Glossary of maritime terminology

in shipping terms, BACAT stands for barge aboard catamaran. This is a vessel that transports barges which are loaded on and unloaded off, whilst it is floating. This is done by partially submerging the BACAT and loading the barges on via a gate in the BACAT's stern.

A Back-up Navigator is not an actual job but the name given to a member of the crew (usually an Officer) who has been assigned by the Master to be on call in the event that assistance is needed on the bridge.

A backhaul is when a vessel returns from her original destination to the original point of departure. 

A backstay is a long line or cable that runs from the rear of the vessel to the mast heads. Backstays help to support the mast.

Bagged cargo is any type of cargo that is normally packed in bags or sacks - such as cement, grain, flour, sugar, powdered milk etc.

The bale capacity is the total amount of space available for the carriage of bales, bags, pallets or boxed cargo, excluding the space between the frames and beams. The bale capacity is always slightly less than the grain capacity. 

Ballast is any solid or liquid weight that is brought on board a vessel in order to increase stability. For example if the cargo in one hold is heavy and the cargo in another hold is lighter ballast will be used to balance out the weight discrepancy. Ballast is also used if there are rough seas ahead or when the ship is empty of cargo. 

Ballast keel is a quantity of ballast which is secured by bolts to the keel to increase a boat’s stability.

If a cargo ship needs to sail without cargo, or with only a small quantity of cargo, it needs to travel in ballast. Generally this means carrying sea water in the ballast tanks to keep the vessel in trim and to ensure that the propeller and rudder are submerged. A ballast movement is the voyage, or leg of a voyage, spent under these conditions.

Ballast pumps are electrically-powered and used to pump water in and out of the ballast tanks when cargo is being loaded or unloaded.

A ballast system consists of ballast pumps and piping and enables water to be drawn from the sea or from a ballast tank and then discharged to another ballast tank or the sea. 

A ballast tank is a watertight compartment that is used for holding ballast water.

Ballasting is the process in which seawater ballast is pumped into ballast tanks to achieve a vessel’s desired stability, trim and draught.

A bareboat charter (also called a demise charter) is an agreement in which a vessel is chartered - or hired - without crew or provisions. The renter of the boat or ship takes care of these things themselves.

In freight terms, a barge is a flat-bottomed boat which is used to transport bulky cargo such as sand, coal, stone or lumber etc. by canal or river.

A barge aboard catamaran (BACAT) vessel transports barges which are loaded on and unloaded off, whilst it is floating. This is done by partially submerging the BACAT and loading the barges on via a gate in the BACAT's stern.

Barge carriers are ships that are designed to carry barges. The barge is loaded onto the carrier either by floating it on to the partially submerged carrier through a gate in the stern or by lifting it over the stern using a gantry crane. 

Battens, or cargo battens, are inserted into the hold of a cargo ship to keep cargo away from the vessel's sides in order to allow ventilation. 

In maritime terminology, a bay is a space on a cargo ship that is meant for holding containers. A container ship will have several bays, all of which are either under-deck (the hold) or on-deck. A numbering system enables ordered loading and unloading, with even numbered bays being suitable for 40-feet containers and odd numbered bays being for 20-foot containers.

BBB stands for before breaking bulk. It is an expression that means making freight payment before a shipment of goods is discharged. Under typical circumstances, freight is paid once the goods have been delivered, however, in the event of BBB, freight must be paid before the vessel is allowed to leave port.

BDN stands for Bunker Delivery Note -  a document which contains information pertaining to the delivery of fuel to a ship. This includes the vessel’s name, the port the bunkering took place at, the date, the amount and type of fuel, and the supplier’s information.

Also known as sea marks, seamarks and navigation marks, a beacon is an aid that is fixed to the shore (i.e. a lighthouse) or to the seabed to help navigators and pilots identify the approximate position of a maritime channel or hazard to allow them safe passage of their vessel.

Also called breadth, the beam is the width of a vessel.

Before breaking bulk is an expression that means making freight payment before a shipment of goods is discharged. Under typical circumstances, freight is paid once the goods have been delivered, however, in the event of Before breaking bulk (BBB), freight must be paid before the vessel is allowed to leave port.

The ship's bell is used to announce the time, as an alarm in the event of an emergency, and, its most common use these days, as a safety signal when the vessel is in foggy conditions. A bell usually has the ship’s name engraved on it and is most often made from bronze or brass. 

A bell buoy is a buoy that is fitted with a bell that sounds as the buoy moves with the motion of the sea.

1. Berth is a place assigned to a vessel when she is at anchor or is lying alongside a dock or pier etc.
2. A berth is also a bunk or bed on a ship.
   

Berthing is the act of approaching a port or harbor and securing the vessel in its assigned place - i.e. its berth.

A bight is a loop or bend in a rope.

A ship’s bilge is the lowest inner part, or the bottom part of the hull that would rest on the ground if the vessel was not supported by water. It encompasses the lower parts of the holds and machinery spaces and is designed to collect excess water.

Bilge blocks are used to support the bilge while the vessel is under construction or in dry-dock.

A bilge keel is a passive stability system that is used to reduce a vessel's tendency to roll. Bilge keels are used in pairs, one for the port side, and one for starboard. On rare occasions a ship may have more than one bilge keel per side.

A bilge pump is a water pump that is used to drain bilge water from a vessel. Many electric bilge pumps are fitted with float switches which activate the pump when the bilge fills to a specified water level 

The name given to water that collects in a vessel’s bilge. Bilge water is pumped out due its tendency to become foul smelling and putrid. Bilge water also contains other fluids such as those from internal drainage systems, machinery, sludge tanks and other sources. 

A bilge water separator, also often called an oily water separator is a piece of marine equipment that is used to separate oil and water. It separates oil from oily water so that only water is pumped into the ocean when bilge water is being discharged or when oil tanks are being cleaned.

A Bill of Lading (BL, B/L or BoL) is a legal document that is issued by or on behalf of a carrier detailing the type and quantity of goods being shipped, the shipper, the consignee, the ports of loading and discharge and the carrying vessel. It also acts as a receipt when the goods are delivered to their destination.

BIMCO is the Baltic and International Maritime Council, a commercial shipping trade organization and the largest international direct-membership organization for shipowners, shipbrokers, charterers and agents in the world.

In maritime terms, BL stands for Bill of Lading (also known as BoL or B/L.) It is a legal document that is issued by or on behalf of a carrier detailing the type and quantity of goods being shipped, the shipper, the consignee, the ports of loading and discharge and the carrying vessel. It also acts as a receipt when the goods are delivered to their destination.

An audible signal that is made with a ship’s whistle. A short blast is about one second long, while a prolonged blast lasts for between four and six seconds.

The blind sector is an area that cannot be scanned by a ship’s radar because the radar echoes are blocked by obstructions near the antenna, such as parts of the superstructure or the masts, etc.

The Blue Peter is a blue signal flag with a white square in the center. It is hoisted to indicate that a merchant ship is ready to sail.

BNWAS is short for Bridge Navigational Watch and Alarm System. Crucial in helping prevent accidents at sea, it is an alarm and monitoring system that alerts the ship’s master and other officers who are on navigational duties if the current Officer on Watch is unresponsive or not capable of responding or performing their watch duties satisfactorily.

In shipping terms, boarding arrangements or boarding facilities refer to the gear required for a pilot (and other personnel) to board a vessel such as pilot and accommodation ladders, gangways and ramps, mechanical hoists, and shell doors. 

Boarding facilities or boarding arrangements refer to the gear required for a pilot (and other personnel) to board a vessel such as pilot and accommodation ladders, gangways and ramps, mechanical hoists, and shell doors. 

Boarding speed is the speed of a vessel when it is adjusted to that of a pilot boat so that the pilot can safely embark.

Boat falls are the tackle used to lower or hoist a ship’s boat or lifeboat to or from the davits.

The Boatswain (often called the Bosun), is the highest unlicensed rating in the deck department. They are in direct charge of all deckhands and take their direct orders from the Chief Officer or Master. The Boatswain’s duties involve looking after the hull and deck of the vessel, making sure these parts of the ship, as well as her anchors, windlasses and other such equipment are well maintained and in good working order.

A Boatswain is also responsible for areas such as the Bosun’s store room, the paint locker, and the deck stores where the tools of their trade such as maintenance equipment, tools and supplies are kept.  

A boiler, in freight terms, is a unit that generates steam to propel a ship. Boilers are also used for onboard heating as well as other auxiliary purposes. 

BoL stands for Bill of Lading (also known as BL or B/L.) It is a legal document that is issued by or on behalf of a carrier detailing the type and quantity of goods being shipped, the shipper, the consignee, the ports of loading and discharge and the carrying vessel. It also acts as a receipt when the goods are delivered to their destination.

A bollard is found both on ships and on wharfs/docks. Generally speaking they are metal bases that are welded to the deck of a vessel or fastened to the dock, with two vertical bitts that are welded onto the sides to create a secure fastening for the mooring and berthing lines.

Bonded goods are products which must have duty paid on them which has not yet been paid. For example, goods that are in transit or in a warehouse waiting for clearance by customs.

A bonded warehouse is a storage facility where bonded goods (goods that are waiting for the duty to be paid on them) are stored. 

In maritime terminology, on a sailboat, a boom is a long spar (a pole) which runs along the foot of a fore and aft rigged sail. The boom’s main purpose is to make it easier to control the shape and angle of the sail and to ensure the foot is flatter when the sail angle is away from the centerline of the boat. The boom is tethered by a wire rope or tackle from aloft to its upper end, while its lower end is usually hinged and connected to the mast. 

Boottop, or bootopping (used by the merchant navy) is a thin strip of paint which runs around a vessel’s hull. Its purpose is to divide the anti-fouling paint which is below the waterline and the paint used on the topsides. It is usually a contrasting color to the two sections it is dividing. 

The boss hub, or propeller hub, is the central portion of a screw propeller to which the blades are attached and through which the propeller shaft end passes.

The Bosun (also sometimes called the Boatswain) is the highest unlicensed rating in the deck department. They are in direct charge of all deckhands and take their direct orders from the Chief Officer or Master. The Bosun’s duties involve looking after the hull and deck of the vessel, making sure these parts of the ship, as well as her anchors, windlasses and other such equipment are well maintained and in good working order.

A Bosun is also responsible for areas such as the Bosun’s store room, the paint locker, and the deck stores where the tools of their trade such as maintenance equipment, tools and supplies are kept.

The bosun store is a small space in which tools and small hardware items are kept so that the Bosun and his or her deckhands can efficiently carry out day to day repairs and maintenance.

The boundary layer is a narrow layer of moving water that is adjacent to a vessel’s hull as it travels through water.

The bow is the forward part of the hull of a ship or boat. Under normal circumstances, the bow will be pointing forward when the vessel is underway. 

Bow thrusters are propellers on the bow which are used as maneuvering aids for the vessel. They are extra propulsion devices and are located underwater and turn at right angles to the fore-and-aft line. They push the bow sideways in whichever direction they are employed and are usually used when mooring or docking. 

Box, in maritime terms, is a slang word for a shipping container.

Bravo stands for the letter B in the International Radiotelephony Spelling Alphabet, which is most often referred to as the NATO Phonetic Alphabet or simply the Phonetic Alphabet. This is the most commonly used group of code words used to clearly communicate the letters of the Roman alphabet, particularly over the radio and is essential in helping seafarers give and receive messages, orders and instructions clearly and correctly.

Also called beam, the breadth is the width of a vessel.

Break bulk cargo is loose cargo that is carried in drums, on pallets, in bags or in cartons etc. Break bulk or breakbulk cargo is stowed directly in the vessel’s hold, unlike bulk, containerized, or ro-ro cargo. It is carried by break bulk vessels, general cargo vessels, or multi-purpose vessels.

A break bulk vessel is a multi-purpose cargo ship designed for the transportation of break bulk cargo - i.e. cargo that is stowed in the vessel's hold in bags, cartons or on pallets

The bridge on a ship is a room or platform at the top of a vessel’s superstructure that operates as the command center. All communications and information goes through the bridge and it will be manned by an Officer of the Watch when the ship is underway. It has a clear view on all sides of the ocean and surrounding area. 

The bridge deck is the deck upon which a vessel's navigational equipment is housed.

The Bridge Navigational Watch and Alarm System (BNWAS) is crucial in helping prevent accidents at sea. It is an alarm and monitoring system that alerts the ship’s master and other officers who are on navigational duties if the current Officer on Watch is unresponsive or not capable of responding or performing their watch duties satisfactorily.

On some flying bridges there will be bridge wings which are narrow walkways / open areas that expand outwards over the sides of the vessel. These allow an Officer to see the side of the ship while docking, undocking, and working with smaller vessels such as when picking up or dropping off the pilot.

Broken stowage is the term given to ‘lost’ cargo space in a vessel’s holds due to a mismatch in the shape of the hull and the shape of the cargo. 

Bulk cargo is goods that are brought onboard the vessel in loose form and unpacked. For example, coal, coke, fertilizers, grain, iron ore, cement, phosphate, and minerals - basically anything that can be pumped or poured. The cargo is loaded directly into the ship’s holds. Ships that carry bulk cargo are known as bulk carriers or bulkers.

A bulk carrier, also called a bulker, is a vessel that has been designed to carry loose cargo that is directly loaded into the vessel with no packaging. Cargo can include coke, coal, grain, cement, iron ore, minerals or fertilizers.

A bulk container is a shipping container that has been specifically designed for carrying free-flowing dry cargo such as grain, coal, or cement. The cargo is poured into the container via openings in its roof and later discharged through other openings at the end of the container.

A bulkhead is an upright partition or wall in a ship’s hull which subdivides the vessel’s interior into watertight compartments. In the event of an accident, they reduce the extent to which the seawater can flood the ship, whilst also adding extra strength to the hull girder.

The bulkhead deck is the uppermost continuous deck of a ship to which all main transverse watertight bulkheads are carried.

The bulwark on a ship is a fore-and-aft vertical plating found directly above the upper edge of the vessel’s side surrounding the exposed deck or decks.

A bunk is a bed (or berth) in crew accommodation that is usually built into the cabin.

Bunker is the name given to the fuel (oil) used in ships. There are different types of ‘bunker’ and within those types there are also different standards, grades and classifications. For example: MDO (marine diesel oil), MGO (marine gas oil), MFO (marine fuel oil), HFO (heavy fuel oil) and IFO (intermediate fuel oil). Bunker can also refer to the tank or compartment that the fuel is stored in.

The Bunker Delivery Note (BDN) is a document which contains information pertaining to the delivery of fuel to a ship. This includes the vessel’s name, the port the bunkering took place at, the date, the amount and type of fuel, and the supplier’s information.

Bunkering or to bunker is the act of supplying a vessel with bunker - i.e. with filling its fuel tanks with fuel.

A bunkering vessel is a small tanker that is used to load fuel oils (bunker) into a ship’s tanks. It is equipped with fuel pumps and a crane for hose handling for this purpose.

A buoy is a seamark (or sea mark) - a floating object that is used as a navigational aid to help sailors identify the navigable limits of channels, their fairways, and sunken dangers such as rocks or shallow ground etc. They can also be used as a reference point for navigation or other reasons.

Also known as a buoy tender vessel or buoy laying vessel, a buoy layer is a boat that is used for handling, maintaining and replacing navigational buoys and beacons. Buoy Layer can also be used to refer to someone who does this for a living.

Also known as a buoy tender vessel or buoy layer, a buoy laying vessel is a boat that is used for handling, maintaining and replacing navigational buoys and beacons. Buoy Tender can also be used to refer to someone who does this for a living.

Also known as a buoy layer or buoy laying vessel, a buoy tender vessel is a boat that is used for handling, maintaining and replacing navigational buoys and beacons. Buoy Tender can also be used to refer to someone who does this for a living.

Buoyant smoke orange, also known as a buoyant smoke signal, falls under the category of life saving appliance and is a visual aid that draws attention to a boat or ship in distress. Buoyant smoke orange, as the name suggests, emit orange-colored smoke. They are useful at indicating the direction of wind and generally last for around three minutes.

A buoyant smoke signal, also known as buoyant smoke orange, falls under the category of life saving appliance and is a visual aid that draws attention to a boat or ship in distress. Buoyant smoke signals, as the name suggests, emit orange-colored smoke. They are useful at indicating the direction of wind and generally last for around three minutes.

A butterfly valve is a type of valve that is categorized as a quarter-turn valve due to it being fully open or closed when the disc is rotated a quarter turn. Commonly found on all different types of ships, butterfly valves are used for large capacity lines such lines from tanks to their pumps and as sea water suction lines.

Generally speaking, butterfly valves operate at lower pressures and temperatures than ball valves which can handle high temperatures and pressures.