Human, Cultural, Historical and Reference

The Reference Layer: Glossary, Units, Signals and Information Sources glossary

The connective tissue of the field: the maritime glossary anchored by the IMO SMCP and the IHO Hydrographic Dictionary S-32, units at sea (the nautical mile, knot, the four tonnage measures, the sverdrup, the decibel re one micropascal), the International Code of Signals and flag etiquette, lighthouses and aids to navigation, traditional seamanship craft, ship’s documents, maritime media and data providers, and the standard scales (Beaufort, Douglas).

260 defined terms.

Showing 250 on this page (page 1 of 2).

A

Abaft: Toward the stern of a vessel.
Abeam: Bearing 090° relative to ship's heading.
Above-Water Hull: Portion of the hull above the waterline.
Adrift: Floating without control.
Aft: Toward the stern.
Aground: Resting on the bottom.
Alfa Flag: Letter A of the International Code of Signals, meaning "I have a diver down, keep well clear at slow speed."
All Hands: Entire ship's crew.
Almanac (Nautical): Annual ephemeris tables for celestial navigation.
Anemometer: Instrument for measuring wind speed.

B

Backstay: Standing rigging supporting a mast from aft.
Ballast: Weight low in the vessel used to enhance stability.
Baltic Capesize Index (BCI): Capesize segment of the Baltic indices.
Baltic Dry Index (BDI): Composite dry-bulk freight index published by the Baltic Exchange.
Baltic Exchange: London-based provider of freight market information and assessments.
Baltic Panamax Index (BPI): Panamax segment of the Baltic indices.
Baltic Supramax Index (BSI): Supramax segment of the Baltic indices.
Bearing: Direction to an object from the observer.
Beaufort scale: Empirical wind force scale 0-12.
Bowline: Knot forming a non-slipping loop at the end of a line.

C

Cable: Unit of length of one-tenth of a nautical mile, 185.2 m.
Capesize: Bulker >150,000 DWT too large for Suez/Panama traditionally.
Cargo Manifest: Statutory list of cargo carried.
Certificate of Registry: Ship's document evidencing flag registration.
Charlie Flag: International Code of Signals letter C, meaning "Yes" (affirmative).
Charterparty: Contract for hire of a vessel; main types are voyage, time, bareboat, and slot.
Clarksons: London-based shipbroker and shipping data provider, founded 1852.
Class certificate: Document confirming the vessel's classification status.
Cleat Hitch: Standard knot for securing a line to a cleat.
Compass Card: Graduated card of the magnetic compass.

D

Deadweight Tonnage (DWT): Maximum mass of cargo, fuel, stores, water, and crew a vessel can carry.
Decibel re 1 micropascal: Standard reference for underwater sound pressure level.
Deck log: Official bridge log book.
Delta Flag: International Code of Signals letter D, meaning "Keep clear of me; I am maneuvering with difficulty."
Displacement Tonnage: Total mass of water displaced by a vessel.
Distance Log: Instrument recording distance run through the water.
DOC, Document of Compliance: ISM Code certificate issued to a shipping company.
Douglas Sea State Scale: Sea-state scale developed by Sir Henry Percy Douglas in 1917.
Draft Marks: Numbers on the bow, midship, and stern showing draft.
Dragging Anchor: Anchor failing to hold; vessel drifting under chain pull.

E

Echo Flag: International Code of Signals letter E, meaning "I am altering course to starboard."
Echo sounder: Acoustic depth sensor.
Ensign: National maritime flag flown from the stern.
Ephemeris: Tabulated celestial positions.
Equasis: Free online ship-information database operated by EMSA and partners.
Equation of time: Difference between mean and apparent solar time.
Equator Crossing Certificate: Traditional document issued to seafarers crossing the line.
Ericson Light: Range light navigation aid manufacturer reference.
Estimated Time of Arrival (ETA): Predicted time of arrival.
Estimated Time of Departure (ETD): Predicted departure time from a port.

F

Fathom: Unit of depth of 6 feet, 1.8288 m.
Fender: Energy absorbing system at berth, designed per PIANC WG211 (formerly WG33).
Figure-of-Eight Knot: Stopper knot at the end of a line.
Fix: Determined geographical position.
Flag State: State of the ship's nationality, with jurisdiction under UNCLOS Article 94.
Flemish Coil: Decorative deck coil of a line.
Float Plan: Recreational passage plan filed with shore contacts.
Foghorn: Audible signal device under COLREGs.
Formal Safety Assessment: IMO risk-based decision-making methodology.
Foxtrot Flag: International Code of Signals letter F, meaning "I am disabled; communicate with me."

G

Galaxy of Bridge Equipment: Generic reference to integrated bridge systems.
Gangway: Movable ramp or bridge for boarding.
Garbage Record Book: Required under MARPOL Annex V Regulation 10.
GMDSS: Global Maritime Distress and Safety System under SOLAS Chapter IV.
Golf Flag: International Code of Signals letter G, meaning "I require a pilot."
GPS: Global Positioning System, US satellite navigation system.
Great circle: Circle on a sphere passing through the center.
Gross tonnage (GT): Volumetric measure per ITC 1969 GT = K1*V.
Gunter Rig: Sliding-topmast fore-and-aft rig.
Gyro Compass: North-seeking compass based on gyroscopic precession.

H

Half-hitch: Simple knot used as the basis of many compound knots.
Hand Lead: Sounding lead historically used to measure depth.
Hatch: Opening in a deck for cargo access.
Hawse: Area at the bow where anchors are stowed and chains lead.
Heading: Direction in which a vessel's bow is pointing.
Heave-to: Maneuver to hold position in heavy weather.
Helm Orders: Standard wheel commands such as "starboard 10."
High Water: Highest tidal level reached.
Hotel Flag: International Code of Signals letter H, meaning "I have a pilot on board."
Hydrographic Chart: Nautical chart produced by a hydrographic office.

I

IALA Maritime Buoyage System: Combined IALA A and IALA B regions.
IHO S-101: Next-generation ENC specification.
IHO S-32: International Hydrographic Organization hydrographic dictionary.
IHO S-57: ENC product specification, edition 3.1.
India Flag: International Code of Signals letter I, meaning "I am altering my course to port."
International Code of Signals: Referenced under SOLAS V/21.
International Hydrographic Organization (IHO): Intergovernmental hydrographic body based in Monaco.
International Load Line Certificate: SOLAS-related freeboard certificate.
International Sea Lanes: Recognized customary routes such as the Dover Strait TSS.
ITC69: International Convention on Tonnage Measurement of Ships 1969.

J

Jacobs Ladder: Rope or wire ladder used for boarding pilots and others.
Jib Halyard: Halyard for the jib.
Joining Bunkers: Maritime trade reference for fuel taken at a join port.
Joint Hull Committee: Lloyd's market underwriter committee for hull insurance.
Joule Reference Standard: SI energy unit used in marine engineering.
Juliet Flag: International Code of Signals letter J, meaning "I am on fire and have dangerous cargo on board; keep clear."
Jumbo Derrick: Heavy-lift derrick on a multipurpose vessel.
Jury Rig: Temporary improvised rig set after damage.
Justice of the Peace, Maritime Declarations: Historical UK affidavit jurisdiction.
JWC Listed Areas: Geographic zones triggering hull war additional premium.

K

Kelvin Wake: Characteristic wave pattern of a moving vessel.
Kentledge: Pig-iron permanent ballast.
Kilo Flag: International Code of Signals letter K, meaning "I wish to communicate with you."
King Plank: Center plank of a wooden deck.
Klaxon: Electric audible signaling device.
Knot: One nautical mile per hour.
Knot, Bowline: Standard non-slipping loop knot.
Knot, Clove Hitch: Two-half-hitch hitch used for securing a line to a spar.
Knot, Reef: Square knot used for reefing sails.
Knot, Sheet Bend: Knot for joining two lines of unequal size.

L

Lateral Mark: Channel-edge buoy or beacon under the IALA system.
Latitude: Angular distance north or south of the equator.
Lead Line: Traditional weighted line for taking soundings.
Lee Shore: Shore onto which the wind is blowing; hazardous in heavy weather.
Lighthouse: Tower with a navigational light.
Lima Flag: International Code of Signals letter L, meaning "You should stop your vessel instantly."
Lloyd's List: Maritime trade newspaper, founded 1734.
Lloyd's Register of Ships: Annual reference of merchant ships first published 1764.
Log Book: Statutory ship's record.
Longitude: Angular distance east or west of the prime meridian.

M

Magnetic compass: Standard magnetic compass per ISO 449.
Magnetic variation: Angle between true and magnetic north at a location.
Mark, Cardinal: IALA buoy indicating north, east, south, or west of the danger.
Marlinspike: Pointed iron tool for splicing rope.
Mast Light: All-round white masthead navigation light under COLREGs.
Maydays: Voice distress signal repeated three times on VHF channel 16.
Meridian: Great circle through both geographic poles.
Mike Flag: International Code of Signals letter M, meaning "My vessel is stopped and making no way through the water."
Mile, Nautical: 1852 m exactly by international agreement.
Morse Code: Dot-and-dash code used in flashing-light signaling.

N

National Ensign: National flag flown by a ship at sea.
Nautical Almanac: Annual joint UK/US publication.
Nautical mile: 1852 m international nautical mile.
Nautilus International: Officer-grade UK and Dutch seafarer trade union.
Navigation Lights: COLREGs Rule 21 to 31 lights.
Net tonnage (NT): Volumetric earning-capacity tonnage per ITC 1969.
NOTAM, Notice to Airmen: Aviation notice with maritime aviation overlap.
Notice to Mariners (NM): Periodical chart correction publication.
November Flag: International Code of Signals letter N, meaning "No" (negative).
Number Pennants: ICS numeric pennants 0 to 9.

O

Ocean Pilot Charts: Climatological pilot charts published by NGA.
Officer of the Watch (OOW): STCW certified navigation watchkeeper.
Oilskins: Waterproof outerwear traditionally worn by sailors.
One Long Blast: COLREGs sound signal indicating approach to a blind bend.
Operations Manual: Statutory ISM-mandated documentation onboard.
Orion Belt Stars: Navigation reference stars used in celestial navigation.
Oscar Flag: International Code of Signals letter O, meaning "Man overboard."
Out of Trim: Cargo or trim imbalance condition.
Outboard: Outside or away from the centerline.
Overhang: Portion of hull outside the perpendiculars.

P

Pagans, Code of: Historic reference to non-statutory maritime customs.
Panama Tonnage: Vessel tonnage measured for canal toll calculation.
Papa Flag: International Code of Signals letter P, the Blue Peter, meaning "All persons should report on board; vessel is about to proceed to sea" in harbor.
Parallel Index: Radar collision-avoidance technique.
Passage plan: Berth to berth voyage plan under SOLAS Chapter V.
Pilot Ladder: Ladder constructed to SOLAS V/23 standards.
Pilotage Exemption Certificate (PEC): Master's qualification to dispense with compulsory pilotage.
Plimsoll Line: Load-line mark on the hull side, named after Samuel Plimsoll.
Port: Left-hand side of a vessel when facing forward; also a harbor.
Position Report: Periodic report of position to traffic services or owners.

Q

QC, Quality Control: ISM-related shipboard quality control.
Qhse Document: Quality, Health, Safety, Environment shipboard documentation.
Quarantine flag: Yellow Q flag indicating request for free pratique.
Quartermaster: Helmsman on watch.
Quay: Solid berthing structure parallel to the shore.
Quay Crane: Container terminal ship-to-shore crane.
Quebec Flag: International Code of Signals letter Q, meaning "My vessel is healthy and I request free pratique."
Quick-Closing Valve: Engine-room safety valve required by SOLAS.
Quintant: Reflecting instrument with 144-degree arc.
Quote, Freight: Indicative shipping rate.

R

Radar: Radio detection and ranging device required by SOLAS V/19.
Radar Reflector: Passive device enhancing radar return.
Range light: Two fixed lights in line indicating channel.
Reef Knot: Square knot for reefing or tying small lines.
Reefing: Reducing sail area in heavy weather.
Repair specification: Owner-issued repair scope document.
Romeo Flag: International Code of Signals letter R.
Romeo Foxtrot Flag: Two-letter group; many ICS combinations.
Rotterdam Maritime Capital Reference: Generic example of maritime reference data.
Rule of the Road: Common term for the COLREGs.

S

Safety Management Certificate (SMC): Issued to ships under ISM Code.
Saffir-Simpson Hurricane Wind Scale: Five-category Atlantic hurricane intensity scale.
Sea State: Description of the wave field, characterized by significant wave height and period.
SECA, Sulphur Emission Control Area: MARPOL Annex VI designated low-sulfur area.
Semaphore: Hand-flag visual signaling system using letters.
Sextant: Marine sextant with vernier or micrometer.
Sheet: Line controlling the angle of a sail.
Sierra Flag: International Code of Signals letter S, meaning "I am operating astern propulsion."
SMCP: IMO Standard Marine Communication Phrases, adopted 2001.
Sverdrup: Unit of ocean volume transport, 1 Sv equals 10^6 cubic meters per second.

T

Tackle: Combination of blocks and line giving mechanical advantage.
Tango Flag: International Code of Signals letter T, meaning "Keep clear of me; I am engaged in pair trawling."
Tare Weight: Weight of an empty container or vessel.
Telegraph: Engine order communication device between bridge and engine room.
Thermohaline Reference: Oceanographic data reference used in routing.
Tonne: Metric ton of 1000 kilograms.
TradeWinds: International shipping newspaper published by NHST since 1990.
Traffic Separation Scheme (TSS): Routeing measure per Ships' Routeing.
Trinity House: General Lighthouse Authority and deep-sea pilotage body, chartered 1514.
Twenty-Foot Equivalent Unit (TEU): Standard container capacity unit.

U

UKC (Under Keel Clearance): Vertical distance keel-to-seabed.
UNCTAD Review of Maritime Transport: Annual UN reference publication.
Uniform Flag: International Code of Signals letter U, meaning "You are running into danger."
United Kingdom Hydrographic Office (UKHO): National hydrographic office, publisher of Admiralty Charts.
United States Coast Pilot: NOAA narrative supplement to nautical charts.
Universal Time Coordinated (UTC): Reference timescale for navigation.
Unmoor: Procedure to weigh both anchors and prepare to leave anchorage.
Up-and-Down Anchor: Anchor cable vertical, indicating anchor about to be tripped.
Upstream Vessel: Vessel proceeding against the current.
Used Bunker Certificate: Bunker delivery note (BDN) under MARPOL Annex VI.

V

Variation: See magnetic variation; difference between true and magnetic north.
Variation Diagram: Annual chart of magnetic isogonic lines.
Vector Chart: Layered digital chart used in ECDIS.
Vessel Monitoring System (VMS): Satellite tracking of fishing vessels.
Vessel Traffic Service (VTS): Shore-based service for monitoring port and waterway traffic.
VHF Marine Band: 156 to 174 MHz radio band used for maritime communications.
Victor Flag: International Code of Signals letter V, meaning "I require assistance."
VLCC: Very Large Crude Carrier, 200,000-320,000 DWT.
Voyage Data Recorder (VDR): SOLAS V/20 black-box equivalent for ships.
Voyage Plan: Required under SOLAS V/34.

W

Wake: Disturbed water astern of a moving vessel.
Watch System: Traditional four-on, eight-off three-watch or two-watch system, with the dog watch from 1600 to 2000 divided into two two-hour watches.
Waypoint: Programmed position on a passage plan.
Weather Helm: Tendency of a sailing vessel to head into the wind.
Whisker Flag: ICS double-letter signal variation reference.
Whiskey Flag: International Code of Signals letter W, meaning "I require medical assistance."
Wind Rose: Compass-rose diagram of wind direction frequencies.
WMO: World Meteorological Organization, the UN agency for weather, climate, and water.
World Geodetic System 1984 (WGS84): Standard geodetic datum used in GPS.
Wreck Marking Buoy: Emergency buoy marking a new danger under IALA.

X

X-band radar: 9.4 GHz band marine radar.
X-Marker, IALA Special: Yellow X-topmark special mark.
X-Ray Diffraction in Hull Surveys: Materials-test method.
X-Reference Notation: Generic chart cross-reference symbol.
X-Y Plotter: Historical chart plotting device used in hydrography.
Xenia Maritime Code: Generic example of regional maritime reference.
Xenon Flashing Light: High-intensity navigation aid lamp.
Xenon Strobe Light: High-intensity strobe used on liferaft locator lights.
Xerox Chart Folio: Historic copy-based chart management.
Xray Flag: International Code of Signals letter X, meaning "Stop carrying out your intentions and watch for my signals."

Y

Y-Splice Eye: Rope splice technique.
Yankee Flag: International Code of Signals letter Y, meaning "I am dragging my anchor."
Yard: Spar set crosswise from a mast carrying a square sail.
Yard-Long Splice: Long rope splice for running rigging.
Yardarm: Outer end of a yard.
Yardstick Handicap (RYA Portsmouth Yardstick): Dinghy handicap system in the UK.
Yaw: Rotational motion about the vertical axis.
Yellow Flag: Q quarantine flag flown to request pratique.
Yokohama Fender: Pneumatic ship-to-ship transfer fender developed by Yokohama Rubber.
Yon-Spotted Light: Generic reference to multi-character flashing aid.

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