Extended Operational and Trade Vocabulary

Engine Room Watchkeeping and UMS Operations glossary

The engine-room watchkeeping and unattended-machinery-space vocabulary: the ABS automation notations (ACCU, ACC), AC distribution at 440 V 60 Hz, hydraulic accumulators, acoustic enclosures, and the alarm, monitoring, and control systems that permit UMS operation. Grounds each term in the watch routine and the automation standard it depends on.

638 defined terms.

Showing 250 on this page (page 1 of 3).

A

ABS ACC: ABS notation for centralized control of propulsion machinery from a continually manned control station.
ABS ACCU: ABS notation for automatic control of machinery in unattended centralized control, periodically unattended machinery space.
AC: Alternating current, the standard distribution form for ship low voltage systems at 440 V 60 Hz or 400 V 50 Hz.
Accumulator: Pressure vessel storing hydraulic oil under nitrogen precharge, used in steering gear and fuel injection systems.
Acoustic enclosure: Sound attenuating housing fitted around generator engines and purifiers to limit ECR noise exposure.
Active redundancy: Configuration where two or more units share load so that failure of one does not interrupt service.
Actuator: Pneumatic, hydraulic, or electric device that positions a valve or damper on command from the control system.
AE: Auxiliary engine, the medium speed diesel driving a ship's electrical generator.
Aft peak tank: Aftermost ballast tank around the sterntube.
After cooler: Air cooler downstream of turbocharger compressor, lowering scavenge air temperature before the receiver.
Air bottle: Starting air receiver, typically two of 30 bar working pressure for main engine and one for auxiliaries.
Air cooler cleaning: Periodic chemical or mechanical cleaning of scavenge air cooler to restore charge air pressure.
Air dryer: Refrigerant or desiccant unit removing moisture from control air to prevent valve sticking.
Air run: Turning the main engine on starting air with indicator cocks open, performed before standby.
Alarm acknowledge: Operator action silencing the audible signal while the visual indication remains until the cause is cleared.
Alarm group: Logical grouping of alarms by system, used for ECR mimic and bridge repeater displays.
Alarm printer: Hard copy printer logging every alarm event with date and time stamp, required under IACS UR M35.
Alfa Laval MAB: Manual sludge discharge purifier series for fuel and lube oil cleaning on older tonnage.
Alfa Laval MOPX: Self cleaning paring disc purifier widely fitted for HFO and lube oil treatment.
Alfa Laval PureBilge: Centrifugal oily water separator certified to MEPC.107(49) 15 ppm.
Alfa Laval S separator: Modern hermetic centrifugal separator using EPC 60 control for fuel and lube oil cleaning.
Ammonia refrigeration: R717 system used on reefer carriers, requiring detection and ventilation precautions.
Anchor watch: Watch maintained on anchored vessel.
Annunciator: Panel of indicator lamps and audible signal alerting watchkeeper to abnormal conditions.
Anti-rolling tank: Passive or active U-tube for roll damping (Frahm tank).
API Gravity: American Petroleum Institute density scale; higher API = lighter crude.
Astern guardian valve: Valve in maneuvering system preventing astern starting air admission when ahead direction is selected.
Atmospheric drain tank: Vented tank receiving steam condensate at atmospheric pressure for return to the feed system.
Auto changeover: Automatic transfer between duty and standby pumps on low pressure or running signal failure.
AutoChief: Kongsberg main engine remote control and safety system, current generation AutoChief 600.
Auxiliary blower: Electrically driven blower for two-stroke engine starting and low load.
Auxiliary boiler: Oil-fired boiler for steam at sea when waste-heat is insufficient.
Availability: Fraction of operating time a machinery item is ready to perform its function.

B

Babbitt: Tin or lead based white metal lining used in main bearings and crosshead bearings.
Back pressure: Exhaust system pressure at engine outlet, monitored to detect economizer or silencer fouling.
Balanced draft: Combustion air system where forced and induced draft fans maintain furnace near atmospheric pressure.
Ballast pump: Centrifugal or self priming pump moving ballast water, increasingly replaced by submersible types.
Barred speed range: Engine speed band of forbidden continuous operation due to torsional resonance, displayed on the tachometer.
Base oil: Mineral or synthetic stock from which lubricants are formulated.
Battery limit: Boundary line between two systems used to delineate maintenance responsibility.
BDC: Bottom dead center, lowest piston position used as reference for indicator diagrams.
Bedplate: Steel base on a tank container frame supporting the pressure vessel.
Bell book: Engine room log of telegraph orders received and acknowledged during maneuvering.
Bilge alarm: 15 ppm oily water discharge monitor.
Bilge Holding Tank: Tank for collected bilge water; sounded and inspected for MARPOL compliance.
Bilge keel: Longitudinal fin on the turn of bilge to damp roll motion.
Bilge well: Recess at low point of engine room floor collecting drainage to the bilge system.
Black out: Total loss of ship electrical power, triggering emergency generator start under SOLAS II-1/43.
Black start: Restoration of main switchboard from emergency generator after a blackout.
Blow by: Combustion gas leakage past piston rings into the crankcase, detected by oil mist or pressure rise.
Blow down valve: Boiler valve discharging concentrated water to control total dissolved solids.
Blue smoke: Exhaust indication of lube oil burning, often from worn rings or valve stems.
BN: Base number of lube oil expressed in mg KOH per gram, monitored by drip test or laboratory.
Boil off gas: Vaporized cargo from LNG tanks used as fuel in ME-GI or DFDE plants.
Boiler gauge glass: Bi color or reflex sight glass showing drum water level, blown down each watch.
Boiler safety valve: PSV per ASME Section I or class rules.
Booster module: Skid combining fuel pumps, heaters, filters, and viscometer supplying main engine at injection pressure.
Booster pump: Pump raising fuel system pressure ahead of supply or circulation pumps.
Bow thruster: Transverse-tunnel thruster forward for low-speed maneuvering.
Branch starter: Motor starter cubicle on a section board feeding an individual pump or fan.
Bridge control: Direct main engine control from the wheelhouse, normal mode at sea on most ships.
Bridge watch alarm: BNWAS, SOLAS V/19, separate from the engineers' alarm but architecturally similar.
Bridge wing telegraph: Repeater unit on each bridge wing allowing ordering from there during berthing.
Brown smoke: Indication of incomplete combustion from low compression or fuel injector defect.
Bunker delivery note: BDN, document required under MARPOL Annex VI Regulation 18 listing fuel quantity and sulphur content.
Bunker sample: MARPOL sample sealed at the manifold during bunkering, retained for 12 months.
Burner management system: BMS, sequence and safety logic for boiler firing including purge and flame supervision.
Bus tie breaker: Switchboard breaker connecting two sections of the main bus, normally closed at sea.
Butterfly valve: Disc type valve common on sea water and ventilation lines, operated by lever or actuator.
Bypass valve: Valve diverting flow around a cooler, filter, or pump for control or maintenance.

C

Caliper: Vernier or digital instrument used in PMS overhauls to measure clearances and wear.
Calorifier: Steam or electric heated vessel producing domestic hot water from fresh water.
Cam follower: Roller bearing surface tracking the cam profile to actuate fuel pump or exhaust valve.
Camshaft: Shaft carrying fuel and exhaust cams on conventional engines, replaced by electronic control in ME and RT-flex.
Cardan shaft: Universal jointed shaft transmitting torque between misaligned components such as shaft generator drives.
Cargo Pump Room: Compartment for cargo pumps on tankers; gas-hazardous zone.
Caterpillar 3500 series: Medium-speed marine diesel family.
Caterpillar C32: High speed marine diesel generator engine common on offshore vessels.
Caterpillar MaK M32C: Medium speed four stroke engine for propulsion and auxiliary service.
Caterpillar MaK M43C: 43 cm bore medium speed engine widely fitted on car carriers and reefer ships.
Caterpillar MaK M46DF: Dual fuel version of the M46 platform burning LNG or MGO.
CBT: Clean ballast tank arrangement on older tankers, with associated stripping pumps.
CCAI: Calculated carbon aromaticity index of residual fuel, derived from density and viscosity.
Centralised cooling: System using sea water only in central cooler, with freshwater serving all engine room consumers.
Centrifugal pump: Rotodynamic pump with impeller, used for sea water, ballast, fire, and bilge service.
Chain block: Manual lifting tackle used for cylinder head and bearing overhauls.
Chain drive: Roller chain transmitting motion from crankshaft to camshaft on mechanical two stroke engines.
Chief Engineer: Senior engineer in charge of machinery.
Chilled water plant: Refrigeration system producing chilled water for HVAC fan coils.
Circulating pump: Pump maintaining flow through cooling or fuel circuits during continuous operation.
Class Notation: Class society designation reflecting compliance with construction and equipment rules incorporated into SOLAS by reference.
Closed bunkering: Bunkering procedure with vapor return preventing emission to atmosphere.
CMS: Continuous machinery survey, alternative class survey regime.
Cofferdam: Temporary watertight enclosure for construction.
Cold start: Engine start from ambient temperature, requiring preheating of LO and JW on most modern engines.
Combustion chamber: Volume above piston at TDC where fuel injection and combustion occur.
Common rail: shared apron rail used by adjacent STS cranes.
Compensator: Bellows piece absorbing thermal expansion in exhaust and steam piping.
Compressed air receiver: Pressure vessel storing compressed air for starting, control, and service use.
Condensate pump: Pump returning condensate from observation tank or hotwell to feed system.
Condition based maintenance: CBM, intervention triggered by measured parameter trend rather than running hours.
Conradson carbon: Residue test on fuel oil indicating coking tendency, reported on bunker analysis.
Constant pressure turbocharging: System where all cylinders discharge into a common exhaust receiver feeding the turbocharger.
Control air: Compressed air at 7 bar supplying pneumatic instruments and valve actuators.
Cooling water expansion tank: High mounted tank accommodating thermal expansion of freshwater cooling system.
COW system: Crude oil washing arrangement on tankers using cargo as washing medium, MARPOL Annex I Regulation 33.
Crankcase explosion: Ignition of oil mist in the crankcase, mitigated by oil mist detection and explosion relief doors.
Crankcase relief valve: Spring loaded door releasing overpressure and flame trap closing thereafter.
Crankshaft deflection: Web-deflection measurement indicating alignment.
Critical alarm: Alarm requiring immediate action, displayed with highest priority on ECR and bridge.
Crosshead: Sliding bearing between piston rod and connecting rod in two stroke engines, isolating combustion from crankcase.
CSE: Continuous service equipment, machinery in continuous use on UMS ships.
Cylinder lubricator: Mechanical or electronic device dosing cylinder oil through quills into the liner.
Cylinder oil: High-BN lubricant feeding the cylinder liners of two-stroke crosshead engines.

D

Daily round: Mandatory inspection by the duty engineer of all machinery spaces under the UMS regime.
Daily tank: Service tank holding 8 to 24 hours of clean fuel for engines.
Damaged stability: Stability assessment after compartment flooding per SOLAS Ch. II-1.
Damper: Adjustable plate controlling ventilation or exhaust flow.
DC link: Direct current bus in frequency converters used for shaft generators and pod drives.
De-aerator: Vessel removing dissolved oxygen from boiler feed water.
Dead man alarm: ECR system detecting engineer movement during unattended operation, alarms ECR then bridge if not reset.
Dead man switch: Push reset button at machinery space control points satisfying the dead man timer.
Dead ship condition: SOLAS II-1/3-1.3 condition where main and auxiliary machinery is dead, requiring autonomous restoration.
Dead slow ahead: Lowest ordered speed on the engine telegraph, near minimum sustained engine rpm.
Dead watch: Colloquial term for the 00 to 04 watch, kept by the second engineer in the conventional rotation.
Delivered power: PD, propeller shaft power delivered to the propeller hub.
Demand pump: Pump starting automatically on pressure drop in hydrophore or fuel system.
Demineralizer: Water treatment unit removing dissolved salts for boiler makeup.
Density: cargo mass per unit volume, governs stowage factor.
DG: Dangerous goods.
Diagnostic: System self test feature in ECMS and PMS reporting status of inputs and outputs.
Differential pressure: dP, monitored across filters and coolers to indicate fouling.
Direct coupled: Generator or pump driven without gearing.
Dirty oil tank: Tank receiving sludge and dirty oil from engine spaces, separate from sludge tank.
DNV E0: Det Norske Veritas notation for unattended machinery space, equivalent to historic UMS.
DNV ECO: Notation for vessels with documented energy efficiency improvements.
Door switch: ECR door contact integrating with the dead man alarm system.
Double-bottom: Structural arrangement providing tanks below cargo holds.
Drain pocket: Low point in piping with a drain valve for water removal.
Drip tray: Containment beneath manifold connections to catch spills during bunkering.
Dry exhaust: Engine exhaust arrangement without water injection, used on most marine diesels.
Dual-fuel engine: Engine running on both liquid and gaseous fuels (e.g., WinGD X-DF).
Dump cooler: Cooler dissipating excess heat from freshwater system when waste heat recovery exceeds demand.
Duty engineer: Officer holding the engineering watch or, in UMS mode, on call during the night.

E

EAS: Engineers' Alarm System extending unacknowledged alarms to engineer cabins under SOLAS II-1/51.
ECC: Engine control console.
ECMS: Engine control and monitoring system.
ECO mode: Operational setting prioritizing fuel efficiency on the engine control system.
ECR: Engine control room, sound attenuated space from which UMS machinery is supervised.
Eductor: Jet pump using motive water to draw bilge or stripping suction by venturi effect.
EEDI: Energy Efficiency Design Index, MARPOL Annex VI Chapter 4.
EEXI: Energy Efficiency Existing Ship Index, MARPOL Annex VI Chapter 4.
EIAPP: Engine International Air Pollution Prevention certificate issued under MARPOL Annex VI Regulation 13.
Electric driven cargo pump: Frequency controlled motor driving cargo pump on tankers and gas carriers.
Electrical officer: ETO, watchkeeping or day work officer responsible for electrical equipment.
Electronic governor: Microprocessor based speed governor superseding mechanical Woodward UG types.
Emergency air compressor: Independent compressor capable of charging the air bottle from dead ship condition.
Emergency fire pump: Independent fire pump per SOLAS Reg. II-2/10.
Emergency generator: Self contained generator above main deck supplying essential services on blackout.
Emergency stop: Hard wired pushbutton tripping engine or pump from local and remote stations.
Engine room log book: Statutory record of engineering events, parameters, and maintenance.
Engine room round: Inspection circuit covering all machinery spaces during a UMS watch.
Engineer of the watch: STCW Chapter VIII designated officer in charge of the engineering watch.
Engineer's alarm: Loud audible signal from ECR alerting on call engineer in cabin to attend.
EOOW: Engineer officer of the watch.
Evaporator: Fresh water generator using waste heat from jacket water at low vacuum.
Exhaust gas boiler: Economizer recovering main engine exhaust heat to produce steam.
Exhaust gas deviation: Temperature spread across cylinders, monitored as combustion quality indicator.
Exhaust valve: Hydraulically actuated valve on two stroke engines, also called Burmeister valve.
Expansion tank: Header tank for cooling system.
Explosion relief door: Spring loaded door on engine crankcase or scavenge space relieving deflagration pressure.

F

Fail-Safe: Design principle ensuring failure of one element does not cause progressive collapse.
Feed pump: Boiler feed pump delivering water from hotwell to the boiler drum.
Feed water tank: Atmospheric tank storing treated water for boiler makeup.
Fifth engineer: Junior engineering officer assisting on watch where the engine room is manned.
Filter monitor: dP transmitter indicating filter element fouling on fuel and lube oil lines.
Fine filter: Final filter ahead of injectors typically rated 6 to 10 micron absolute.
Fire damper: Closure in ventilation duct sealed remotely on fire to isolate the engine room.
Fire detection system: Addressable fire alarm panel, SOLAS II-2 mandatory in machinery spaces.
First aid kit: Required at ECR, workshop, and steering gear under MLC 2006.
First engineer: Synonym for second engineer in some flag administrations.
Fixed CO2 system: Total flooding installation under SOLAS II-2 Regulation 10 for machinery spaces.
Flame arrester: Mesh element preventing flame propagation, fitted on cargo and bunker tank vents.
Flash point: Lowest temperature at which fuel vapor ignites with a pilot flame; minimum 60 C for SOLAS marine fuels (Pensky-Martens closed cup, ISO 2719).
Floor plate: Removable steel plate forming engine room flooring above bilge level.
Foam fire system: Fixed system for purifier rooms and cargo decks discharging AFFF or high expansion foam.
Forced draft fan: Combustion air blower supplying boiler furnace.
Forward bridge alarm: Engineers' alarm repeater on the bridge.
Four-stroke engine: Otto/Diesel cycle engine with separate intake, compression, power, exhaust strokes.
Fourth engineer: Junior engineer holding the 12 to 04 and 12 to 16 watch in the four engineer rotation.
Free standing console: ECR console housing PLCs, alarm system, and operator stations.
Frequency converter: Power electronic equipment converting AC to AC at variable frequency for shaft generators and motor drives.
Fresh water generator: FWG, plate or shell type evaporator producing distilled water under vacuum.
FRP grating: Fiber reinforced plastic walkway grating used in cargo pump rooms and exposed areas.
Fuel changeover: Switching from HFO to compliant fuel before entering ECA, recorded in the Oil Record Book and changeover log.
Fuel changeover log: Record required under MARPOL Annex VI Regulation 14 documenting time, position, and tank quantities.
Fuel injector: Spring or hydraulically loaded valve atomizing fuel into the combustion chamber.
Fuel oil booster module: Skid raising HFO pressure and temperature to injection conditions.
Fuel oil heater: Steam or electric heater raising HFO to the temperature for the specified viscosity.
Fuel oil service pump: Pump delivering fuel from service tank to booster module.
Fuel oil transfer pump: Screw or gear pump moving fuel between storage and settling tanks.
Fuel valve cooling: Separate diesel oil circuit cooling injector valves on engines without integrated cooling.

G

Galley extract: Ventilation duct removing cooking fumes through a grease filter and fire damper.
Gas detection: Fixed or portable detectors for hydrocarbons, oxygen, hydrogen sulphide, and CO in machinery and cargo spaces.
Gas-free certificate: Certificate before hot work in tanks.
Gauge board: Local instrument panel grouping pressure and temperature gauges for an engine or system.
Gear pump: Positive displacement pump using meshing gears, used for lube oil and fuel transfer.
Generator engine: Auxiliary engine driving the alternator.
Generator protection relay: Multifunction relay with reverse power, overload, and earth fault functions per IACS UR E16.
Globe valve: Throttling valve with disc on stem, used for steam and high pressure water service.
Governor: Speed control device, mechanical Woodward UG or electronic GAC and Heinzmann types.
Grease cup: Manually operated lubrication fitting on pumps and motors.
Green water: Solid water on deck, considered when planning weather routing from ECR aware bridge teams.
Grey water: Drainage from sinks, showers, and galley, segregated from sewage on most ships.
Gross calorific value: Higher heating value of fuel, used in heat balance calculations.
Group starter: Switchboard cubicle feeding a related group of consumers such as engine room fans.
Guide rail: Plate strip supporting crosshead shoe travel in two stroke engines.
Gust load: Transient torque on the shaft from heavy weather, monitored by torsion meter.

H

Hand priming pump: Manual pump fitted on lube oil and fuel systems for initial priming.
Harbor watch: Reduced engineering watch maintained in port with cargo and auxiliary loads active.
Heat exchanger: Plate or tube device transferring heat between two fluids without mixing.
Heater: Steam, thermal oil, or electric unit raising fluid temperature, used on fuel and tank heating.
HFO: Heavy fuel oil, residual marine fuel grade per ISO 8217 RMG and RMK.
HFO transfer log: Internal fuel movement record cross referenced with the Oil Record Book Part I.
Hi mom switch: Stick switch on manoeuvering platform for emergency stop on some MAN B&W layouts.
High level alarm: Tank level alarm preventing overflow, with separate high high overfill alarm on bunker tanks.
High suction: Upper bilge or tank suction used when low suction is fouled.
Holding tank: shoreside tank for sewage or ballast reception.
Holland Roer: Common spelling reference for steering rudder mountings in classification surveys.
Hot exhaust shielding: Insulated lagging on exhaust components above 220 deg C per SOLAS II-2/4.
Hotwell: Open tank receiving condensate and supplying feed pump suction.
Hub strake: Internal hub liner on controllable pitch propellers, not a watchkeeping item but referenced in shaft surveys.
Hydraulic clutch: Coupling between engine and shaft generator allowing PTO engagement at sea.
Hydraulic power pack: Self contained pumps, tank, and accumulator unit serving steering gear or cargo system.
Hydraulic Test: Pressure test using water to verify tank or pipe integrity.
Hydrophore: Pressurized tank with air cushion supplying domestic fresh and salt water.

I

IACS: International Association of Classification Societies, 12 members.
IACS UR M35: Unified Requirement specifying alarm and monitoring systems for periodically unattended machinery spaces.
IACS UR M36: Unified Requirement on safety systems for periodically unattended machinery spaces.
IACS UR M40: Unified Requirement on automatic and remote control of generator engines.
IACS UR M68: Unified Requirement on dimensioning and arrangement of starting air systems.
IBC Code: International Code for the Construction and Equipment of Ships Carrying Dangerous Chemicals in Bulk.
ICMS: Integrated control and monitoring system, single platform for propulsion, power, and auxiliary control.
IGS: Inert gas system on oil and chemical tankers per SOLAS II-2 Regulation 4.5 and IBC.
Imo three screw pump: Trade reference to triple screw lube oil pumps manufactured by Imo Pump.
Inboard sea chest: Sea water inlet cofferdam with strainer, isolation valve, and steam blow.
Incinerator: Onboard waste burner certified to MEPC.244(66) Standard Specification.
Indicator cock: Cylinder cock used for blowing through and connecting indicator instrument.
Indicator diagram: Pressure crank angle trace from peak pressure indicator used to assess cylinder condition.
Inert gas blower: Flue or generator gas blower delivering inert gas to cargo tanks.