjusting governor fuel settings. Reactive (kVAr) load is shared by the automatic voltage regulators adjusting excitation.

MAR-234 · What is the role of the AVR?

The automatic voltage regulator controls generator excitation to keep terminal voltage constant as load and power factor change.

MAR-235 · What SOLAS requirements apply to the emergency generator?

It must start automatically and connect to the emergency switchboard within 45 seconds of main power failure, and supply emergency loads for 18 hours on cargo ships or 36 hours on passenger ships.

MAR-236 · How is an earth fault located on an insulated system?

By watching the earth lamps or insulation monitor while briefly isolating circuits one at a time, starting with non-essential feeders, until the reading returns to normal.

MAR-237 · Why are star-delta starters used?

Starting in star reduces the phase voltage to 1/√3 of line voltage, which cuts starting current and torque to one third of direct-on-line values.

MAR-238 · What is the minimum acceptable insulation resistance?

A common working figure for low-voltage machines is at least 1 MΩ, but trends over time and manufacturer values matter more than one reading.

MAR-239 · Why are high voltage systems used on large ships?

For the same power, higher voltage reduces current, so cable size, losses and fault current drop. It is common where generator capacity is very large, such as cruise ships and LNG carriers.

MAR-240 · What is the purpose of the generator's alternator space heater?

It keeps windings warm and dry when the machine is idle, preventing condensation and loss of insulation resistance.

Refrigeration & AC on Ships

MAR-241 · What is superheat and why is it controlled?

Superheat is the temperature of the vapour above its saturation temperature at evaporator outlet. Keeping a few kelvin of superheat ensures no liquid reaches the compressor while using most of the evaporator.

MAR-242 · What is subcooling?

Cooling the liquid refrigerant below its condensing temperature. It increases refrigeration effect per kg and prevents flash gas before the expansion valve.

MAR-243 · What are the signs of refrigerant undercharge?

Low suction pressure, high superheat, bubbles in the sight glass, long running time and poor cooling.

MAR-244 · What causes high discharge pressure?

Poor condenser cooling (fouled tubes, low seawater flow), air or non-condensables in the system, or overcharge.

MAR-245 · How is air removed from a refrigeration system?

Air collects at the top of the condenser and is purged there with the compressor stopped and condenser cooling running, or recovered through a purge unit.

MAR-246 · What is pump-down?

Closing the liquid line valve and running the compressor to move the refrigerant into the condenser and receiver, so the low side can be opened for maintenance.

MAR-247 · Why is liquid slugging dangerous for compressors?

Liquid is incompressible and can break valves, pistons or connecting rods. It is caused by low superheat, a stuck-open expansion valve or flooded evaporator.

MAR-248 · How does the air conditioning plant control humidity?

In summer, air is cooled below its dew point over the cooling coil to condense moisture, then reheated if needed. In winter, steam or water spray adds humidity.

MAR-249 · What is a reefer container and how is it powered?

A refrigerated container with its own refrigeration unit, connected to the ship's electrical supply through reefer sockets. Large reefer loads must be included in the electrical load analysis.

MAR-250 · What is the oil separator in a refrigeration plant?

A vessel after the compressor that removes lubricating oil from the discharge gas and returns it to the crankcase, keeping oil out of the heat exchangers.

MAR-251 · Why is R22 being phased out?

R22 is an HCFC that depletes the ozone layer. Under the Montreal Protocol and MARPOL Annex VI, new installations with ozone-depleting substances are prohibited.

MAR-252 · What is the crankcase heater on a refrigeration compressor?

It keeps the oil warm during standstill so refrigerant does not dissolve in the oil. This prevents oil foaming and poor lubrication at start.

Fuels, Lubrication & Bunkering

MAR-253 · What is the injection viscosity for HFO and how is it achieved?

Typically about 10–15 cSt at the injectors. HFO is heated, often to around 120–150 °C, and a viscosity controller adjusts steam to the heater.

MAR-254 · What is the CCAI?

The Calculated Carbon Aromaticity Index, worked out from density and viscosity. It indicates ignition quality of residual fuel, and higher values mean longer ignition delay.

MAR-255 · What are cat fines and why are they harmful?

Catalytic fines are hard aluminium and silicon particles left from refinery cracking. They cause severe abrasive wear of liners, rings and fuel pumps, so purification must remove them.

MAR-256 · What are the main bunkering precautions?

Agree quantities and pumping rates, check tank soundings and ullages, plug scuppers, keep SOPEP equipment ready, maintain communication with the barge, take representative samples, and monitor tanks to avoid overflow.

MAR-257 · How are bunker samples taken and kept?

A continuous drip sampler at the ship's manifold collects a representative sample throughout delivery. The MARPOL sample is sealed, signed and retained for at least 12 months.

MAR-258 · Why is new bunker fuel not mixed with old fuel in the same tank?

Fuels may be incompatible, causing asphaltenes to precipitate as sludge that blocks filters and purifiers. New fuel should go into empty tanks where possible.

MAR-259 · What is fuel changeover before entering an ECA?

Switching from high-sulphur or VLSFO to compliant 0.10% S fuel early enough to flush the system. The time, position and tank volumes must be logged.

MAR-260 · Why is the changeover from HFO to MGO done gradually?

To avoid thermal shock in fuel pumps that could cause plunger seizure, and to keep viscosity above the minimum. The temperature change rate is limited, often to about 2 °C per minute.

MAR-261 · What lube oil tests are done on board?

Viscosity, water content, TBN, flash point (for fuel dilution) and appearance or spot tests. Shore labs check wear metals and contaminants.

MAR-262 · Why must cylinder oil BN match fuel sulphur?

Too low a BN for the fuel sulphur lets acid cause cold corrosion. Too high a BN for low-sulphur fuel leaves calcium deposits that polish the liner and cause scuffing.

MAR-263 · How is bunker quantity calculated?

Measure tank soundings, find volume from tank tables, correct to 15 °C with the volume correction factor, and multiply by density at 15 °C: mass = V₁₅ × ρ₁₅.

MAR-264 · What is the purpose of fuel homogenisers?

They break up water droplets and sludge particles in fuel into a fine stable emulsion, improving combustion and reducing purifier sludge.

Maritime Regulations (SOLAS, MARPOL, STCW, ISM, ISPS)

MAR-265 · What are the six annexes of MARPOL?

Annex I: oil. Annex II: noxious liquid substances in bulk. Annex III: harmful substances in packaged form. Annex IV: sewage. Annex V: garbage. Annex VI: air pollution and energy efficiency.

MAR-266 · What are the MARPOL Annex I limits for machinery space bilge discharge?

The ship must be en route, the effluent must be processed through approved oil filtering equipment, and its oil content must not exceed 15 ppm. Discharge is not allowed in special areas except under specific conditions.

MAR-267 · What are the STCW rest hour rules?

At least 10 hours of rest in any 24 hours and 77 hours in any 7 days. Rest may be divided into no more than two periods, one of at least 6 hours, and intervals between rest periods must not exceed 14 hours.

MAR-268 · What is the Designated Person Ashore (DPA)?

A person in the company with direct access to top management who monitors safety and pollution prevention and serves as the link between ship and shore under the ISM Code.

MAR-269 · What certificates show ISM compliance?

The Document of Compliance (DOC) for the company and the Safety Management Certificate (SMC) for each ship.

MAR-270 · What are the three ISPS security levels?

Level 1: normal, with minimum protective measures. Level 2: heightened risk with extra measures. Level 3: exceptional, when a security incident is probable or imminent.

MAR-271 · Who are the SSO, CSO and PFSO?

The Ship Security Officer runs the ship security plan on board. The Company Security Officer is responsible ashore for the company's ships. The Port Facility Security Officer is responsible for the port facility.

MAR-272 · What is the SOPEP?

The Shipboard Oil Pollution Emergency Plan required by MARPOL Annex I. It gives procedures and contacts for reporting and responding to oil spills.

MAR-273 · What does MARPOL Annex VI regulate?

Emissions of SOx, NOx, ozone-depleting substances, VOCs and shipboard incineration, plus energy efficiency rules such as EEDI, EEXI, SEEMP and CII.

MAR-274 · What are the NOx Tier limits?

Tier I, II and III set progressively lower NOx limits depending on engine rated speed and build date. Tier III applies in NOx Emission Control Areas for engines on newer ships and needs SCR, EGR or gas engines.

MAR-275 · What does MARPOL Annex V say about garbage?

Discharge of plastics is banned everywhere. Other garbage like food waste is allowed only at set distances from land, and ships must keep a garbage management plan and Garbage Record Book.

MAR-276 · What is the Continuous Synopsis Record (CSR)?

A SOLAS document recording the ship's history: name, flag, owner, managers, class society and registration changes.

Safety, Firefighting & Survival

MAR-277 · How does a CO₂ flooding system put out a fire?

CO₂ displaces oxygen in the protected space below the level needed for combustion. For machinery spaces, the FSS Code requires 85% of the gas to be discharged within 2 minutes.

MAR-278 · What precautions are taken before releasing CO₂ in the engine room?

Muster and account for all personnel, close ventilation, fire dampers, doors and skylights, stop fuel pumps and fans by remote stops, and only then release the gas on the Master's order.

MAR-279 · Why is the engine room not re-entered soon after CO₂ release?

The space is oxygen-deficient, and early re-entry can let air in and reignite hot surfaces. Boundary cooling continues and the space is ventilated and gas-tested before entry.

MAR-280 · What is enclosed space entry procedure?

Risk assessment, permit to work, isolation, thorough ventilation, gas testing for oxygen, flammables and toxics, a standby person at the entrance, communication, and rescue equipment ready.

MAR-281 · What atmosphere is required for enclosed space entry?

Oxygen about 21% by volume, flammable gas below 1% of LFL, and toxic gases below their occupational exposure limits, verified by calibrated instruments.

MAR-282 · What is boundary cooling?

Spraying water on bulkheads and decks next to a fire to stop heat spreading by conduction into adjacent spaces.

MAR-283 · What is the function of the emergency fire pump?

It is located outside the machinery space with independent power and suction. It supplies the fire main if the engine room is lost to fire.

MAR-284 · What drills are required on cargo ships?

Abandon ship and fire drills at least monthly for each crew member, plus enclosed space entry and rescue drills at least every two months, among others.

MAR-285 · What is a hydrostatic release unit (HRU)?

A device that frees the liferaft at a set water depth (a few metres) as the ship sinks, so the raft floats up and inflates.

MAR-286 · Why should water not be used on an oil fire?

Water sinks below the burning oil, flashes to steam and spreads the burning oil. Foam, dry powder or CO₂ are used instead, though water fog can cool.

MAR-287 · What is a fire damper?

A shutter in a ventilation duct that closes to stop smoke and fire spreading through ducting.

MAR-288 · What is a quick-closing valve?

A valve on fuel and lube oil tank outlets in machinery spaces that can be closed remotely from outside the space in a fire.

Engine Room Operations & Watchkeeping

MAR-289 · What should be checked when taking over an engine room watch?

Standing and special orders, machinery state, alarms, tank levels, bilge levels, any ongoing work or isolated equipment, fuel and lube status, and the logbook. The relieving engineer must be fit and adjusted to conditions.

MAR-290 · What are the steps to prepare the main engine for departure?

Warm up jacket water, start lube oil, cooling and fuel pumps, check levels, drain air bottles, blow through the engine with indicator cocks open, test steering gear, try ahead and astern on fuel, and synchronise clocks with the bridge.

MAR-291 · Why is the engine blown through before starting?

Turning the engine on air with the indicator cocks open expels any water, oil or fuel that has collected in the cylinders, preventing hydraulic lock.

MAR-292 · What is done after "finished with engines"?

Stop the engine, keep lube and cooling pumps running until temperatures fall, close starting air, engage turning gear if needed, and change over to harbour generators and services.

MAR-293 · What should the duty engineer do on a blackout?

Inform the bridge, confirm the emergency generator is supplying, find the cause, restart and connect a main generator, then restart essential auxiliaries in sequence before propulsion.

MAR-294 · When must the Chief Engineer be called?

When there is damage or malfunction of machinery that threatens safe operation, fire, flooding, loss of power, unusual noises or readings, or as written in the standing orders.

MAR-295 · What are the duties during manoeuvring?

The engine room must be manned, standby generators running, engine orders executed promptly and recorded in the movement book, and the bridge told of any problem.

MAR-296 · How is the bilge system operated safely?

Bilges are pumped to the bilge holding tank and processed through the OWS. All discharges and transfers are recorded in the Oil Record Book, and the overboard valve is never bypassed.

MAR-297 · What is the UMS checklist before leaving the engine room unattended?

Confirm all alarms tested and on, tanks topped up, standby pumps on auto, fire detection active, bilges dry, no unusual leaks, and duty alarm transferred to the bridge and duty engineer.

MAR-298 · Why are running hours recorded?

They schedule maintenance in the PMS, monitor equipment usage and support class surveys such as continuous machinery survey.

MAR-299 · How is a fuel oil leak in the engine room handled?

Stop or isolate the source, contain and clean the spill, keep it away from hot surfaces, and inform the Chief Engineer. Spray shields and jacketed high-pressure pipes reduce this risk.

MAR-300 · What is the purpose of the engine movement (bell) book?

It records every engine order from the bridge with time, for use in incident investigations and verifying response to orders.

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