Glossary of maritime terminology

To tack, or tacking, in shipping terms, is the act of zig zagging a sailing boat through the wind so that it blows on opposite sides of the sails, firstly on one side and then on the other.

Tango stands for the letter T 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.

A tank barge is used for the inland transportation of liquids such as chemicals, petroleum, vegetable oils, liquefied gasses and even molasses.

In maritime terms, this is the act of thoroughly cleaning a tank to rid it of all traces of its former cargo. Tank cleaning is usually done using high-pressure water jets

A tanker is a bulk carrier that has been designed for the transportation of liquid cargo. Tankers may be oil tankers or chemical tankers and usually carry petroleum products. They vary hugely in size from small vessels that travel along coastlines to enormous VLCCs - Very Large Crude Carriers.

The Technical Manager is a company or person who is responsible for managing the crewing maintenance and insurance of a vessel.

The tension leg platform - often abbreviated to TLP - is a floating structure that is vertically moored to the seabed by steel tethers connected to driven piles. The tension leg platform is used both for oil and gas exploration and production.

Also sometimes called a wharf, in freight terms, the terminal is the place where cargo and shipping containers are handled. Vessels dock at the terminal to load and offload their cargo or containers.

The terminal operator is the company that handles activities related to cargo at a terminal. They supervise the unloading of cargo from the vessel to the dock, check the quantity of cargo is in line with what is listed on the manifest (list of cargo), check that all documents are in order, transfer the cargo into storage sheds, arrange for a logistics company to pick up cargo, and oversee the loading and unloading of railroad cars.

Twenty Foot Equivalent Unit (TEU) is used to describe the storage capacity of a container ship. A TEU is a unit of measure unique to the maritime industry. It is equal to the space taken by a twenty foot shipping container. For example, if a container is forty feet long, it measures two TEUs.

A thermal protective aid is a waterproof aluminized polyethylene garment with heat sealed seams. Shaped either like an all-in-one suit or something akin to a hooded sleeping bag, thermal protective aids are used to protect the wearer from the elements and help to prevent hypothermia, particularly when they are exposed to the elements in a lifeboat, life raft or rescue boat for an extended period. 

A through port deals with cargo that is not coming from, or intended for, the local market. Through ports are sometimes also called transit ports. It is more-or-less the opposite of a captive cargo port.

TLP is an abbreviation of tension leg platform. This is a floating structure that is vertically moored to the seabed by steel tethers connected to driven piles. The TLP is used both for oil and gas exploration and production.

Tonnage, in freight terms, can either mean the weight in tons of cargo or the size or carrying capacity of a vessel, measured in tons.

A toplift, in maritime terms, is similar to a forklift although it lifts shipping containers from above as opposed to from underneath. It moves containers at a terminal to and from storage stacks, railcars and trucks for onward transportation by land or sea.

The topping up air compressor on a ship is designed to deal with leakages in the system. Should a leak be identified, the compressor will cover it by stepping in and supplying pressurized air to the leaking system, thus replenishing it to its required level.

Towage can either refer to the charge for the service of a tugboat for assisting a vessel or the act of towing a ship or other objects from one point to another.

 A towboat, also called a pusher, pusher tug, or pusher boat, is a small but strong boat with a snub-nose shaped hull that is used to push barges in, out and around harbors. Smaller towboats are usually limited to pushing one or two barges, while larger boats (also known as a lone boat) can push anywhere from five barges up to forty.

In maritime terminology, a tramp is a vessel that operates on an ad-hoc basis and has no published schedule or fixed routes.

Transhipment is used to refer to the unloading of cargo at a port or other location where it is then reloaded, possibly into another mode of transportation, for transfer to its final destination.

A transit port deals with cargo that is not coming from, or intended for, the local market. Transit ports are sometimes also called through ports. It is more-or-less the opposite of a captive cargo port.

A transit shed is a shed on a wharf which is meant for short term use to protect cargo from the weather.

A transtainer is a type of large motorized crane that has rubber tires and can straddle up to six railway tracks. A transtainer can lift up to 35 tons and is used for loading and unloading shipping containers to and from railway cars.

A tugboat or tug is a small but strong boat with a V-shaped hull that is used to maneuver vessels in and out of ports. Large vessels such as container ships are too powerful to approach the dock under their own steam so they will cut their engines and allow the tug to pull and push them into position. Tugs are also used to carry supplies to other vessels.

The tween deck on a ship is a shipping term and is from shortening the word 'between.' Previously a space used to store precious cargo, on today’s vessels the tween deck is simply an empty space that is between two other decks on a ship.

Twenty Foot Equivalent Unit (TEU) is maritime terminology used to describe the storage capacity of a container ship. A TEU is a unit of measure unique to the maritime industry. It is equal to the space taken by a twenty foot shipping container. For example, if a container is forty feet long, it measures two TEUs.

A two-way radio telephone is a globally-used system of two way radio transceivers on ships and boats that is used for bidirectional voice communication. Also known as marine VHF radio or simply VHF radio, communication may be from ship-to-ship or ship-to-shore - for example a vessel communicating with the harbormaster or port authority.