Glossary - Nautical terms

A & a's

Alterations and additions to the structure, rigging and equipment of a warship.


A foresail when against the wind, used when tacking to help the vessel turn.


Toward the stern, relative to some object ("abaft the fore hatch"). Behind; as in: The stern is abaft the beam.

Abaft the beam

Further aft than the beam: a relative bearing of greater than 90 degrees from the bow: "two points abaft the beam, starboard side". That would describe "an object lying 22.5 degrees toward the rear of the ship, as measured clockwise from a perpendicular line from the right side, center, of the ship, toward the horizon."

Abandon ship!

An imperative to leave the vessel immediately, usually in the face of some imminent overwhelming danger. It is an order issued by the Master or a delegated person in command. (It must be a verbal order). It is usually the last resort after all other mitigating actions have failed or become impossible, and destruction or loss of the ship is imminent; and customarily followed by a command to "man the lifeboats" or life rafts.


Alongside or at right angles to the centerline of a boat. “The marine police brought their patrol boat just abeam of us.” On the beam, a relative bearing at right angles to the ship's keel. At a right angle to the boat; as in: That buoy lies abeam of us.

Able seaman

Also able-bodied seaman. A merchant seaman qualified to perform all routine duties, or a junior rank in some navies.


On or in a vessel. Synonymous with "on board." (See also close aboard.) On the boat; as in: If we go aboard the boat now we will be able to leave soon.


"To go about is to change the course of a ship by tacking. Ready about, or boutship, is the order to prepare for tacking."

Above board

On or above the deck, in plain view, not hiding anything. Pirates would hide their crews below decks, thereby creating the false impression that an encounter with another ship was a casual matter of chance.

Above-water hull

The hull section of a vessel above the waterline, the visible part of a ship. Also, topsides.

Absentee pennant

Special pennant flown to indicate absence of commanding officer, admiral, his chief of staff, or officer whose flag is flying (division, squadron, or flotilla commander).

Absolute bearing

The bearing of an object in relation to north. Either true bearing, using the geographical or true north, or magnetic bearing, using magnetic north. See also bearing and relative bearing.

Accommodation ladder

A portable flight of steps down a ship's side.

Accommodation ship (or accommodation hulk)

A ship or hulk used as housing, generally when there is a lack of quarters available ashore. An operational ship can be used, but more commonly a hulk modified for accommodation is used.

Act of pardon or act of grace

A letter from a state or power authorising action by a privateer. See also Letter of marque.

Action stations

See Battle stations.


Senior naval officer of Flag rank. In ascending order of seniority, Rear Admiral, Vice Admiral, Admiral and (until about 2001 when all UK five-star ranks were discontinued) Admiral of the Fleet (Royal Navy). Derivation Arabic, from Amir al-Bahr ("Ruler of the sea").


1. A high naval authority in charge of a state's Navy or a major territorial component. In the Royal Navy (UK) the Board of Admiralty, executing the office of the Lord High Admiral, promulgates Naval law in the form of Queen's (or King's) Regulations and Admiralty Instructions. 2. Admiralty law

Admiralty law

Body of law that deals with maritime cases. In the UK administered by the Probate, Divorce and Admiralty Division of the High Court of Justice or supreme court.


1. Afloat and unattached in any way to the shore or seabed, but not under way. When referring to a vessel, it implies that the vessel is not under control and therefore goes where the wind and current take her (loose from moorings or out of place). 2. Any gear not fastened down or put away properly. 3. Any person or thing that is misplaced or missing. When applied to a member of the navy or marine corps, such a person is "absent without leave" (AWOL) or, in US Navy and US Marine Corps terminology, is guilty of an "unauthorized absence" (UA). 4. No power, unsecured; as in: Without wind and no engine we would be adrift.

Advance note

A note for one month's wages issued to sailors on their signing a ship's articles.


See aviso.


Of a vessel which is floating freely (not aground or sunk). More generally of vessels in service ("the company has 10 ships afloat"). Floating, as in: Our life jackets will keep us afloat.


1. In, on, or toward the front of a vessel. 2. In front of a vessel.


Toward the stern of the boat, or closer to the stern than another item being referenced. “The captain’s chair is just aft of the helm station.” The portion of the vessel behind the middle area of the vessel. Towards the stern (of the vessel).


Toward the stern.

Aft and after

Direction; as in: Go aft to the stern of the boat.


1. On larger ships, a secondary gangway rigged in the area aft of midship. On some military vessels, such as US Naval vessels, enlisted personnel below E-7 board the ship at the afterbrow; officers and CPO/SCPO/MCPO board the ship at the brow.

Afternoon watch

The 1200–1600 watch.


Resting on or touching the ground or bottom (usually involuntarily).


(not to be confused with grounding at anchor). Stuck on the bottom; as in: That boat seems to have run aground.


Forward of the bow. In front of the boat; as in: Our destination lies ahead. aid to navigation (ATON). A buoy, channel marker, or light meant to guide navigation; as in: Be sure to look for any aid to navigation to help guide us into the harbor. An online reference is here:


A cry to draw attention. Term used to hail a boat or a ship, as "Boat ahoy!"


1. Lying broadside to the sea. 2. To ride out a storm with no sails and helm held to leeward.

Aid to navigation

1. (ATON) Any device external to a vessel or aircraft specifically intended to assist navigators in determining their position or safe course, or to warn them of dangers or obstructions to navigation. 2. (ATON) Any sort of marker which aids the traveler in navigation; the term is most commonly used to refer to nautical or aviation travel. Common types of such aids include lighthouses, buoys, fog signals, and day beacons.

Air-dried lumber

Lumber or other wood products that have been either dried by exposure to natural atmospheric conditions outdoors or in an unheated shed. Wood that is dried to equilibrium with the surrounding atmosphere. Moisture content of air-dried wood fiber depends on relative humidity, temperature, and length of drying period. Also referred to as air seasoned and contrasts with kiln-dried (KD) lumber.

Aircraft carrier

A warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Since 1918, the term generally has been limited to a warship with an extensive flight deck designed to operate conventional fixed-wing aircraft. Also called a flat top or a bird farm (US Navy).


1. On the lee side of a ship. 2. To leeward.

All hands

Entire ship's company, both officers and enlisted personnel.

All night in

Having no night watches.

All standing

Bringing a person or thing up short, that is an unforeseen and sudden stop.


A term used in maritime law – To impact a stationary object (not submerged), such as a bridge abutment or dolphin, pier or wharf, or another vessel made fast to a pier or wharf. More than incidental contact is required. The vessel is said to "allide" with the fixed object and is considered at fault. As opposed to collision.


In the rigging of a sailing ship. Above the ship's uppermost solid structure; overhead or high above. Above the deck, generally in the rigging. “Harry went aloft to fix the VHF antenna.” Up in the rigging; as in: Our radar reflectors are aloft. 1. In the rigging of a sailing ship. 2. Above the ship's uppermost solid structure. 3. Overhead or high above.


By the side of a ship or pier.

Altocumulus clouds

Forming discernable globs, may appear in layers; as in: Altocumulus clouds usually promise rain soon.


The central portion of the boat. “Let’s keep all the crew amidships to balance the boat better.” The middle section of a vessel with reference to the athwartships plane, as distinguished from port or starboard ("Put your rudder amidships." (Compare Midships.)). In the middle of the boat; as in: You will find the galley amidships.

Amine blush

Most epoxies used in boatbuilding have "amine"-based hardeners. After the epoxy is cured there will usually be a noticeable oily residue on the surface called amine blush. The amount of amine blush can vary considerably, from almost unnoticeable to very oily. This difference is the result of differences in temperature and humidity. The amine blush can affect the bond of subsequent coats of epoxy or paints and should be removed. Although a variety of solvents have been used to remove amine blush, in the shop we use denatured alcohol (shellac thinner), laquer thinner or acetone. Amine blush can be sanded off, but will require a lot of sandpaper as the paper tends to clog quickly.


A device, usually deployed from the bow, used to secure the boat to the bottom; as in: The use of more than one anchor will limit swing room. 1. an object designed to prevent or slow the drift of a ship, attached to the ship by a line or chain; typically a metal, hook-like or plough-like object designed to grip the bottom under the body of water (but see also sea anchor). 2. to deploy an anchor ("She anchored offshore.")

Anchor ball

Round black shape hoisted in the forepart of a vessel to show that it is anchored.