Maritime English
Maritime English Glossary
647 professional maritime english terms with definitions, pronunciation and examples. Learn what each term means — free with Termify.
A
- What is Abandon Ship? A formal command given by the Master ordering crew and passengers to evacuate the vessel immediately due to grave danger...
- What is Abandon Ship Drill? A mandatory exercise in which crew and passengers practice procedures for safely abandoning the vessel and boarding life...
- What is Acknowledge Distress? Formal confirmation of receipt of a distress message, typically using prescribed wording as per SMCP and ITU RR.
- What is Acknowledge Message? Formal confirmation of receipt of a transmitted communication, usually by repeating essential content.
- What is Acknowledge Position? Instruction to confirm that a vessel’s reported navigational position has been received and understood.
- What is Acoustic Doppler Measurement? A navigational process using Doppler sonar to measure vessel speed and direction relative to water, crucial for precise ...
- What is Advance Distance Calculation? Determination of the longitudinal distance the vessel travels on the original heading during a turn from rudder order un...
- What is Advance Transfer Table? A manoeuvring aid providing predicted advance (distance along original track) and transfer (lateral distance) for specif...
- What is Advise Intentions? Request for a vessel to state its planned manoeuvre, course, or operational actions to aid traffic coordination.
- What is Advise Pilot? Request for instructions, information, or confirmation from the maritime pilot regarding navigation or maneuvers.
- What is Advise Traffic? Request for current information about vessel traffic, movement, or congestion in a specific area.
- What is Air Draft Clearance? The vertical distance from the waterline to the highest point of the vessel, used to determine safe passage under bridge...
- What is All Stations? Universal radio call addressing every vessel or station within radio range, especially for navigational warnings or urge...
- What is Alter Course? Instruction to change the vessel’s current heading in order to avoid danger or comply with traffic management.
- What is Anchor Aweigh Confirmation? The formal notification to the bridge or engine room that the anchor is clear of the seabed and ship is free to maneuver...
- What is Anchor Heave Rate? The speed at which the anchor cable is hauled in, usually measured in meters per minute, to control anchor recovery.
- What is Anchor Walkback Control? The controlled paying out of anchor chain in reverse (walkback) under power, used for precise anchor positioning or retr...
- What is Anchoring Speed Reduction? Deliberate decrease in vessel speed to a safe limit before anchor deployment, minimizing anchor dragging and ensuring pr...
- What is Anti Fouling Inspection? Port state or class survey checking hull coating compliance with IMO AFS Convention and assessing biological growth.
- What is Approach Distance Marker? Painted, lit, or electronic reference indicating remaining longitudinal distance to berth face during final approach.
- What is Approach Track Verification? Confirmation that vessel’s intended approach line aligns with planned track and pilot’s instructions before final manoeu...
- What is Automatic Backflushing? A system that automatically reverses flow through filters or strainers to remove debris and maintain performance without...
- What is Automatic Boiler Dosing? A system that automatically injects water treatment chemicals into the boiler feedwater to control scale and corrosion, ...
- What is Automatic Power Management? A computerized system on board ships that monitors and optimizes power generation and distribution automatically, ensuri...
- What is Automatic Radar Plotting? The process by which radar targets are tracked and collision risk assessed automatically by ARPA systems, displaying rea...
- What is Automatic Release Unit? A device designed to automatically release life-saving appliances, such as liferafts, when submerged or activated by spe...
- What is Auxiliary Boiler Shutdown? The complete stopping of an auxiliary boiler on board, including secure isolation and safety checks, typically during po...
- What is Auxiliary Engine Start? The operation to start a ship’s auxiliary engine, which provides electrical power or essential services independently of...
- What is Azimuth Thruster Lock? A system state where azimuth thrusters are held in a fixed orientation to prevent movement, usually for safety during ma...
B
- What is Back Up Steering? An alternative manual or powered system used to control the ship’s rudder if primary steering gear fails.
- What is Backing Power Reserve? Remaining astern propulsion capacity beyond that required for standard manoeuvre, ensuring additional stopping margin.
- What is Ballast Exchange? The procedure of replacing ballast water taken from one area with water from another, to minimize the spread of invasive...
- What is Ballast Pump Auto? An automatic mode setting on the ballast pump, enabling the pump to start and stop based on tank level sensors or a cent...
- What is Ballast Water Exchange? Operation of replacing loaded ballast with mid-ocean water at prescribed distance from land to prevent bio-invasion, log...
- What is Bank Cushion Effect? Hydrodynamic phenomenon where water pressure between a vessel and a nearby bank creates a cushion, pushing the bow away ...
- What is Bank Suction Effect? Hydrodynamic phenomenon where a vessel navigating close to a bank experiences a suction force pulling the vessel toward ...
- What is Barometric Pressure Report? Regularly transmitted statement of current atmospheric pressure and trend for meteorological data exchange and storm tra...
- What is Barometric Tendency Report? Synoptic code group summarising rate and character of atmospheric pressure change during past three hours, broadcast in ...
- What is Bergy Bit Report? An official communication or broadcast of the sighting and position of medium-sized floating ice fragments (bergy bits),...
- What is Berth Alignment Lights? Pair or range of fixed shore lights that provide visual guidance to vessels for centreline alignment during final approa...
- What is Berth Suitability Check? A verification process to ensure the selected berth meets vessel requirements in terms of depth, length, fendering, and ...
- What is Berthing Energy Budget? The total kinetic energy allowed for a vessel to safely berth, accounting for mass, speed, and fender capacity to preven...
- What is Berthing Velocity Limit? Maximum allowable approach speed normal to berth to prevent fender overload and structural damage.
- What is Bilge Water Alarm? An alert indicating the presence of excess water in the bilge spaces, often requiring automatic or manual pumping, and i...
- What is Biofouling Management Plan? A documented system required by IMO for vessels to manage and minimize the accumulation of aquatic organisms on hulls an...
- What is Blackout Recovery Sequence? A prescribed procedure to restore shipboard power and restart essential systems after total electrical blackout, ensurin...
- What is Boiler Burner Management? The control and monitoring of burner operations on marine boilers to ensure safe and efficient ignition, combustion, and...
- What is Boiler Low Water? A hazardous boiler condition where water level falls below the minimum safe mark, risking tube overheating, boiler damag...
- What is Bollard Pull Verification? Confirmation that a tug’s certified bollard-pull matches terminal requirements before allocating towage tasks.
- What is Bottom Sampling? The process of collecting liquid samples from the bottom of a cargo tank to check for water, contaminants, or stratifica...
- What is Bow Moment Coefficient? A calculated factor describing the turning moment generated by the bow, crucial for assessing vessel manoeuvrability dur...
- What is Bow Thruster Application? Use of bow thruster to generate lateral force at bow for precise positioning or counteracting environmental forces durin...
- What is Bow Tug Position? The assigned and maintained location of a tug at the bow of a vessel to provide pushing, pulling, or steering assistance...
- What is Brash Ice Warning? Message issued by ice services or VTS indicating dangerous concentrations of brash ice likely to impede manoeuvring or c...
- What is Bridge Audio Recording? Continuous audio recording of all conversations and alarms on the bridge as mandated by SOLAS for investigation and safe...
- What is Bridge Control Mode? A mode in which the propulsion and critical machinery are operated directly from the bridge, with command transferred fr...
- What is Bridge Control Transfer? The formal procedure to transfer vessel control (steering and propulsion) between the bridge and alternative control sta...
- What is Bridge Emergency Locker? A secured storage location on the bridge containing emergency gear such as fire axes, breathing apparatus, and communica...
- What is Bridge Engine Telegraph? A signaling system between bridge and engine room, used to transmit engine speed and direction orders during ship maneuv...
- What is Bridge Fire Panel? A control panel located on the bridge showing status, zones, and alarms for the ship’s fire detection and suppression sy...
- What is Bridge Manoeuvring Notebook? A logbook kept on the bridge for recording all manoeuvring orders, engine telegraph movements, helm commands, and critic...
- What is Bridge Navigational Watch? A continuous period during which designated officers and crew maintain vigilance and operational control on the bridge t...
- What is Bridge Resource Management? The effective use and coordination of all available bridge resources—personnel, equipment, and information—to ensure saf...
- What is Bridge Standing By? Notification that the navigating bridge watch is monitoring the working channel and ready to respond immediately.
- What is Bridge Wing Clearance? Minimum air gap required between ship’s bridge wing extremities and shore structures or lock walls during manoeuvring.
- What is Broadcast Warning? A formal message disseminated by VTS, harbour authority, or vessels to alert all ships in an area about navigational haz...
- What is Buoy Unlit? A navigation buoy whose light is inoperative or not functioning, presenting a hazard at night.
- What is Busy Channel? Notification that the selected VHF working channel is congested with traffic, making immediate communication difficult.
- What is Butterworth Machine? A mechanical rotating cleaning device used for washing and gas freeing ship cargo tanks using pressurized jets of water ...
C
- What is Cancel Distress? Official transmission that a previous distress message is no longer valid, usually after the situation has been resolved...
- What is Cancel Message? Official notification that a previously transmitted message or warning is no longer valid or has been withdrawn.
- What is Cancel Warning? Official notification that a previously issued warning is no longer in effect.
- What is Cancel Warning? Formal message to withdraw or annul a previously issued navigational, meteorological, or safety warning that is no longe...
- What is Capstan Pull Capacity? Maximum continuous line-pull that a deck capstan can exert when hauling mooring lines at rated speed.
- What is Cargo Blending? The controlled mixing of different cargoes or grades in a tank to achieve a specified product quality or specification, ...
- What is Cargo Compatibility? Assessment of whether different cargoes can be safely loaded, carried, or stored together without risk of dangerous chem...
- What is Cargo Dehydration? The process of removing water from cargo, especially crude oil, by settling, heating, or chemical means, to meet quality...
- What is Cargo Dehydration? The process of removing water from cargo, especially crude oil, by settling, heating, or chemical means to meet quality ...
- What is Cargo Draining? Controlled removal of cargo residues or small remaining quantities from tanks and lines after main discharge, ensuring t...
- What is Cargo Draining? Removal of cargo residues or small quantities from tanks and pipelines after main discharge, ensuring tanks are as empty...
- What is Cargo Expansion? The increase in cargo volume due to temperature rise, requiring careful calculation and monitoring to avoid overflow or ...
- What is Cargo Heating? The controlled application of heat to cargo in tanks to maintain pumpability and product quality, especially with heavy ...
- What is Cargo Hose? A flexible hose designed for transferring liquid cargo between ship and shore, constructed and tested for strength and c...
- What is Cargo Manifold? A pipe assembly on a ship’s deck used for connecting shore hoses and controlling the transfer of liquid cargo to or from...
- What is Cargo Sampling? Procedure for collecting representative samples of cargo for quality analysis, documentation, and regulatory compliance.
- What is Cargo Sequencing? The planned order and timing for loading, transferring, or discharging cargoes in different tanks to maintain stability ...
- What is Casualty Muster? The assembly and accounting of crew and passengers following an incident to identify and assist injured or missing perso...
- What is Change Channel? Instruction to switch VHF radio communications from one designated channel to another for operational or traffic managem...
- What is Channel Cross Current? Lateral water flow across a dredged channel causing set and drift that must be compensated during navigation.
- What is Channel Design Depth? The minimum depth of a navigational channel as determined and maintained by authorities for safe passage of vessels, ref...
- What is Channel Occupied? Notification that a fairway or navigation channel is temporarily blocked or being used by another vessel, requiring othe...
- What is Channel Sixteen? The international VHF radio distress, safety, and calling channel (156.8 MHz) monitored at all times by ships and shore ...
- What is Channel Sixteen? The international VHF radio distress, safety, and calling frequency (156.8 MHz) mandatory for all seagoing vessels to mo...
- What is Check Correctness? Instruction to verify the accuracy of a reported position, course, message, or navigational information before proceedin...
- What is Check Position? Instruction or request to verify the vessel's current navigational position using all available means, including GPS, ra...
- What is Check Range? Instruction or query to verify the distance to a navigational object, other vessel, or danger, often using radar or visu...
- What is Check The Swing? Helm or mooring order to observe and, if necessary, limit or arrest the vessel's swinging motion, especially when turnin...
- What is Chemical Protective Suit? A specialized suit worn by crew for personal protection against hazardous chemicals, especially during spill or leak eme...
- What is Clear Astern Distance? The available unobstructed distance behind the vessel, critical for manoeuvring astern.
- What is Closed Breathing Apparatus? A self-contained device that provides breathable air in hazardous or smoke-filled environments, preventing the inhalatio...
- What is Closed Gauging? A method of measuring tank levels or taking samples without exposing tank contents to the atmosphere, using closed devic...
- What is Closed Loading? A cargo transfer method where tanks are loaded via closed systems to prevent vapour emissions, following ISGOTT and MARP...
- What is Closed Venting? Method of venting tank vapours through a controlled, closed system to prevent release of gases to the atmosphere, comply...
- What is Coastal Current Advisory? Official notice to mariners about significant changes, hazards, or anomalies in coastal water currents affecting safe na...
- What is Coastal Station? A shore-based VHF or radio station responsible for maritime safety and communication in a designated coastal area.
- What is Cold Front Approach? A message or forecast that a cold front is moving into the operational area, often accompanied by abrupt wind shift, fal...
- What is Cold Spell Warning? An official warning issued to inform mariners of an expected period of unusually low temperatures, which may affect vess...
- What is Collision Risk? Phrase indicating that two or more vessels are on courses or at speeds that may result in collision unless action is tak...
- What is Command Delay Compensation? Systematic adjustment made to navigation or machinery commands to account for time lag between order and vessel response...
- What is Communications Test? A check of the operational status and clarity of shipboard, shore, or VTS radio equipment by transmitting test calls and...
- What is Confirm Bearing? Instruction to verify and report the direction of an object or navigational aid from the vessel, usually in degrees rela...
- What is Confirm Course? A request or instruction to verify and state the vessel’s current or intended navigational course, usually in degrees tr...
- What is Confirm Position? Request or instruction to verify and report the current location of a vessel, typically in latitude and longitude.
- What is Conning Display Layout? The arrangement of navigation and maneuvering information shown on the conning display for optimal bridge decision-makin...
- What is Containment Boom? A floating barrier deployed to contain and control oil or chemical spills on the surface of the water.
- What is Continue Listening? Instruction to keep monitoring a specified VHF radio channel or other communication line for further traffic or safety m...
- What is Control Surface Integration? The coordinated operation of rudders, stabilisers, and other movable surfaces to achieve optimal vessel steering and sta...
- What is Controllable Pitch Propeller? A propeller with blades whose pitch can be adjusted while running, allowing for variable thrust and improved maneuverabi...
- What is Controlled Drift Angle? Intentional small leeway angle set between vessel heading and track to counter cross-wind or current during approach.
- What is Cooling Water System? The network of pipes, pumps, and heat exchangers circulating water to remove excess heat from the main engine and auxili...
- What is Coordinates Confirmed? Affirmation that the provided position or waypoint coordinates are checked and verified as correct, usually before repor...
- What is Course Alteration Point? A precisely charted position where a ship is required to change its course, usually as part of a passage plan.
- What is Course Made Good? The actual path of a vessel over the ground, as determined by position fixes, regardless of set or drift.
- What is Course Unchanged? A statement or confirmation that a vessel’s present heading will not be altered.
- What is Course Unchanged? Statement indicating that the vessel’s heading remains as previously instructed or reported.
- What is CPP Negative Pitch? A controllable pitch propeller blade setting that provides astern thrust for stopping or reversing the vessel.
- What is CPP Pitch Zero? The position of a controllable pitch propeller (CPP) where the blades are aligned to produce no thrust, used for stoppin...
- What is CPP Positive Pitch? A controllable pitch propeller blade setting that provides forward thrust, the amount adjusted for desired vessel speed ...
- What is Crankcase Explosion Relief? A safety device fitted on engine crankcases that vents pressure and flame in the event of a crankcase explosion, reducin...
- What is Crash Stop Distance? Measured distance travelled from full ahead to complete stop using maximum astern power and rudder amidships.
- What is Crew Muster? The assembly of all crew at designated muster stations for roll-call, instruction, or emergency drill, as per muster lis...
- What is Crew Survival Craft? A life-saving craft, such as a lifeboat or liferaft, carried on board and designated for the emergency evacuation and su...
- What is Critical Machinery List? An official document or database on board identifying all essential machinery whose failure would significantly affect v...
- What is Cross Track Error? The perpendicular distance between a vessel's actual position and the planned track line, used for navigation accuracy.
- What is Crude Oil Washing? The process of cleaning cargo tanks using high-pressure crude oil jets during or after discharge to reduce residual carg...
- What is Current Set Drift? The direction (set) and speed (drift) of water current affecting the ship’s course and position.
- What is Cushion Effect Estimate? An assessment of the air or water pressure that builds up between a vessel and the berth or another vessel, influencing ...
- What is Cyclone Warning? Official alert issued when a tropical cyclone with gale-force winds is expected to affect a maritime area within 24 hour...
- What is Cylinder Cut Out? A control action or device used to disable fuel supply to a cylinder, usually for maintenance or troubleshooting, while ...
- What is Cylinder Oil Feed? The controlled supply of lubricating oil to the main engine cylinder liners, essential for reducing friction and wear, a...
D
- What is Damage Assessment? A structured evaluation of damage sustained by a vessel after an incident, including extent, location, and impact on sea...
- What is Damage Control? The procedures and measures to limit, manage, or repair damage on board, especially after collision, flooding, fire, or ...
- What is Damage Control Locker? A secured storage area on board for tools, plugs, and equipment needed for rapid response to hull damage, flooding, or e...
- What is Damage Control Party? A designated team trained and tasked to control flooding, fire, or structural damage during emergencies on board.
- What is Danger Area? A specified maritime zone where navigation is hazardous due to military exercises, wrecks, shallow waters, or other dang...
- What is Danger Area? A specific zone designated as hazardous to navigation due to wrecks, shoals, operations, or other maritime risks; marine...
- What is Dangerous Cargo? Any substance or material that poses a significant risk to health, safety, or property during transport by sea, as defin...
- What is Davit Clearance Verification? Process of ensuring the davit’s operational path is free of obstruction and ready for safe lifeboat launching or recover...
- What is Dead Slow Ahead? Engine telegraph order instructing propulsion at the lowest possible speed ahead, used for delicate manoeuvring or conge...
- What is Dead Slow Astern? Engine telegraph order instructing propulsion at the lowest possible speed astern, used for delicate reversing or while ...
- What is Deaerator Tank Level? The measured height of water within the deaerator tank, critical for ensuring proper removal of dissolved gases from boi...
- What is Deep Water Route? A route within defined limits in deep water that is charted and designated for the passage of vessels requiring deep dra...
- What is Dense Fog Advisory? Warning issued when visibility expected below one-half nautical mile due to thick fog, requiring sound signals and speed...
- What is Diesel Oil Tank? A dedicated tank for storing diesel oil, used for main engines, auxiliary engines, or emergency generators on board ship...
- What is Distress Alert? An internationally recognized signal, transmitted by GMDSS or VHF, indicating grave and imminent danger requiring immedi...
- What is Distress Communication? Transmission of information regarding a distress situation, including distress calls, messages, and subsequent coordinat...
- What is Distress Communication? Radio transmission used to indicate that a vessel or person is in grave and imminent danger requiring immediate assistan...
- What is Distress Frequency? A radio frequency internationally allocated for maritime distress, safety, and calling, such as VHF channel 16 (156.8 MH...
- What is Distress Priority? The highest level of urgency assigned to radio or communication messages involving imminent danger and the need for imme...
- What is Distress Relay? The retransmission of a received distress call or message by a station not in distress, alerting other ships or coast st...
- What is Distress Signal? A recognized sound, light, radio, or visual signal sent by a vessel or person indicating imminent danger and urgent need...
- What is Distress Signal? A signal indicating a vessel or person is in grave and imminent danger and requires immediate assistance. Includes visua...
- What is Distress Traffic? Radio transmissions exclusively concerning vessels or persons in grave and imminent danger, given absolute priority on a...
- What is Docking Ramp Gradient? The measured incline of a docking ramp, influencing the safe entry, exit, and support of a vessel during docking or undo...
- What is Double Bottom Tank? A compartment at the bottom of the ship, between the inner and outer hull, used for ballast water, fuel, or as a safety ...
- What is Draft Required? Request or statement of the minimum water depth needed for safe passage of a vessel based on its loaded draft.
- What is Draft Survey? A method of determining the weight of cargo loaded or discharged by measuring the vessel’s draft marks before and after ...
- What is Drag Anchor? Situation where a vessel’s anchor does not hold, causing the ship to drift from its intended position.
- What is Drag Anchor? Situation where a vessel’s anchor fails to hold and the vessel moves from its intended position, risking collision or gr...
- What is Drift Angle Alarm? Navigation sensor alert triggered when vessel’s leeway or sideslip exceeds predefined safe threshold relative to track.
- What is Drill Completion? Formal declaration that a safety or emergency drill has been carried out as scheduled and all required actions are compl...
- What is Drill Completion? Confirmation that a safety, fire, or emergency response drill has been carried out and all required actions are complete...
- What is Drip Tray? A shallow container placed beneath piping joints or hoses to catch leaks or drips during cargo transfer operations and p...
- What is Drop Line? A flexible line or pipe used to transfer liquids vertically in a tank, commonly for sampling, loading, or discharging at...
- What is Dynamic Draught Allowance? An additional draught margin included to account for dynamic effects such as squat, trim, and vessel movement in shallow...
- What is Dynamic Positioning Hold? A control mode where a vessel maintains its heading and position automatically using thrusters and propellers, essential...
E
- What is Ease To Five? Helm order instructing the helmsman to reduce rudder angle to five degrees while maintaining course adjustment.
- What is Ebb Tide Prediction? Tabulated forecast time and rate of falling tide current used for harbour passage planning.
- What is Electric Motor Overload? A condition in which an electric motor draws current above its rated limit, risking overheating and possible failure unl...
- What is Electronic Bearing Line? A digital navigational tool on ECDIS or radar for plotting and monitoring bearings to fixed or moving targets, improving...
- What is Electronic Docking Aid? Shore-based microwave or laser sensor system providing real-time range, closing speed, and alignment data to approaching...
- What is Electronic Range Line? A digital tool on radar/ECDIS allowing navigators to set and measure a precise distance from own ship to a selected poin...
- What is Emergency Alarm? The shipwide audible and visual signal indicating a serious emergency; activates muster or evacuation as per muster list...
- What is Emergency Bilge Pump? A portable or dedicated pump used to remove water from the bilge in case of flooding or main pump failure.
- What is Emergency Bilge Suction? A designated suction line and valve in the engine room bilge system used only in emergencies to rapidly remove water fro...
- What is Emergency Control Station? A designated area from which emergency operations such as firefighting, ventilation control, and communication are coord...
- What is Emergency Descent? A rapid controlled descent initiated due to onboard emergencies such as fire or loss of cabin pressure, as per SOLAS and...
- What is Emergency Escape? A designated route or means for crew to safely evacuate from compartments, accommodation, or machinery spaces during eme...
- What is Emergency Exit? A clearly marked route or door for rapid escape from a compartment or area during emergencies.
- What is Emergency Eye Wash? A safety device providing immediate water flow for flushing eyes exposed to chemicals, smoke, or contaminants on board.
- What is Emergency Fuel Cutoff? A safety device or procedure for rapidly stopping fuel supply to machinery or tanks in case of fire or other emergencies...
- What is Emergency Generator? A dedicated generator that supplies electrical power to essential systems during main power failure, as required by SOLA...
- What is Emergency Generator Panel? The control interface for the ship's emergency generator, enabling monitoring, activation, and shutdown of emergency ele...
- What is Emergency Generator Start? The procedure to initiate the ship's emergency generator to supply critical electrical power during a main blackout or f...
- What is Emergency Lighting? Battery-backed or independent lighting automatically activated during main power failure for safe evacuation and emergen...
- What is Emergency Muster? The immediate assembly of all crew and passengers at assigned muster stations in response to an alarm or emergency situa...
- What is Emergency Navigation Light? A portable or fixed battery-powered navigation light used to maintain minimum required navigation signals in the event o...
- What is Emergency Oxygen Supply? Portable or fixed supply of medical oxygen available for emergency use by crew or passengers in case of fire, smoke or m...
- What is Emergency Position? Location reported by a vessel or person in distress, usually in latitude and longitude for rescue coordination.
- What is Emergency Position Beacon? A radio beacon, such as an EPIRB, used to transmit the position of a vessel or survivor in distress to search and rescue...
- What is Emergency Power? Alternative power source such as a generator or battery supplying essential systems during main power failure.
- What is Emergency Procedure? A set of predefined actions and communications for crew to follow in response to emergencies such as fire, collision, gr...
- What is Emergency Reporting? The formal communication and documentation of an emergency situation to the bridge, VTS, or authorities, following stand...
- What is Emergency Response? Immediate actions taken by trained crew to mitigate emergencies such as fire, flooding, collision, or medical incidents,...
- What is Emergency Scene? The specific onboard location where an emergency incident—such as fire, flooding, or injury—has occurred and emergency r...
- What is Emergency Shutdown? Immediate cessation of cargo or bunker transfer operations, activated by crew or terminal, to prevent accidents or mitig...
- What is Emergency Shutdown? Immediate cessation of shipboard machinery, system, or cargo operation due to a critical safety or environmental risk.
- What is Emergency Shutdown Switch? A manually operated control that immediately halts machinery or electrical equipment in emergencies to prevent damage, f...
- What is Emergency Steering Gear? Alternate manual or powered system used to control ship's rudder if the main steering fails.
- What is Emergency Steering Position? A designated location, often aft, equipped for manual control of the ship’s rudder if the main steering gear or control ...
- What is Emergency Steering Position? A dedicated station—usually aft in the steering gear room—used to control the ship’s steering in the event of bridge ste...
- What is Emergency Stop? An immediate shutdown of machinery or vessel propulsion, triggered by an emergency to prevent further damage or danger.
- What is Emergency Towing? The act of towing a vessel in distress or unable to maneuver using an emergency tow line or arrangement as per SOLAS req...
- What is Emergency Towing Pennant? A strong wire or rope rigged at bow or stern, readily accessible for emergency towing if the vessel becomes disabled.
- What is Emergency Traffic? Radio messages of high urgency concerning the safety of a ship, person, or environment, requiring priority over all othe...
- What is Emergency Training? Structured instruction and practice provided to crew members to ensure preparedness for handling emergencies such as fir...
- What is Emergency Transmitter? A dedicated radio device used to send automatic distress signals, such as EPIRBs or DSC-enabled VHF/MF/HF transmitters.
- What is Emergency Water Supply? Stored or alternate source of potable water kept on board for survival use in emergencies or after system failure.
- What is Emission Control Area? Designated sea region where MARPOL Annex VI limits on SOx, NOx and PM apply; requires low-sulphur fuel or equivalent aba...
- What is Energy Efficiency Index? Calculated parameter (EEXI/EEOI) expressing CO₂ emitted per transport work, mandatory under IMO MARPOL Annex VI.
- What is Engine Data Logger? A device or software system that automatically records and stores key engine parameters for performance monitoring, diag...
- What is Engine Interlock System? An automated safety mechanism that prevents certain engine operations unless predefined conditions are satisfied, protec...
- What is Engine Load Response? The manner and speed at which the main engine adapts to sudden changes in power demand, crucial for manoeuvring and heav...
- What is Engine Load Sharing? The process of distributing electrical or mechanical load evenly between two or more engines or generators operating in ...
- What is Engine Room Alarm? An audible and/or visual signal in the engine room, indicating an abnormal or hazardous condition in machinery, systems,...
- What is Engine Room Flooding? The presence or rapid ingress of water in the engine room spaces, posing a serious risk to machinery and vessel safety, ...
- What is Engine Room Isolation? The process or system of segregating the engine room from other compartments to contain hazards such as fire, flooding, ...
- What is Engine Room Ventilation? The provision and regulation of air flow to the engine room to remove heat, fumes, and ensure safe working conditions, a...
- What is Engine Room Watch? The assigned period when crew are stationed in the engine room to monitor, operate, and respond to machinery and alarms,...
- What is Engine Safety Shutdown? An automatic or manual action that stops the engine to prevent damage or hazard when critical parameters exceed safe lim...
- What is Engine Speed Setting? The selected rotational speed at which a ship’s engine is set to operate, typically determined by bridge orders for mane...
- What is Engine Telegraph Block? A failure or obstruction in the engine telegraph system, preventing bridge orders from being transmitted to the engine r...
- What is Engine Telemetry Panel? A central control panel for monitoring, displaying, and logging engine performance parameters and alarms in real-time, o...
- What is Engine Trouble? A condition in which a vessel’s propulsion machinery is malfunctioning or unreliable, possibly affecting speed and manoe...
- What is Environmental Impact Notice? Formal notification detailing projected ecological effects of vessel operations or construction works, issued for regula...
- What is Escape Chute? An emergency evacuation device, usually an inflatable or fabric tube, enabling rapid escape from high decks to safe area...
- What is Escape Hatch? A designated exit, usually watertight, providing a safe escape route from enclosed spaces in an emergency.
- What is Escape Slide? An inflatable slide fitted to the ship’s side, designed for rapid evacuation of crew and passengers directly into the se...
- What is Escort Tug Connection? The established secured line or method by which an escort tug is physically connected to a vessel, typically for control...
- What is Escort Vessel? A vessel assigned to accompany another ship for navigational assistance, safety, security, or regulatory compliance in p...
- What is ETA Confirmed? Formal confirmation that a vessel’s estimated time of arrival is correct and accepted by both reporting vessel and autho...
- What is ETA Confirmed? Affirmation that the vessel's estimated time of arrival at a specific point has been checked and is accurate based on cu...
- What is ETA Revised? Notification that a vessel’s previously declared estimated time of arrival has changed and updated information is provid...
- What is ETA Unchanged? Confirmation that the vessel’s estimated time of arrival remains as previously reported.
- What is Evacuation Alarm? A specific alarm signal used to order immediate evacuation of the vessel or designated areas due to critical emergency.
- What is Evacuation Route? A pre-designated path marked and maintained on board for safe and efficient evacuation during emergencies.
- What is Evacuation Slide? An inflatable slide or chute deployed to allow rapid evacuation of personnel from ship to liferaft or pier during emerge...
- What is Exhaust Gas Boiler? A heat recovery unit using main engine exhaust gases to generate steam for shipboard heating or auxiliary systems, integ...
- What is Exhaust Temperature Sensor? A device that measures and transmits the temperature of exhaust gases, crucial for monitoring engine performance and pre...
- What is Explosion Risk? The probability of explosion due to flammable vapours, gases, or materials present in a compartment or operational area.
- What is Explosion Risk? The immediate or potential danger of explosion caused by flammable vapours, gases, or dust in confined spaces or cargo a...
F
- What is Fairway Centreline Alignment? The practice of steering a vessel so that its longitudinal axis remains aligned with the designated navigational centrel...
- What is Fairway Turning Basin? A designated widened section of a navigational fairway, specifically constructed to allow vessels to safely turn or chan...
- What is Falling Overboard? The accidental or intentional act of a person leaving the vessel and entering the sea, triggering immediate man-overboar...
- What is Fast Ice Expansion? Rapid seaward growth of shore-fast ice, restricting manoeuvring space and increasing risk of besetment for vessels.
- What is Fender Energy Absorption? Capacity of berth fender system to absorb kinetic energy of vessel at specified berthing velocity without exceeding desi...
- What is Fender Panel Contact? The point or process where the vessel's hull makes contact with the berth fender panel, usually monitored to avoid struc...
- What is Fire Alarm? An audible and/or visual signal, automatically or manually triggered, alerting crew to the presence of fire and the need...
- What is Fire Alarm? An audible and/or visual signal system activated manually or automatically to warn crew of fire and trigger the ship’s e...
- What is Fire Blanket? A sheet made of fire-resistant material used to smother small fires by cutting off the oxygen supply, often located in g...
- What is Fire Blanket? A fire-resistant sheet used to smother small fires or protect personnel during escape, required in galley and accommodat...
- What is Fire Control Plan? A detailed, IMO-mandated shipboard diagram showing locations and procedures for firefighting equipment, escape routes, a...
- What is Fire Control Plan? A mandatory shipboard document showing fire safety systems, detection, protection, and escape routes as required by SOLA...
- What is Fire Control Station? A designated area on board equipped with firefighting equipment and control panels for managing emergency fire situation...
- What is Fire Door? A specially constructed door designed to resist fire and prevent the spread of flames and smoke between compartments or ...
- What is Fire Drill? A mandatory exercise where crew practice procedures for responding to fire emergencies, including alarms, mustering, and...
- What is Fire Locker? A designated compartment or cabinet onboard containing firefighting equipment such as hoses, nozzles, and personal prote...
- What is Fire Main? A fixed piping system on a ship delivering water under pressure for firefighting throughout the vessel.
- What is Fire Main? The principal pipeline on board supplying seawater under pressure to hydrants and hoses for firefighting, as specified b...
- What is Fire Party? A designated team trained and assigned to respond to onboard fires and operate firefighting equipment as per muster list...
- What is Fire Party? A team of designated crew members trained and equipped to respond immediately to fire alarms, undertake firefighting, an...
- What is Fire Party? A designated team of trained crew members equipped to respond immediately to fire alarms, conduct firefighting, and perf...
- What is Fire Pump? A fixed or portable pump designed to supply water to firefighting systems throughout the vessel, essential for controlli...
- What is Fire Pump? A dedicated pump used to supply seawater to fire hydrants and hoses on board for firefighting operations.
- What is Fire Suit? A specialized suit, heat-resistant and insulated, worn by crew to provide protection against fire and high temperatures ...
- What is Fire Zone? A designated compartment or section of a vessel, defined by structural boundaries, to limit fire spread and facilitate f...
- What is Fire Zone? A designated section of a ship separated by fire-resistant boundaries to contain and limit fire spread, as defined by SO...
- What is Firing Exercises? Planned military or naval operations in which weapons are fired in designated sea areas, usually requiring ships to keep...
- What is Flood Control? Procedures and systems used to limit, contain, and remove water ingress after hull damage or compartment flooding.
- What is Flood Control? Actions and onboard systems used to limit, isolate, or remove flooding in compartments, such as watertight doors, pumps,...
- What is Flood Tide Prediction? Forecast information regarding the timing and height of the next incoming (flood) tide, crucial for safe navigation and ...
- What is Flooded Compartment? A watertight section of a vessel that has unintentionally filled with seawater due to hull breach or system failure.
- What is Flooding Alarm? An audible and/or visual alarm triggered automatically or manually when water ingress is detected in compartments below ...
- What is Flooding Drill? A mandatory exercise in which crew practice responding to flooding, including detection, boundary establishment, and use...
- What is Fog Patch Advisory? Notice to mariners of localised fog banks that may suddenly reduce visibility and require speed reduction or additional ...
- What is Following Vessel? A vessel which is navigating behind another in the same direction, often in a convoy or traffic lane.
- What is Foot Valve? A non-return valve installed at the lower end of a suction line in cargo or ballast tanks, designed to prevent backflow ...
- What is Fouled Propeller? A condition where the propeller is entangled with ropes, nets, or debris, affecting maneuverability.
- What is Freezing Fog Advisory? An advisory issued to warn vessels of freezing fog conditions, which may cause ice accumulation on decks, equipment, and...
- What is Freezing Rain Warning? GMDSS forecast message indicating super-cooled rain likely to freeze on contact, causing rapid ice accretion on decks an...
- What is Freezing Spray Warning? GMDSS meteorological warning that sea spray will freeze on exposed surfaces causing topside icing hazards.
- What is Frequent Interference? Repeated radio noise or overlapping transmissions that degrade VHF communication quality on the working channel.
- What is Freshwater Generator? A shipboard device that produces potable freshwater from seawater using evaporation and condensation, essential for crew...
- What is Frontal Passage Warning? A formal advisory issued by maritime authorities warning vessels of an approaching frontal system likely to bring sudden...
- What is Fuel Changeover Procedure? A documented process for safely switching the ship’s fuel supply from one grade or type to another, often to comply with...
- What is Fuel Filter Bypass? A mechanism allowing fuel to flow around a clogged filter element to maintain engine operation in emergencies, potential...
- What is Fuel Oil Homogenizer? A machine that breaks down asphaltene clusters and ensures uniform mixing of fuel oil, improving combustion quality and ...
- What is Fuel Oil Transfer? The process of pumping fuel oil from one tank to another or to the engine, requiring strict adherence to MARPOL, safety,...
- What is Fuel Oil Viscosity? The measure of a fuel oil’s resistance to flow, critical for engine injection and atomization; monitored and regulated i...
- What is Fuel Rack Position? The precise setting of the fuel control rack that determines the amount of fuel delivered to each cylinder of a diesel e...
- What is Full Ahead Bell? Engine telegraph order instructing propulsion at full engine speed ahead, typically used in open sea or to quickly gain ...
G
- What is Gale Warning? A warning issued to mariners when sustained winds of Beaufort Force 8 or higher (34–40 knots) are expected or occurring ...
- What is Garbage Discharge Record? A mandatory logbook entry or record made by the ship to document every instance of garbage discharge or disposal at sea ...
- What is Gas Detection Panel? A monitoring system that displays real-time readings from gas detectors, providing alarms if hazardous or flammable gas ...
- What is Gas Freeing? The process of removing hazardous or toxic vapours from tanks by ventilation, rendering them safe for entry, inspection,...
- What is Generator Load Test? A controlled procedure for verifying a generator’s capability to supply rated power by gradually applying electrical loa...
- What is Generator Synchronization? The process of matching the voltage, frequency, and phase of an incoming generator to the busbar before connecting it in...
- What is Give Way? An instruction for a vessel to yield in order to avoid collision and allow another vessel to pass as per the COLREGS.
- What is Glide Path Control? Continuous monitoring and adjustment of a vessel’s approach trajectory to the berth, ensuring a smooth, controlled entry...
- What is Global Navigation System? A satellite-based navigation system such as GPS, GLONASS, Galileo, or BeiDou, providing worldwide position, navigation, ...
- What is GMDSS Weather Bulletin? Scheduled meteorological broadcast issued via NAVTEX, HF, MF or satellite under the Global Maritime Distress and Safety ...
- What is Governor Response Test? A routine operational test to verify that the engine speed governor responds correctly to load changes, ensuring engine ...
- What is Greenhouse Gas Inventory? Comprehensive report of CO₂, CH₄ and N₂O emissions from vessel operations for regulatory compliance and environmental ma...
- What is Grounding Risk? Potential danger of the vessel running aground due to shallow water or navigational error.
- What is Growler Ice Warning? Alert indicating presence of small, dense glacial ice blocks (growlers) scarcely visible above water, posing collision r...
- What is Guard Channel? A designated VHF radio frequency used for emergency, distress, or mandatory communication monitoring.
- What is Gyro Compass Error? An inaccuracy or malfunction of the ship’s gyro compass, resulting in incorrect heading information displayed to bridge ...
- What is Gyro Unreliable? A warning that the vessel’s gyrocompass cannot be trusted for accurate heading information.
H
- What is Half Ahead Bell? Engine telegraph order instructing propulsion at half engine speed ahead, used for moderate manoeuvring or departure fro...
- What is Harbour Pilot Disembarkation? The controlled process by which the harbour pilot safely leaves the vessel after completing the inbound or outbound pass...
- What is Harbour Pilot Embarkation? The procedure for safely boarding the harbour pilot at sea or at the entrance of the port using a pilot ladder or launch...
- What is Harbour Speed Limit? The officially published maximum speed permitted for vessels within a designated harbour or port area, set by local auth...
- What is Harbour Traffic? Collective term for the movement of vessels and craft within port limits as monitored by VTS or Harbour Master.
- What is Hard Port? Helm order instructing the rudder to be put fully to port (left) for maximum turning effect.
- What is Hard Starboard? Helm order instructing the rudder to be put fully to starboard (right) for maximum turning effect.
- What is Haze Observation Report? A message reporting reduced visibility due to haze, specifying affected areas and visibility range, commonly issued for ...
- What is Heading Rate Control? Autopilot or manual feedback setting that governs how rapidly the vessel’s heading may change, expressed in degrees per ...
- What is Heading Reference Failure? A malfunction or loss of accuracy in the ship’s heading reference system, such as gyro or magnetic compass, affecting na...
- What is Heat Wave Watch? Pre-warning by meteorological authority that sustained high air temperatures are likely within 48 h, possibly affecting ...
- What is Heating Coil? A tubular device installed inside cargo tanks for indirect heating of cargoes, especially heavy oils, to maintain suitab...
- What is Heavy Rain Warning? GMDSS meteorological message signalling precipitation rate ≥ 50 mm in 6 h, causing reduced visibility and risk of runoff...
- What is Heavy Snow Warning? Forecast advising imminent heavy snowfall reducing visibility below 0.5 nm and affecting mooring or channel transit.
- What is Heavy Traffic? A situation or area where a high density of vessels requires heightened vigilance, reduced speed, and strict adherence t...
- What is Helicopter Transfer? Operation involving the embarkation or disembarkation of personnel or cargo by helicopter to or from a vessel, requiring...
- What is Helm Order Acknowledgement? The required verbal response by the helmsman to confirm receipt and understanding of a helm order from the officer of th...
- What is Helm Synchronization Alarm? An alert indicating a mismatch between helm (steering wheel) position and rudder angle, requiring immediate attention to...
- What is Helm Transfer Procedure? The standardised method for transferring control of the ship’s steering from one helm station or operator to another, en...
- What is High Level Alarm? A critical warning system that alerts crew when the liquid in a tank approaches a designated high point, preventing over...
- What is High Pressure Fuel? Fuel oil pressurized to high levels for injection into main engine cylinders, delivered by high-pressure pumps as specif...
- What is High Pressure Ridge? An elongated area of high atmospheric pressure, typically associated with calm weather and stable sea conditions.
- What is High Voltage? Warning regarding electrical systems or cables carrying dangerous voltage levels, requiring safety precautions.
- What is High Wind Berthing? A berthing operation performed in high wind conditions, requiring specific techniques, increased tug assistance, or thru...
- What is Hold Position? Instruction to maintain current position, either at anchor or underway, until further orders are received.
- What is Hose Connection? The act of securing cargo hoses between ship and shore, or between tanks and manifolds, ensuring a leak-free and safe ca...
- What is Hose Testing? The procedure of pressure-testing cargo hoses with water or air before use to ensure integrity and compliance with inter...
- What is Hurricane Force Wind? Wind of Beaufort scale 12 (≥ 64 kn) producing phenomenal seas; reported in Metarea bulletins as force 12.
- What is Hurricane Warning? A formal announcement by maritime or meteorological authorities indicating that hurricane conditions, including very hig...
- What is Hydraulic Oil Cooler? A heat exchanger used to maintain the temperature of hydraulic oil within safe operating limits for reliable system perf...
- What is Hydrogen Sulphide? A highly toxic and flammable gas (H₂S) present in some crude oils and products; detection and management are critical fo...
- What is Hydrophore Pressure Tank? A pressurized tank in a ship’s fresh water system that maintains constant water pressure for domestic and service use th...
- What is Hydrostatic Trim Shift? Change in a vessel’s longitudinal trim resulting from variations in hydrostatic forces due to ballast, cargo, or water d...
I
- What is Ice Accretion Warning? Notice that superstructure icing rate exceeds 2 cm h⁻¹ due to freezing precipitation or spray, requiring anti-icing meas...
- What is Ice Drift Prediction? Forecast of movement and speed of pack or floe ice issued by ice service for route planning.
- What is Ice Edge Report? Update giving the geographic position of the ice edge separating open water from pack ice, critical for polar routing.
- What is Iceberg Drift Forecast? A prediction of the future movement and position of icebergs in a given maritime area, based on meteorological and ocean...
- What is Increase Speed? Instruction to make more way through the water to meet traffic, tidal, or berth scheduling requirements.
- What is Incremental Power Burst? A technique involving small, timed increases in engine or thruster power to control a vessel’s position or heading preci...
- What is Inert Gas? A non-flammable gas used to reduce the oxygen content in cargo tanks, preventing explosion risks during the transport or...
- What is Inert Gas Generator? A shipboard unit that produces inert gas, primarily used on tankers to maintain a non-flammable atmosphere in cargo tank...
- What is Inertia Control Strategy? The procedure and logic used to manage a vessel's inertia during changes in speed or heading, optimizing response time a...
- What is Inerting Operation? The process of introducing inert gas into cargo tanks to reduce oxygen concentration, preventing flammable mixtures duri...
- What is Information Broadcast? A general transmission on VHF or NAVTEX to inform vessels about safety, weather, traffic or other operational matters.
- What is Inshore Traffic Zone? A coastal area, adjacent to the landward side of a traffic separation scheme, intended for use by vessels not using the ...
- What is Integrity Monitoring Alarm? An alarm signaling a failure or inconsistency detected in the position integrity monitoring system, requiring immediate ...
- What is Intend Overtake? Announcement that a vessel plans to pass another vessel ahead on a specified side in accordance with the COLREGS.
- What is Interaction Zone Warning? Advisory issued when proximity of shallow banks or passing vessels may cause hydrodynamic interaction affecting steering...
- What is Intercooler Differential? The pressure or temperature difference measured across the intercooler, used to detect fouling or blockages affecting en...
J
- What is Jacket Cooling Water? The fresh water circulating through the engine’s cylinder jacket to absorb heat and prevent overheating during operation...
- What is Jamming Detected? Notification that radio communication is being interfered with by intentional or unintentional signal jamming.
- What is Join Convoy? Instruction or request for a vessel to assemble and proceed as part of an organized convoy for mutual safety, security, ...
- What is Joystick Manoeuvring Mode? A control setting that allows a vessel to be steered and positioned using a joystick, integrating thrusters and main pro...
K
- What is Keep Clear? Instruction to remain at a safe distance from a specified vessel, area, or hazard.
- What is Keep Clear? Instruction to maintain a safe distance from a specified vessel, area, or hazard to prevent collision, obstruction, or r...
- What is Keep Listening? Instruction to maintain a listening watch on a specified VHF channel for further communication or safety messages.
- What is Kickback Line? A pipeline connecting cargo manifold or transfer system back to the tank, used for circulation or pressure control durin...
- What is Kickback Line? A pipeline connecting the manifold or transfer system back to a tank, used for circulating cargo, line clearing, or pres...
L
- What is Laser Docking System? High-precision laser array projecting range and angular deviation data to vessel displays for centimetre-level berthing ...
- What is Lead Angle Correction? Adjustment applied to ship’s heading to offset predicted set and drift so that actual track leads planned approach line.
- What is Leading Light Alignment? The process of navigating a vessel by visually aligning two or more fixed leading lights (range lights), ensuring the ve...
- What is Leeway Angle Estimate? The calculated or visually assessed angle between a vessel’s heading and actual course over ground, caused by wind or cu...
- What is Let Go All? Final order to release all mooring lines, allowing the vessel to depart from berth.
- What is Let Go Starboard? Mooring command to release or cast off the starboard (right) mooring line or cable.
- What is Lifeboat Drills? Regular training exercises involving the launching and operation of lifeboats as per SOLAS requirements.
- What is Lightning Activity Warning? Alert issued when frequent cloud-to-ground or cloud-to-cloud lightning poses immediate risk to deck personnel and sensit...
- What is Line Displacement? The process of clearing a pipeline by pushing cargo or liquid out with another medium, usually to ensure product segrega...
- What is Line Flushing? Process of cleaning cargo or ballast pipelines by circulating water, air, or another fluid to remove remaining product a...
- What is Line Flushing? Process of cleaning pipelines by circulating water, air, or another fluid to remove product and contaminants.
- What is Line Handling? The operation of preparing, passing, securing, and tending mooring lines to assist in berthing or unberthing a vessel.
- What is Line Pigging? Mechanical cleaning of pipelines using a device known as a 'pig' to remove residues or blockages and ensure efficient fl...
- What is Listening Watch? Continuous monitoring of a specified VHF or radio frequency for traffic, safety, or distress calls.
- What is Listening Watch? Continuous monitoring of a designated VHF or MF/HF radio channel for traffic, safety, or distress messages, as required ...
- What is Live Pilot Plug? An active data connection port on the bridge that provides real-time navigational data from the ship's ECDIS or AIS syst...
- What is Load Dependent Start? An automatic function of the ship’s power management system that starts or stops auxiliary engines or generators based o...
- What is Load On Top? A cargo operation method in which the slops or residues in a tank are allowed to settle and then new cargo is loaded abo...
- What is Load Shedding System? An automated system that disconnects non-essential electrical loads to prevent total blackout when generator capacity is...
- What is Loadicator Check? A procedure to verify cargo and ballast loading plans and actual weights using a shipboard stability calculator (loadica...
- What is Loading Arm? A movable articulated mechanical arm used at terminals to transfer liquid cargo between ship and shore through the cargo...
- What is Loading Master? The senior person responsible for supervising all cargo operations on board a tanker during loading, ensuring safety, co...
- What is Loading Sequence? The planned order and method for loading cargoes into tanks to maintain vessel stability, prevent contamination, and com...
- What is Loading Sequence? The planned order and method for loading cargoes into tanks to maintain stability, prevent contamination, and comply wit...
- What is Loadline Compliance? The act of ensuring that a vessel's draft and freeboard remain within limits set by the assigned Plimsoll mark and inter...
- What is Local Control Stand? A designated engine room console enabling manual operation and monitoring of main engine or machinery independently of t...
- What is Local Traffic? Vessels operating within a port, harbour, or defined coastal area, often with priority rules or reporting obligations fo...
- What is Lost Propulsion? Loss of ability to propel the vessel due to engine failure or other mechanical issues.
- What is Low Load Operation? Operating main engines or generators at reduced output, often during harbor stay or maneuvering, requiring special monit...
- What is Low Pressure Area? A meteorological region where atmospheric pressure is lower than surrounding areas, often associated with unsettled weat...
- What is Lubricating Oil Purifier? A centrifugal device used on board to remove water and contaminants from lubricating oil, ensuring optimal engine operat...
M
- What is Magnetic Compass Variation? The angular difference between true north and magnetic north, affecting compass readings on board ships.
- What is Magnetic Interference? Disruption or deviation of magnetic compass readings due to local magnetic fields, ship’s structure, or electrical equip...
- What is Main Air Receiver? A large pressure vessel that stores compressed air for main engine starting and other critical pneumatic systems, mainta...
- What is Main Bearing Oil? Lubricating oil supplied to the main engine's main bearings, essential for reducing friction and preventing overheating ...
- What is Main Engine Control? The central console or system used to monitor and operate the ship’s main propulsion engine, including remote start, sto...
- What is Main Engine Indicator? An instrument that displays key operational parameters of the main engine, such as load, RPM, and cylinder pressures, ai...
- What is Main Engine Reversal? A maneuver in which the main engine’s rotation direction is reversed, allowing the ship to go astern or stop.
- What is Main Switchboard Panel? The primary electrical distribution panel on board controlling power supply to all vital systems and equipment, designed...
- What is Man Overboard? Emergency indicating that a person has fallen from a vessel into the water and immediate rescue actions are required.
- What is Mandatory Reporting Scheme? A regulatory system requiring vessels to provide voyage information at specified locations or intervals, typically enfor...
- What is Manifold Crossover? A pipe or valve arrangement that allows transfer between different cargo manifolds, enabling flexibility in cargo handli...
- What is Manifold Crossover? A pipe or valve arrangement that allows transfer between different cargo manifolds for flexible or emergency cargo handl...
- What is Manifold Pressure? The pressure measured at the cargo manifold during loading or discharging, crucial for monitoring safe and efficient car...
- What is Manoeuvring Lever Position? The selected position of the manoeuvring lever on the bridge or engine control console, determining direction and speed ...
- What is Manoeuvring Speed Check? The process of verifying and confirming the vessel’s speed through the water is suitable for safe manoeuvring during ber...
- What is Marine Litter Report? A report made to authorities or VTS regarding observed floating or drifting marine debris that may pose a hazard to navi...
- What is Master Pilot Exchange? A formal communication process between the ship’s master and the pilot to share essential navigation information, plans,...
- What is Mayday Relay? A distress message transmitted by a vessel or station on behalf of another vessel, aircraft, or person in grave and immi...
- What is Meet Her? Helm order given to check the vessel’s swing and prevent further turning, typically after a large rudder movement.
- What is Metarea Forecast Request? Vessel’s formal demand via GMDSS for the latest meteorological forecast for a specific NAVAREA/METAREA region.
- What is Meteorological Report? Official broadcast of weather conditions, warnings, and forecasts relevant to maritime navigation.
- What is Midships Rudder? Helm order to bring the rudder to the midships (zero angle) position, aligning with the vessel’s centerline.
- What is Minimum Breakout Speed? The lowest speed required to break the anchor free from the seabed and commence recovery.
- What is Minimum Steering Speed? The lowest speed at which the vessel maintains effective steering control, typically specified by the vessel’s maneuveri...
- What is Mist Formation Advisory? An official advisory indicating that atmospheric conditions are favorable for mist development, which may lower visibili...
- What is Mooring Operations? All procedures related to securing or unmooring a vessel to or from a berth, buoy, or anchorage.
- What is Mooring Tension Monitoring? Real-time supervision of static and dynamic loads on mooring lines to maintain safe tension limits under environmental f...
- What is Motion Reference Unit? A device that detects and reports a vessel’s six degrees of motion, used to support dynamic positioning and other naviga...
- What is Move Astern? Order or report indicating the vessel is moving, or must move, backward relative to its heading.
N
- What is Navigation Warning? Official broadcast of hazards, obstructions, or operational restrictions that may affect safe navigation.
- What is Navigation Warning? A formal broadcast or message informing mariners of navigational hazards, new obstructions, or significant changes in ch...
- What is Nitrogen Purging? Introduction of nitrogen gas into tanks or pipelines to remove oxygen or flammable vapours, ensuring an inert atmosphere...
- What is No Clearance? Notification that the vessel does not have authorization or permission to enter, leave, or transit a specific area, port...
- What is No Response? Phrase used to indicate that a called station has not replied within a reasonable time, requiring repeat or escalation o...
- What is Noise Abatement Procedure? Harbour authority directive requiring vessels to minimise machinery and whistle noise, especially at night, to protect n...
- What is Non-Return Valve Test? A procedural check to verify that a non-return (check) valve allows fluid flow in only one direction, preventing backflo...
- What is Number Persons? Total count of persons (crew and passengers) on board, often requested for safety or SAR purposes.
O
- What is Obstruction Reported? Notification that a hazard, such as a floating object or wreck, is present and may endanger navigation.
- What is Obstruction Reported? Notification that a physical hazard, such as a wreck, buoy, or floating object, has been observed in a navigable area, r...
- What is Occluded Front Alert? Notification that a mature occluded front will pass the vessel’s vicinity, often associated with variable winds and squa...
- What is Ocean Heat Content? Measure of thermal energy stored in the upper ocean layers, used to assess cyclone potential and climate trends.
- What is Oceanographic Data Report? A formal report or transmission containing oceanographic data such as temperature, salinity, current, and sea state, as ...
- What is Oil Discharge Monitor? An electronic device used to measure and control oil content in discharged water, ensuring compliance with MARPOL and po...
- What is Oil Mist Detector? A fixed device that continuously monitors and detects oil mist concentrations in engine crankcases to prevent explosions...
- What is Oil Pollution? Presence or discharge of oil into marine waters from a vessel or facility, constituting a reportable incident and requir...
- What is Oil Spill Alert? Immediate notification that mineral oil is observed on sea surface requiring containment and reporting under MARPOL 73/7...
- What is On Scene? Statement indicating that the vessel, aircraft, or rescue unit has arrived at the position of an incident or casualty.
- What is Operation Completed? Notification that a particular port, cargo, or navigational operation has been fully finished.
- What is Overfill Alarm? An automatic safety device that activates an audible and visual alert when liquid in a tank approaches a critical high l...
- What is Overtaking Prohibition Zone? A defined sector of a channel or waterway where overtaking by vessels is prohibited for safety reasons, often due to res...
P
- What is Pan Pan? A radiotelephony urgency signal indicating a situation urgent but not immediately life-threatening; always spoken in Eng...
- What is Parallel Index Line? A radar-derived reference line drawn parallel to the vessel's intended track, used to monitor cross-track error by keepi...
- What is Parallel Index Method? A radar navigation technique in which fixed radar echoes are kept on predetermined parallel lines to verify the vessel r...
- What is Pig Receiver? A pressure vessel or chamber installed at the end of a pipeline to receive the pig after cleaning, used in cargo or ball...
- What is Pig Receiver? A pressure vessel or chamber at the end of a pipeline to receive the pig after cleaning or product transfer, used in car...
- What is Pilot Boarding? Designated process and location where a maritime pilot embarks or disembarks from a vessel.
- What is Pilot Boarding Ground? A designated area, marked on charts, where the pilot boards or disembarks from a vessel, usually at port approaches or f...
- What is Pilot Ladder Rigged? A pilot ladder correctly secured and deployed over the ship’s side, ready for safe boarding or disembarkation of the pil...
- What is Pilotage Passage Plan? A detailed route plan, prepared jointly by the master and pilot, outlining intended track, waypoints, speed, and manoeuv...
- What is Piston Gauge? A pressure measurement device using a piston and cylinder assembly, typically used to calibrate pressure systems on tank...
- What is Pitching Moment Control? The regulation of longitudinal pitching moments of a vessel, using ballast or thrusters, to ensure stability and reduce ...
- What is Pivot Point Estimation? Calculation of the vessel’s instantaneous longitudinal pivot point to predict turn characteristics in low-speed manoeuvr...
- What is Pollution Control Exercise? Planned harbour drill simulating oil-spill response, including boom deployment, skimmer operation and multi-agency commu...
- What is Position Doubtful? Phrase used to indicate that the vessel's current navigational position cannot be reliably confirmed and may be inaccura...
- What is Position Fix Abort? Command to discontinue planned position fixing process when results are unreliable or time-critical manoeuvre takes prio...
- What is Position Integrity Monitoring? Continuous verification of the reliability and accuracy of the ship’s position as provided by navigation systems.
- What is Position Passed? Notification that a vessel has just crossed or gone abeam of a specified position, buoy, or waypoint.
- What is Power Take Off? A mechanical device that transfers engine power to auxiliary equipment such as generators or pumps, typically via a shaf...
- What is Precautionary Area? A defined area where vessels must navigate with particular caution, often due to traffic convergence, hazards, or comple...
- What is Pressure Regulating Valve? A valve used to maintain a set pressure in a piping system by opening or closing in response to changes in upstream or d...
- What is Pressure Ridge Alert? A notice regarding the formation or presence of elevated ice ridges on sea ice, which may pose navigational hazards to v...
- What is Pressure Vacuum Valve? A safety device on cargo tank vent lines that automatically opens or closes to maintain safe pressure and prevent overpr...
- What is Proceed Channel? Instruction to enter and follow a designated fairway or channel for safe navigation as directed by VTS or port authority...
- What is Proceeding Inbound? Statement or report that a vessel is moving towards a port or entering a specific area.
- What is Propeller Guard Check? Inspection of the propeller guard for integrity and correct positioning before manoeuvring or departure, ensuring safe p...
- What is Propeller Pitch Synchronization? Matching of pitch angles on controllable-pitch propellers to balance thrust and avoid yaw during twin-screw operations.
- What is Propeller Walk Assessment? Evaluation of sideways movement (walk) caused by propeller rotation while making headway or sternway at low speed.
- What is Propulsion Control Panel? The main interface on the bridge or in the engine room for controlling the vessel’s propulsion system, including speed, ...
- What is Public Correspondence? Telecommunications service on board for the exchange of messages between ship and shore for public or commercial use.
- What is Pump Coupling Guard? A mechanical safety cover installed over rotating pump couplings to prevent injury and contain parts in the event of fai...
- What is Pump Performance? Assessment and monitoring of cargo pump efficiency, capacity, and operation to ensure optimal transfer rates and detect ...
- What is Pump Room Ventilation? The process and system for providing safe airflow in the pump room to prevent accumulation of explosive vapors and maint...
- What is Pump Strainer? A filtering device fitted to the suction side of cargo or ballast pumps to prevent entry of solid particles and debris t...
- What is Purge Valve? A valve used to expel unwanted gases or residues from cargo lines, tanks, or machinery spaces, ensuring safe and inert c...
- What is Purifier Sludge Tank? A tank designed to collect and store sludge and contaminants removed by fuel or lube oil purifiers before final disposal...
- What is Purifier Throughput Test? An operational procedure to verify the flow rate and performance efficiency of the lubricating or fuel oil centrifugal p...
Q
- What is Quadrant Search? A systematic search pattern, typically used in SAR operations, covering four quadrants from a datum point to locate pers...
- What is Quick Stop Manoeuvre? Emergency procedure whereby engine is set full astern and helm hard over to rapidly stop vessel’s forward motion within ...
R
- What is Radar Echo Offset? The adjustment of the radar image to compensate for systematic error or offset, ensuring true target positions correspon...
- What is Radar Gauging? Use of radar technology to measure tank level, ullage, or interface without contact, widely used for precise monitoring ...
- What is Radar Overlay Display? The presentation of radar information directly on the electronic chart display, enabling visual correlation of radar tar...
- What is Radar Plotting Manual? A publication or onboard manual containing standardized instructions, techniques, and worksheets for manually plotting r...
- What is Radio Silence? A formal order requiring all stations to cease transmitting on a frequency, usually for distress or security reasons.
- What is Radiofax Chart Receipt? Confirmation that a complete facsimile weather chart has been successfully received via HF radio and is ready for naviga...
- What is Range Light Alignment? The navigation technique of steering a vessel so that two range lights, one behind the other, appear vertically aligned,...
- What is Rate Of Turn? The speed at which a vessel changes its heading, typically measured in degrees per minute and displayed on the bridge in...
- What is Rate Stabilization Mode? Autopilot setting that dampens oscillations by keeping rate of turn constant once a target value is reached during manoe...
- What is Recommended Traffic Lane? A charted route within a traffic separation scheme or recommended track designed for the safe passage of vessels, but no...
- What is Reduced Visibility Warning? A formal alert issued to vessels when fog, mist, precipitation, or other factors are expected to lower visibility below ...
- What is Reduction Gearbox Oil? Lubricating oil specifically formulated for use in reduction gearboxes, ensuring smooth power transmission and preventin...
- What is Reflux Valve? A valve installed to control the return flow of condensed vapors or liquids back into a tank or system for process or sa...
- What is Remote Control System? A system allowing the operation and monitoring of shipboard machinery or equipment from a location other than the equipm...
- What is Remote Standby Pump? A pump located outside the machinery space, operated remotely to provide emergency or backup fluid transfer capability.
- What is Report Damage? Instruction to inform relevant authorities or stations of any structural, mechanical, or environmental damage sustained,...
- What is Report Fire? A prompt or instruction to immediately communicate the occurrence, location, and extent of a fire on board or ashore, us...
- What is Resume Passage? Order authorising a vessel to continue its original voyage after a temporary stop, alteration, or holding pattern.
- What is Reverse Thrust Kick? A short, controlled burst of astern propulsion to quickly reduce a vessel’s forward speed or stop movement during precis...
- What is Reversing Momentum Check? Verification that astern power has arrested forward momentum before changing engine orders during docking sequence.
- What is Reversing Momentum Check? Verification manoeuvre carried out to ensure the vessel’s astern power can promptly overcome residual forward momentum b...
- What is Roll Period Estimate? An evaluation of the time taken for a vessel to complete one full roll oscillation, essential for stability analysis and...
- What is Rudder Angle Limiter? Device or setting restricting maximum rudder angle to prevent over-steer at speed or protect steering gear.
- What is Rudder Effectiveness Loss? Reduction in steering response due to low water flow over rudder, cavitation, or mechanical limitation.
S
- What is Safe Water Mark? IALA buoyage mark indicating there is navigable water all around the mark.
- What is Safety Broadcast? Official VHF or NAVTEX message to all ships concerning safety-related information or urgent warnings.
- What is Satellite Position Fix? A position determined using satellite navigation signals, typically from systems like GPS or GLONASS, used for precise s...
- What is Scavenge Air Cooler? A heat exchanger that cools scavenge air supplied to main engine cylinders, increasing air density and engine efficiency...
- What is Sea Chest Valve? A seacock or valve fitted at the hull sea chest, controlling seawater intake for engine cooling, ballast, or firefightin...
- What is Sea Fog Warning? Notice that horizontal visibility at sea will fall below one kilometre due to advection or radiation fog.
- What is Sea Ice Concentration? A measure (usually in tenths) of the area of a sea region covered by ice, provided in ice bulletins to support safe navi...
- What is Sea State Report? Periodic description of significant wave height, period and swell state transmitted for routing and safety assessments.
- What is Sea Surface Temperature? Measured or satellite-derived temperature of ocean top centimetre, critical for routing, icing and cyclogenesis forecast...
- What is Seawater Cooling Pump? A pump supplying seawater to coolers for cooling main and auxiliary machinery, essential for temperature regulation and ...
- What is Segregated Ballast? Ballast water held in tanks completely separated from cargo oil and fuel systems, used to ensure no contamination occurs...
- What is Severe Gale Signal? An official maritime signal indicating imminent or present severe gale conditions (Beaufort Force 9–10) requiring vessel...
- What is Severe Storm Bulletin? Official GMDSS warning message indicating winds ≥ Beaufort 10, heavy seas and reduced visibility within forecast area.
- What is Shaft Bearing Temperature? The measured temperature of a ship’s main propulsion shaft bearing, monitored continuously to prevent overheating and po...
- What is Shaft Power Limitation? A set operational restriction on the maximum shaft power output, typically to comply with EEXI and MARPOL Annex VI energ...
- What is Shaft Revolution Counter? A device or system that records the number of revolutions of the propulsion shaft, providing critical speed and distance...
- What is Sheer Off Control? Active steering or thruster management to prevent a vessel from swinging away (sheering off) from its intended track or ...
- What is Ship Weather Observation? Recorded meteorological observations from ships, submitted to authorities or meteorological agencies for forecasting and...
- What is Sideforce Compensation Plan? A navigational strategy to counteract lateral forces (wind, current, propeller wash) that may cause a vessel to drift si...
- What is Sideslip Angle Monitoring? Continuous observation of vessel’s lateral drift angle relative to track to ensure safe approach trajectory during docki...
- What is Single Up Lines? Order to reduce the number of mooring lines on each bollard to one, preparing the vessel for departure.
- What is Slip Calculation Mode? A navigational mode where a vessel’s slip—the difference between theoretical and actual movement—is monitored and calcul...
- What is Slipway Approach Track? The planned or observed vessel path when aligning for entry onto a slipway, critical for safe launching or hauling opera...
- What is Slop Treatment? The onboard process of managing and separating oil residues, tank washings, and mixtures for discharge or retention in s...
- What is Sloshing Assessment? Evaluation of the movement and impact of liquid cargo within a tank caused by ship motion, to assess risks of structural...
- What is Slow Ahead Bell? The engine telegraph order for slow speed ahead, typically used during precise manoeuvring, docking, or when entering co...
- What is Soot Blower Operation? The process of using a soot blower system to remove accumulated soot from boiler tubes or exhaust gas economizers, ensur...
- What is Squall Line Alert? Notification that organised line of squalls with gusts ≥ 34 kn is approaching, often ahead of cold front.
- What is Squat Effect Allowance? The additional draught margin applied to account for the increased draught of a vessel due to the squat effect in shallo...
- What is Stability Calculation? The process of determining a vessel’s ability to remain upright and safe under current loading conditions by calculating...
- What is Standby Lubrication Pump? A backup pump in the engine room that automatically or manually provides lubrication oil flow if the main pump fails, en...
- What is Standby Main Engines? Order for main engines to be ready for immediate use, typically before departure, arrival, or manoeuvring.
- What is Start Air Compressor? A compressor that supplies high-pressure air for starting main and auxiliary engines, essential for engine readiness and...
- What is Starting Air Distributor? A mechanical device that controls the timing and sequence of starting air supplied to engine cylinders during main engin...
- What is Starting Air Filter? A filter installed in the starting air system to remove contaminants from compressed air before it reaches engine cylind...
- What is Static Accumulation? The buildup of electrical charge on surfaces in a tank or pipeline during cargo transfer, creating a risk of discharge a...
- What is Steam Dump Valve? A valve that releases excess steam from boilers or turbines to prevent overpressure, often routed to the atmosphere or c...
- What is Steering Feedback Loop? A control system that continually monitors rudder position and vessel heading to automatically correct steering and main...
- What is Steering Gear Alarm? A warning signal indicating malfunction or abnormal condition in the steering gear system, requiring immediate crew inve...
- What is Steering Gear Changeover? The act of switching from one steering gear system or power unit to another, often for redundancy or in case of equipmen...
- What is Stern Tube Seal? A sealing device at the exit point of the ship’s propeller shaft through the hull, preventing water ingress and oil leak...
- What is Stern Tug Position? The designated location of a tug at the stern of a vessel, used to provide pulling or braking force during manoeuvring, ...
- What is Sternway Speed Alarm? An alarm triggered when a vessel's sternway (reverse movement) exceeds a preset speed threshold, alerting crew to possib...
- What is Stop Main Engines? Engine telegraph order to cease all propulsion; used when vessel is to remain stationary or fully secured at berth.
- What is Storm Surge Advisory? Warning that abnormal sea-level rise due to cyclonic surge is expected in coastal area, requiring preventive mooring and...
- What is Storm Warning? A formal notification from maritime or meteorological authorities indicating strong winds, heavy seas, and potentially h...
- What is Stress Monitoring? Continuous assessment of ship or tank structure for stress levels, especially during cargo operations, to ensure limits ...
- What is Stripping Line? A dedicated pipeline onboard a tanker used to remove the final residues or small quantities of cargo remaining in tanks ...
- What is Stripping Pump? A pump specifically used for removing remaining cargo or residues from tanks, pipelines, or bilges after main discharge ...
- What is Suction Effect Estimate? The assessment of negative pressure that draws a vessel toward another object or structure during close-quarter manoeuvr...
- What is Surface Current Warning? Official MSI or VHF message advising mariners that abnormally strong or variable surface currents exist in a defined are...
- What is Surface Pressure Chart? Synoptic weather map depicting isobars and pressure systems at mean sea level, used for routeing decisions.
- What is Surge Motion Control? Management of longitudinal oscillations of vessel while moored, using winch tension adjustments or tug assistance to pre...
- What is Surge Pressure? A sudden increase in pressure within a cargo pipeline or tank, usually caused by rapid valve closure or pump operation, ...
- What is Swell Direction Report? Statement giving the dominant direction, height and period of the prevailing ocean swell for route planning and seakeepi...
- What is Synoptic Code Report? A standardized numerical weather message (per WMO/IMO) reporting synoptic-scale observations, transmitted by ships for m...
T
- What is Tactical Diameter Evaluation? Assessment of the vessel’s maximum transverse distance travelled during a turning circle with constant rudder angle at f...
- What is Tank Atmosphere? The composition and quality of gases present inside a cargo tank, monitored to ensure safety from flammable, toxic, or i...
- What is Tank Padding? Process of introducing inert gas (often nitrogen) into the tank vapor space to maintain safe conditions, prevent air ing...
- What is Tank Pressurization? Maintaining a set positive pressure in a cargo tank, often using inert gas, to prevent air entry and reduce fire or expl...
- What is Tank Radar? Radar-based electronic device for real-time measurement of cargo tank level, ullage, or interface, providing accurate, n...
- What is Tank Recirculation? The process of circulating cargo within a tank, using pumps and pipelines, to maintain uniform temperature and prevent s...
- What is Tank Scavenging? Process of removing residues or remaining liquids from cargo tanks after discharge, often using air, inert gas, or pumps...
- What is Tank Sounding System? An electronic or manual system for measuring liquid levels in ship tanks, such as fuel, ballast, or fresh water, to ensu...
- What is Tank Venting? The controlled release of vapours from a cargo tank through dedicated venting systems to prevent overpressure or vacuum ...
- What is Temperature Logging? The continuous recording of temperature measurements within cargo tanks or lines to ensure safe transport and quality co...
- What is Terminal Liaison? The appointed person or office responsible for communication and coordination between ship and terminal during cargo ope...
- What is Terminal Liaison? The person or office responsible for communication and coordination between ship and terminal during cargo operations.
- What is Terrestrial Position Fix? A position established by bearings or distances to known land features or aids to navigation, not using satellites.
- What is Thermal Oil Heater? A unit designed to heat thermal oil used as a medium for transferring heat to fuel tanks, cargo systems, or other shipbo...
- What is Thrust Allocation Model? A computational approach for optimally distributing propulsion thrust among multiple thrusters to achieve desired vessel...
- What is Thruster Efficiency Coefficient? A calculated ratio indicating how effectively a vessel’s thruster converts power input into thrust for manoeuvring opera...
- What is Thruster Run Down? The process of safely reducing thruster power and shutting down the units after manoeuvring or while leaving station kee...
- What is Thruster Run Up? A procedure where thrusters are gradually powered up and tested before being engaged for manoeuvring or station keeping.
- What is Thunderstorm Outlook? Prognostic bulletin giving probability, timing and movement of convective cells within shipping area.
- What is Tidal Stream Update? New information on rate and set of tidal current issued by VTS or hydrographic authority for local area.
- What is Tidal Surge Warning? An official alert issued to vessels regarding an abnormally high rise of sea level due to meteorological effects, especi...
- What is Tidal Window Calculation? The process of determining the optimal period based on tidal height during which a vessel can safely transit shallow wat...
- What is Topping Off? The final stage of tank filling during cargo loading, requiring slow rates and careful monitoring to prevent overfilling...
- What is Torrential Rain Advisory? An official advisory issued to warn of intense and prolonged rainfall that may severely reduce visibility and increase r...
- What is Torsional Shaft Vibration? Oscillation in the propulsion shaft caused by variations in torque, potentially leading to machinery damage if not contr...
- What is Track Made Good? The actual path a vessel follows over the ground, as recorded by position fixes, often used interchangeably with course ...
- What is Traffic Separation Scheme? An internationally recognized routing measure that separates opposing streams of vessel traffic by defined lanes and rul...
- What is Transverse Propeller Effect? Side-force generated by propeller rotation causing yaw, especially stern kick to port or starboard when powering ahead o...
- What is Transverse Thrust Correction? The adjustment applied to helm or engine orders to compensate for the sideways force exerted by a propeller, especially ...
- What is Tropical Storm Watch? An official advisory issued to warn vessels that a tropical storm may affect the area within 48 hours. Mariners should c...
- What is Tug Allocation Plan? A detailed arrangement indicating the number, type, and position of tugs assigned to assist a vessel during berthing, un...
- What is Tug Assistance Request? Formal VHF or written message from vessel or pilot to harbour authority asking for specified tug support for manoeuvring...
- What is Tug Lead Change? The coordinated operation in which a tug alters its line connection point or position to adapt to new towage requirement...
- What is Tug Line Tension? The force applied to a tow or mooring line connecting a tug to a vessel, monitored to ensure safe and effective manoeuvr...
- What is Turbocharger Maintenance? Scheduled inspection, cleaning, and servicing of the engine turbocharger to ensure optimal performance and prevent break...
- What is Turn Rate Predictor? ECDIS or radar-derived graphic that projects vessel’s future position based on present speed and rate of turn settings.
- What is Turning Bias Correction? The adjustment made to compensate for a vessel’s natural tendency to turn more easily in one direction due to hull desig...
- What is Turning Circle Diameter? The distance perpendicular to the original track between tangents of the vessel’s path when executing a steady-turn at a...
- What is Typhoon Warning? Highest-level tropical-cyclone warning issued by JMA or PAGASA for winds ≥64 kt, heavy seas and extreme storm surge thre...
U
- What is Ullage Hatch? A small tank opening used for manual ullage measurements and sampling of cargo on oil and chemical tankers.
- What is Ullage Survey? The process of measuring the empty space (ullage) in a cargo tank to determine the amount of liquid cargo loaded or rema...
- What is Under-Bridge Clearance? The vertical distance between the lowest part of the bridge span and the highest point of the vessel, ensuring safe pass...
- What is Underkeel Clearance? Vertical distance between the lowest point of a vessel’s keel and the seabed referenced to chart datum; the key safety m...
- What is Underkeel Margin Survey? Hydrographic assessment confirming minimum clearance between keel and seabed along planned passage meets safety criteria...
V
- What is Vapour Control? System and procedures used to contain, monitor, and safely manage vapours generated during loading or discharging of car...
- What is Vapour Emission? Release of vapours from cargo tanks or lines, controlled and monitored to prevent hazardous exposure, pollution, or brea...
- What is Vapour Lock? A condition where vapor forms in a pipeline or pump, blocking the flow of liquid cargo and potentially disrupting operat...
- What is Vapour Return? A pipeline or hose system connecting ship and shore to return displaced cargo vapours to the terminal during loading.
- What is Vapour Sampling? Procedure to collect representative samples of vapour from tanks or lines for safety, quality, or regulatory compliance ...
- What is Vapour Sampling? Procedure to collect samples of vapour from tanks or lines for safety, quality, or regulatory compliance testing.
- What is Vector Chart Display? An electronic navigational chart presented in vector format, enabling interactive layers and detailed, scalable map feat...
- What is Viscosity Control? The process of monitoring and adjusting the viscosity of liquid cargo, often by heating or blending, to ensure efficient...
- What is Viscous Flow Drag? The resistance experienced by a vessel as it moves through water due to the fluid’s internal friction, affecting speed a...
- What is VOC Control Procedure? Shipboard plan to minimise Volatile Organic Compound emissions during loading, voyage and discharge of crude oil cargoes...
- What is VTS Reporting Point? A specifically designated geographical position where a vessel is required to contact and report to the Vessel Traffic S...
W
- What is Warm Front Approach? Indication that a warm air mass front is advancing toward the vessel’s area, typically bringing steady rain and veering ...
- What is Water Cut? A measurement indicating the percentage of water present in a liquid cargo, essential for determining product quality an...
- What is Water Density Compensation? The adjustment made to vessel loading or draught calculations to account for local water density, affecting buoyancy and...
- What is Water Depth Alarm? An alert activated when the measured depth beneath a vessel approaches a pre-set minimum, used to avoid grounding.
- What is Waterjet Reversal Thrust? A manoeuvring action where the direction of waterjet propulsion is reversed, providing astern thrust for stopping or mov...
- What is Waterspout Risk Bulletin? An official maritime bulletin advising of the risk of waterspout formation in a specific sea area, requiring heightened ...
- What is Wave Height Advisory? A warning issued to vessels regarding anticipated significant wave heights exceeding safe operating limits.
- What is Waypoint Sequencing Alarm? An alarm on navigation systems indicating failure to automatically advance to the next waypoint as programmed in the voy...
- What is Wheel Over Alarm? An electronic or mechanical alarm that notifies the bridge team when it is time to initiate the wheel-over manoeuvre, us...
- What is Wheel Over Line? A track line shown on chart or radar which, when crossed, indicates the precise moment to start the wheel-over so that t...
- What is Wheel Over Point? The charted position at which the rudder is first applied to initiate a planned course alteration so that the vessel fol...
- What is Whiteout Condition Alert? A warning indicating that visual navigation is severely hindered due to uniformly diffuse light caused by snow, ice, or ...
- What is Winch Brake Holding? Certified static load that a mooring-winch brake can safely withstand without paying out when lines are under tension.
- What is Wind Direction Report? An official meteorological report or observation stating the current direction from which the wind is blowing, vital for...
- What is Windage Area Effect? The influence of the ship’s exposed surface area above the waterline, causing increased drift or leeway under wind press...
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