Glossary of maritime terminology

An S&T heat exchanger is crucial for the efficient functioning of a number of different systems on a ship including the propulsion plant, auxiliary power generation system, starting air system, fuel injection system, AC system, fresh water system and the refrigeration system.

Also known as a shell and tube heat exchanger, this is a device in which two fluids circulate at different temperatures - one through the tubes within the shell and the other fluid in the shell itself. This action transfers heat between the two fluids.

Salvage is used to describe a vessel that has been recovered after being shipwrecked or the contents of the vessel herself.

The sanitary system on a ship, also called the domestic seawater system, is a system that is primarily used to flush the toilets onboard. The system is made up of a hydrophore tank - a compressed  air pressurized tank - that stores and pumps seawater through the toilets.

SAR stands for Search and Rescue and refers to an operation to supply assistance to a person or people in distress at sea regardless of their nationality, their status, or the circumstances in which they are found. SAR must adhere to the applicable Maritime Law and Conventions.

In shipping terms, a ship’s satellite communication system is used to transmit and receive signals when the vessel is out of the coverage area of shore-based stations. The artificial communications satellite transmits these signals via a transponder by creating a channel between the transmitter and the receiver at different locations. 

A satellite speed log is an instrument used to measure the speed of a ship, however unlike most other speed logs it records the speed over the ground as opposed to through the water. Highly accurate, satellite logs work on GPS signals and, thanks to their accuracy, they are often used for docking and undocking vessels. These logs also measure the forward and aft speeds of the ship along with the athwartships speed.

SCBA stands for self-contained breathing apparatus. On a ship, this protects the wearer from gasses, vapors, dust and oxygen deficiency. Most self-contained breathing apparatus used on vessels are the open circuit type in which air from the one or two pressurized cylinders is for inhalation while the exhaled air is released into the atmosphere. All vessels that have ammonia as a refrigerant onboard must be equipped with a minimum of two SCBAs. 

SCR stands for Selective Catalytic Reduction. It is a system that uses a chemical reaction (catalyst elements and a reducing agent) to reduce the level of nitrogen oxide (NOx) in a vessel’s exhaust gas from the engine. During this process, a reducing agent of an urea water solution is added to the exhaust gas stream.

Also known as a seamark, beacon and navigation mark, a sea mark 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.

Sea trials are a series of tests carried out by shipbuilders on a new vessel whilst the shipowner's representatives are on board to check that the ship has met the owners specifications.

A seafarer is anyone who is employed to work on a seagoing boat or vessel. This includes everyone from the Master (Captain) of the ship through to Officers, crew, Deck Cadets and also people employed as entertainers, carpenters, stewards and retail staff on cruise or passenger ships.

A seafarer app is a mobile application that lets seafarers find and apply for jobs at sea online, and follow up applications and communicate with employers and manning agents, all through their mobile device no matter where in the world they are.

A seafarer job is any kind of role performed working on a seagoing boat or vessel. This includes everything from Master (Captain) jobs through to Officer jobs, crew jobs, Deck Cadet jobs and also positions such as entertainment, carpentry, steward and retail jobs on cruise or passenger ships.

A seafarer resume or seafarer CV is a document given to prospective employers and manning agents that lists a seafarer's certifications and documentation, as well as their skills and proficiency in the English language. 

A seafarer training provider in the maritime industry is a company who supplies shipping companies with the training and education needed for their seafarers. For example, they may run courses on how to handle new equipment or technologies.

Seafarer training providers can connect with these shipping companies by adding their details to an online maritime directory or crewing marketplace website so that those in need of their services can more easily find what they are looking for.

Also known as a sea mark, beacon and navigation mark, a seamark 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.

Search and Rescue (SAR) refers to an operation to supply assistance to a person or people in distress at sea regardless of their nationality, their status, or the circumstances in which they are found. SAR must adhere to the applicable Maritime Law and Conventions.

Seaspeak is the name given to the language seafarers use at sea. It combines English language with specific maritime terms and commands (for example, starboard instead of right or aft, meaning towards the rear of the vessel). It is used so that seafarers of different native languages can communicate with one another safely and efficiently. A certain level of proficiency in the English language is required by most reputable shipping companies. Seaspeak is also known as Maritime English and Standard Marine Communication Phrases or SMCP.

Seaworthiness is the ship’s condition in respect of its construction, condition, equipment and even crew with regards to the manner in which it is to be used. If any aspect of a vessel is in disrepair, damaged or ill maintained, or if the crew is deemed to be insufficient to handle the ship and her cargo, the vessel may be considered unseaworthy and unable to sail.

A Seaworthiness Certificate is a document issued by a surveyor that allows a ship to sail after an incident or situation has occurred where seaworthiness was affected. Often a certificate is issued once temporary repairs have been carried out so that the ship may sail to another port or to a dry dock where permanent repairs can be made.

The Second Dog Watch is the period of being on duty (AKA watch) that takes place onboard a vessel between 1800hrs and 2000hrs. It is 2 hours shorter than the usual four hour watches as it is split into First Dog Watch and Second Dog Watch so that those on duty may eat their evening meal.

The Second Engineer is next in line of command to the Chief Engineer. It's a maritime job with a lot of responsibility and the 2E will spend their days assisting the CE in managing the engine room with a sharp eye on efficiency and safety. They supervise the daily maintenance and operation of the engine department and should the Chief Engineer be unable to perform their duties, the Second Engineer will step into their place.

Secondary clocks, also known as slave clocks, are the timepieces that are located throughout a vessel. It is crucial that they all display the exact same time and this is ensured by having them controlled by a master clock - also known as a main clock - which transmits signals or control pulses to the secondary clocks that are connected to it.

The seismic survey vessel is a ship that maps out geological features in the seabed so that the optimal location for drilling for oil or gas in the oceans can be pinpointed. This is achieved by  firing air guns that transmit sound waves into the bottom of the sea. The shot’s echo is then captured by hydrophones - microphones specifically designed for underwater use - that are towed behind the vessel. 

A Selective Catalytic Reduction (SCR) system uses a chemical reaction (catalyst elements and a reducing agent) to reduce the level of nitrogen oxide (NOx) in a vessel’s exhaust gas from the engine. During this process, a reducing agent of an urea water solution is added to the exhaust gas stream.

A self-contained breathing apparatus (SCBA) on a ship protects the wearer from gasses, vapors, dust and oxygen deficiency. Most self-contained breathing apparatus used on ships are the open circuit type in which air from the one or two pressurized cylinders is for inhalation while the exhaled air is released into the atmosphere. All vessels that have ammonia as a refrigerant onboard must be equipped with a minimum of two SCBAs. 

Also known as a self-unloading vessel or a geared vessel, a self-geared vessel is a ship that has its own onboard gear - i.e. cranes. This means that the vessel can load and unload cargo, including containers, without portside assistance thus making the vessel more versatile as it can dock in more ports.

A self-trimming ship is a vessel with a hold that is designed in such a way that the cargo levels itself when in transit.

Also known as a geared vessel or a self-geared ship, in freight terms, a self-unloading vessel is a ship that has its own onboard gear - i.e. cranes. This means that the vessel can load and unload cargo, including containers, without portside assistance thus making the vessel more versatile as it can dock in more ports.

A semi-submersible rig is a floating offshore drilling platform that has submerged pontoons to give it stability.

A semi submersible vessel is a ship that is able to submerge part of itself to load or discharge cargo (i.e. another vessel) that can be floated on or off. The majority of semi submersible vessels are heavy lift ships or heavy load vessels however they may also be used to drill for gas and oil in deep waters.

A sewage treatment plant on a ship, also called a marine sewage plant, is used to treat wastewater on the vessel so that it can either be reused or returned to the ocean. It is crucial that the rules and regulations surrounding the treatment of marine wastewater are followed as any reused water must be safe and returned water must have minimal environmental impact.

Sheddage is the fee a vessel is charged for using shed space at a terminal. The charge is based upon the length of the vessel regardless of the time they spend there.

In maritime terms, a shell and tube heat exchanger is crucial for the efficient functioning of a number of different systems on a ship including the propulsion plant, auxiliary power generation system, starting air system, fuel injection system, AC system, fresh water system and the refrigeration system.

Also known as an S&T heat exchanger, this is a device in which two fluids circulate at different temperatures - one through the tubes within the shell and the other fluid in the shell itself. This action transfers heat between the two fluids.

When cargo in the hold, or loaded onto a ship, moves, shifts or changes position it is known as shifting. This is a dangerous situation as the vessel can become unbalanced and containers could potentially end up falling into the sea.

A ship log, also sometimes referred to as a speed log, common log or chip log, is an instrument which is used to measure a ship’s speed and the distance it has traveled. The speed is determined by referencing the water flowing past the hull (water reference speed) or by the seabed (ground reference speed).

There are five different types of ship log which all work on different principles: the electromagnetic ship log, the pitometer ship log, the doppler ship log, the impeller ship log and the satellite ship log. See their individual glossary entries for more information on each.

A ship toilet, also called a marine toilet or vacuum toilet, is used on boats and ships of all types and sizes. Ship toilets work by removing the waste from the bowl by suction and then depositing it in a holding tank when the toilet is flushed. Traditional toilets, such as those found in the home, use a combination of water and gravity to transport the waste from the bowl to a collection or treatment tank.

Like regular toilets, ship toilets use water to flush although in far smaller quantities - typically around 1.5 liters of water per flush as opposed to the 10 liters used by a non-vacuum toilet.

The Ship’s Articles or, to give it its full title, the Ship’s Articles of Agreement, is the employment contract between the Master of a ship and a crew member. The document includes the date the voyage will commence, the contract’s duration, the salary and the rank of the seafarer.

A Ship's Carpenter may be involved in actually building vessels or they could work in repair and maintenance. There are both shore-based maritime jobs available for carpenters, as well as offshore jobs on cargo ships and cruise ships.

The Ship’s Cook is responsible for keeping the crew well fed and fueled with enough energy to carry out their strenuous and often physically demanding jobs. On a merchant vessel they will normally be the only member of the Steward Department, however on a passenger ship the galley (kitchen) will be fully staffed with a Chief Cook and their assistant Cooks as well as Pastry Chefs and Sous Chefs, if the vessel is a cruise ship.

A Ship’s Electrician is specially trained to work with all three aspects of their job: electricity, water, and of course vessels. The Electrician will need to read, and understand, various technical diagrams, manuals and documentation. They will be installing, inspecting, repairing and replacing electrical components and wiring. They will also be responsible for the repair and maintenance of electrical systems and equipment on board the vessel.

A Marine Electrician may also be responsible for upgrading components, systems or equipment, and they will regularly use testing and measuring tools such as ohmmeters, oscilloscopes and voltmeters to run diagnostics and check everything is in good working order. If not, repair, or perhaps replacement of parts or systems will be necessary.

A Ship's Plumber job consists of maintenance and repair to make sure that plumbing throughout the ship is in good working order. This includes the toilet, sewer and drainage systems. They will handle the hoses when potable water is being loaded onto the vessel and maintain potable water systems. The ship’s blackwater and greywater plant systems must be looked after too. On a cruise ship the Ship's Plumber will also maintain and repair swimming pool and environmental systems where needed and respond to passenger complaints regarding the water supply / plumbing.

A Shipfitter or Ship Fitter is a maritime job. Shipfitter jobs are exactly what they sound like: the job entails fitting the parts of a ship together. A Shipfitter’s duties include following blueprints to accurately cut and attach the enormous sheets of structural metal that are fitted together to create a vessel’s hull. The bulk of a Shipfitter job entails the fabrication, assembly and erection of a ship’s main structure and parts, but it also includes the maintenance, repair and restoration of the same.

A shipping agent is a person or company who conducts a ship's business in a port on behalf of the shipowners or charterers.

Some oil rigs or offshore vessels utilize a series of pipelines to deliver the oil to the refinery on shore while others may use a shuttle tanker. This vessel is equipped with off-loading equipment that is compatible with the oil field, rig or vessel that it works with.

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

Sierra stands for the letter S 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.

The signal lamp (also called an Aldis lamp or Morse lamp) is a hand-held electric lamp which is normally found on the bridge wing of a vessel. It is used to signal Morse code messages via flashing light between ships of all types, including naval and commercial.

The signal lights on a boat or ship help the navigating officers onboard determine which vessel should give way to another when they encounter each other at night. Navigation lights must be displayed from sunset to sunrise as well as during the day if there is poor or limited visibility, such as in overcast weather or fog. These lights are also referred to as navigation lights, or marine navigation lights.

Otherwise known as a SPAR platform, Single Point Anchor Reservoir Platforms are floating oil platforms that provide a more stable alternative to conventional platforms. They are typically used in ultra deep water.

Their design consists of one or more large, vertical buoyant cylinders which support the deck. Single Point Anchor Reservoir Platforms are permanently anchored to the seabed by solid cable lines. 

A sister ship is a vessel that has been built to the same design as another.

Slave clocks, also known as secondary clocks, are the timepieces that are located throughout a vessel. It is crucial that they all display the exact same time and this is ensured by having them controlled by a master clock - also known as a main clock - which transmits signals or control pulses to the slave clocks that are connected to it.

The slop chest on a ship refers to personal items that the crew can purchase while they’re onboard. This includes anything from clothing and boots to food such as instant noodles and candy to sim cards and beer, if it is allowed on that vessel.

A record of purchases are kept for each seafarer and payment is usually taken from their salary at the end of the voyage. The name comes from "slop" which was once slang for the cheap clothing that a rating (a skilled seafarer who works in a support role on a ship) in the navy could buy. The chest was, of course, the chest in which this clothing was stored.

SMCP stands for Standard Marine Communication Phrases and is the name given to the language seafarers use at sea. It combines the English language with specific maritime terms and commands (for example, starboard instead of right or aft, meaning towards the rear of the vessel). It is used so that seafarers of different native languages can communicate with one another safely and efficiently. A certain level of proficiency in the English language is required by most reputable shipping companies. SMCP is also known as Maritime English and Seaspeak.

SOLAS stands for Safety of Life at Sea Convention. An international treaty that specifies minimum standards for the construction, equipment and operation of ships, compatible with their safety. The first version of the convention was adopted by the IMO in 1914 as a response to the sinking of the Titanic. 

Sonar on a boat or ship is an instrument that is used to ascertain how deep the water is under the vessel’s keel. It does this by transmitting pulses of sound which bounce - or echo - off the sea bed, similar to the way an echo sounder works.

The difference between an echo sounder and sonar, however, is that echo sounders transmit their pulse vertically while sonar transmits its pulse horizontally. There are two types of echo sounder: the single beam echo-sounder and the multi beam echo-sounder. 

Short for Single Point Anchor Reservoir Platform, in shipping terms, SPARs are floating oil platforms that provide a more stable alternative to conventional platforms. They are typically used in ultra deep water.

Their design consists of one or more large, vertical buoyant cylinders which support the deck. SPARs are permanently anchored to the seabed by solid cable lines. 

In maritime terminology, a speed log, also sometimes referred to as a ship log, common log or chip log, is an instrument which is used to measure a ship’s speed and the distance it has traveled. The speed is determined by referencing the water flowing past the hull (water reference speed) or by the seabed (ground reference speed).

There are five different types of speed log which all work on different principles: the electromagnetic speed log, the pitometer speed log, the doppler speed log, the impeller speed log and the satellite speed log. See their individual glossary entries for more information on each.

A spreader is a piece of equipment that lifts shipping containers by their corner posts. The spreader bar on a container crane is telescopic and enables the crane to lift containers of different lengths.

Standard Marine Communication Phrases (SMCP) is the name given to the language seafarers use at sea. It combines English language with specific maritime terms and commands (for example, starboard instead of right or aft, meaning towards the rear of the vessel). It is used so that seafarers of different native languages can communicate with one another safely and efficiently. A certain level of proficiency in the English language is required by most reputable shipping companies. Standard Marine Communication Phrases is also known as Maritime English and Seaspeak.

This refers to the right hand side of a vessel facing forwards. At night the starboard side of a ship is identified by a green light.

 A steamship, also referred to as a steamer, is a type of steam-powered vessel. Steamship is usually abbreviated to SS and used in front of a vessel’s name. For example, the SS Great Eastern.

Ships of all sizes are steered by a rudder, but the rudder’s movements are reliant on a system called the steering gear. This gear enables the rudder to turn, and therefore so too, the vessel, both at sea / when sailing, or when maneuvering. . Standard requirements decree that the steering gear should be capable of steering the ship from 35 degrees port to 35 degrees starboard, and vice versa, while the vessel is moving forwards at a steady rate of knots. 

Generally speaking there are two types of commonly-used steering gear systems: hydraulic steering gear systems and electro-hydraulic steering gear systems.  Consisting of three main components including a power unit, a control unit and transmission to the rudder stock, both transmit a torsional force to the rudder stock - the equipment that operates the rudder. 

Steering gears only work when the vessel is in motion and not when stationary.

The stern is the bow or rear of a ship.

Stern thrusters are propellers on the stern 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 stern sideways in whichever direction they are employed and are usually used when mooring or docking.   

The stern tube is a hollow tube which houses the bearings, seal boxes and propeller shaft on a ship. It enables the tail shaft to smoothly rotate in the bearing area so that the vessel can enjoy uninterrupted propulsion. The stern tube also creates a barrier between the sea water and the ship’s engine room and is filled with water, oil or grease to keep it lubricated.

Sternway is the word used to describe the action of a vessel moving backwards.

Also called a dock worker or Longshoreman, a Stevedore is a land-based maritime job which involves loading and unloading cargo from vessels in ports. They also undertake administrative tasks relevant to this work.

A ship’s Steward will most often be found working on a cruise ship, a mega yacht or a superyacht. Their main tasks are to help prepare and serve meals to guests and take care of housekeeping. However they may find themselves doing anything from creating flower arrangements to acting as a personal assistant to an important passenger. They report directly to the Chief Steward or Chief Stewardess.

In maritime terms, a ship’s Stewardess will most often be found working on a cruise ship, a mega yacht or a superyacht. Their main tasks are to help prepare and serve meals to guests and take care of housekeeping. However they may find themselves doing anything from creating flower arrangements to acting as a personal assistant to an important passenger. They report directly to the Chief Steward or Chief Stewardess.

Stowage has a few different meanings, all related to the act of storing an item on a ship - i.e. stowing it. It can refer to the act of putting goods out of harm’s way to ensure the stability and safety of the vessel. It is also the space for stowing something in, and the amount of room available for stowing items. On a container ship, stowage refers to the arrangement of the containers on board.

A straddle carrier is a piece of motorized equipment located at a container terminal. The straddle carrier runs on rubber tires and can straddle a single row of containers. It’s mostly used to move shipping containers around the terminal, but may also be used to transport containers to and from the transtainer and load and unload containers from a truck chassis.

Also commonly referred to a grounding or running aground, as in when a ship hits the bottom, the main difference between a grounding and a stranding is that in maritime terminology, stranding refers to when the vessel then remains stuck in position for a length of time.

Stripping is a freight term and is the act of removing cargo from a shipping container.

Stuffing is the act of packing a shipping container with loose cargo.

Suezmax is a measurement term that refers to the maximum vessel size that is able to transit the Suez Canal. The term is used almost exclusively in reference to tankers.

A Suezmax tanker can typically carry 125,000 to 199,999 DWT. It is the maximum tanker size that is able to transit the Suez Canal.

A Superyacht is an, often very luxurious, vessel which is used for pleasure. There is no real standard definitive length but generally, to be considered ‘super’ a yacht will measure a minimum of 24 meters (78 feet).

A Supramax bulk carrier is a class of vessels that are used for the transport of unpacked and loose goods. They have a cargo capacity of 50,000 to 60,999 DWT and are often also referred to as a Supramax vessel or Supramax bulker.

A Supramax vessel is a class of bulk cargo carriers that are used for the transport of unpacked and loose goods. They have a cargo capacity of 50,000 to 60,999 DWT and are often also referred to as a Supramax bulk carrier or Supramax bulker.

A survival craft is a boat (or raft) which has the ability to sustain the lives of the crew or passengers in the event that they need to abandon ship. Survival crafts are generally lifeboats and liferafts, but not rescue boats which are used in all and any emergencies including man overboard situations.

A survival suit, also referred to as an immersion suit, falls under the personal life saving appliances category and is a waterproof all-in-one garment that provides the wearer with protection against hypothermia when they are in cold water or otherwise exposed. Survival suits are most commonly used after abandoning ship, particularly when in open seas.