Nautical and Navigational Terms

Aids to Navigation

• Lighthouses, navigation lights, buoys, and beacons constructed to assist in safe vessel navigation.

Almanac (Celestial Navigation)

• A periodic publication of variable astronomical information.

Anchorage

• An area designated for vessels to anchor or moor to a buoy.

Armament

• Weapons of a ship or aircraft.

Armor Belts

• Thick steel belts on old capital ship hulls protecting against shells and torpedoes.

Athwartships

• A crosswise direction on a vessel.

Atomic Time

• Time measured using an atomic clock, usually cesium-based. See also Coordinated Universal Time.

Barge

• Small craft transporting senior officers, or long, flat-bottomed craft towed for hauling cargo.

Battle Dressing Station

• First aid station for handling battle casualties.

Beacon

• Navigation aid with a tower or pile and a daymark, sometimes with a light, used instead of buoys.

Beam

• Extreme width of a ship or boat.

Bearing

• Direction of an object from an observer, measured clockwise from true north, magnetic north, or a vessel’s bow.

Bend (Knot)

• A knot used for joining two lines.

Berthing Compartment

• Living quarters for enlisted crew on a Navy ship.

Bilges

• Spaces between the inner and outer bottoms of a ship.

Bitts

• Deck fitting with two vertical metal cylinders for securing mooring lines.

Boat Etiquette

• Naval customs and traditions pertaining to small boats.

Boat Officer

• A junior officer in charge of a small boat under certain circumstances.

Bollard

• Large, cylindrical fitting on a pier for securing a ship's mooring lines.

Bowsprit

• A beam extending from a boat's bow supporting a platform called a pulpit.

Breast Line

• A mooring line perpendicular to a pier, controlling a vessel's distance from the pier.

Bridge

• Platform on a ship, submarine, or boat from which maneuvers are directed underway.

Building Dock

• A dry dock used for ship construction.

Building Ways

• Open construction area with blocks for building ships.

Bulkheads

• Inner walls of a vessel or naval installation on land.

Buoy

• Moored floating marker guiding vessels in navigable waterways.

Camel

• Floating wooden platform between a ship and a pier, used as a buffer or for maintenance.

Capstan

• Rotating drum of a winch for raising an anchor cable.

CAPTOR Mine

• Encapsulated homing torpedo mine activated by a ship or submarine's acoustic or magnetic signature.

Cardinal Buoyage System

• International system marking hazard positions or safe water directions.

Cardinal Compass Points

• North, south, east, and west.

Cartographers

• Map and chart makers.

Catamaran

• A twin-hulled vessel.

CBDR

• Constant bearing, decreasing range approach situation.

CBR Warfare

• Chemical, biological, or nuclear (radiological) warfare.

CCS

• Central control station, the main damage control center on newer ships.

Chain Locker

• Compartment for stowing a vessel's anchor chain.

Chain Pipe

• Pipe through which an anchor chain runs from deck to chain locker.

Chain Stopper

• Short chain with turnbuckle and pelican hook to hold an anchor chain in place.

Chartplotters

• Electronic navigational plotters displaying a vessel's plot on electronic charts.

Chock

• Metal fitting on a ship for mooring lines to pass through.

Class (of Ships)

• Ships built to the same design, named after the first ship built.

Cleat

• Anvil-shaped deck fitting for securing lines on a boat, ship, or pier.

Closest Point of Approach (CPA)

• Distance and bearing from a reference ship to a maneuvering ship at their closest approach.

COLREGS

• International Regulations for Preventing Collisions at Sea, governing vessel maneuvers in international waters.

Commissioning

• Formal placement of an officer or naval vessel on active government service.

Compass Rose

• Nautical chart graphic depicting true and magnetic bearing circles, showing variation angle and its annual change.

ConRep

• Connected replenishment of a ship at sea from another ship alongside.

Controllable-Pitch Propeller

• Ship propeller with adjustable blade pitch.

Coordinated Universal Time (UTC)

• Atomic time based on cesium vibrations, the world time standard since 1972.

Course

• True or magnetic direction a vessel is steered.

Coxswain

• Person in charge of a small powerboat or rowing shell.

Damage Control

• Measures to limit ship damage from enemy action, fire, flooding, and smoke.

Damage Control Assistant (DCA)

• Officer in charge of the damage control organization on a ship.

Date/Time Group

• Standardized format for referencing and filing military messages by originator, date, and UTC time.

Daybeacon

• An unlighted structural aid to navigation.

Daylight Saving Time

• Zone time advanced one hour, usually in summer.

Daymark

• Marker on a beacon indicating its purpose; conical top-mark on cardinal buoys indicating the direction of danger.

Day Shapes

• Geometric shapes displayed by vessels engaged in certain activities or in a special status.

DCC

• Damage control central, the main damage control center on older ships.

DCPO

• Damage control petty officer; typically assigned to each division on Navy ships.

Dead Reckoning

• Method of deducing a craft's position using courses and speeds since the last fix.

Depth Contours

• Hydrographic lines on a chart indicating areas of specific depths and shoals.

Depth Finder

• Another name for an echo sounder.

Designation (Ship)

• Letters and hull numbers identifying a ship.

Deviation

• Deflection between magnetic north and compass north due to iron metal.

Dividers

• Instrument for measuring distance on a nautical chart.

Dogs (Ship)

• Latches securing doors and hatches on a ship.

Draft

• Vertical depth of a vessel’s hull below the waterline.

Dry Dock

• Structure that can contain a ship and be drained to leave the ship dry.

ECDIS

• Electronic Chart Display and Information System, a GPS plotter accepted as a legal alternative to paper charts.

Echo Sounder

• Device measuring water depth by timing a sound pulse's round trip to the sea bottom.

ECN

• Standardized electronic navigational chart meeting IMO requirements for ECDIS use.

ECS

• Electronic Chart System plotter not certified as a legal equivalent to paper charts.

Eductor

• A jet-type dewatering pump.

Endurance

• Maximum time or distance a vessel can cruise at its most economical speed.

Equation of Time

• Difference between apparent time (actual Sun) and mean time (mean Sun).

Fantail

• The after part of the main deck of a vessel.

Fathometer

• Alternative name for a depth finder.

Fender

• Pneumatic rubber cylinder buffering a ship from a pier or another vessel.

Fid

• Tapered wooden tool for splicing fiber lines.

Fix

• Position determined by intersecting two or more lines of position.

Fog Signals

• Audible signals required by nautical rules when visibility is reduced.

Forecastle

• Forward part of the main deck.

Foremast

• Forward-most mast of a ship with multiple masts.

Frame (Ship Construction)

• Transverse girders running athwartships from a ship's keel.

Freeboard

• Distance from the waterline to the main deck of a ship's hull.

Galley

• The kitchen on a vessel.

Gig

• Ship’s boat designated for use by the commanding officer.

Give-Way Vessel

• Vessel required to maneuver to avoid another vessel.

Gnomonic Projection

• Chart projection where the globe is projected onto a tangent plane; great circles appear as straight lines.

GPS

• U.S. Global Positioning System using 31 satellites for accurate positioning.

Graving Dock

• Another name for an excavated dry dock.

Great Circle

• Circle formed by a plane through Earth's center; shortest distance between two points.

Greenwich Mean Time (GMT)

• Time based on the mean Sun relative to the prime meridian at Greenwich, England.

Ground Tackle

• Ship's anchors, anchor cable, and related handling gear.

GTE

• Gas turbine engine.

Gunwale

• Intersection of a ship's main deck and side plating.

Gyrocompass

• Electromechanical compass aligned with true north using a gyroscope.

Gyrocompass Repeater

• Remote gyrocompass readout duplicating the vessel's gyrocompass card.