Tail shaft: the extreme section at the aft end of a ship's propeller shaft.

Tank barge: a river barge designed for the carriage of liquid bulk cargoes.

Tank cleaning: removal of all traces of a cargo from the tanks of a tanker normally by means of high pressure water jets. 

Tanker: a tanker is a bulk carrier designed to transport liquid cargo, most often petroleum products. Oil tankers vary in size from small coastal vessels of 1,500 tons deadweight, through medium-sized ship of 60,000 tons, to the giant vlccs (very large crude carriers).

Tender: the offer of goods for transportation.

Territorial waters: that portion of the sea up to a limited instance which is immediately adjacent to the shores of any country and over which the sovereignty and exclusive jurisdiction of that country extend.

Third assistant engineer: in charge of eight to twelve watch and maintains lighting fixtures; repairs malfunctioning accessories in living quarters and assists other engineers as directed.

Third mate: in charge of eight to twelve watch. This person makes sure emergency survival equipment (lifeboats, life rings, etc.) Are in order and will assist other officers as directed.

TI: transportation institute.

Time charter: a form of charter party wherein owner lets or leases his vessel and crew to the charterer for a stipulated period of time. The charterer pays for the bunkers and port charges in addition to the charter hire.

Title XI: a ship financing guarantee program.

Ton mile: a measurement used in the economics of transportation to designate one ton being moved one mile. This is useful to the shipper because it includes the distance to move a commodity in the calculation.

Tonnage: deadweight, gross, net, displacement; a quantity of cargo normally expressed as a number of tons. 

Top-off: this means to fill a ship which is already partly loaded with cargo.

Tow: when one or more vessels are being towed; when a tug is towing one or more floating objects; to pull an object in the water by means of a rope.

Towage: charges for the services of tugs assisting a ship or other vessels in ports or other locations; the act of towing a ship or other objects from one place to another.

Tramp service: vessels operating without a fixed itinerary or schedule or charter contract. 

Transship: to transfer goods from one transportation line to another or from one ship to another. 

Trim: the relationship between a ship's draughts forward and aft.

TSA: transportation security administration. 

TSAC: towing safety advisory committee, an industry advisory body to the u.s. coast guard. 

Tug: a small vessel designed to tow or push large ships or barges. Tugs have powerful diesel engines and are essential to docks and ports to maneuver large ships into their berths. Pusher tugs are also used to push enormous trains of barges on the rivers and inland waterways of the u.s. oceangoing salvage tugs provide assistance to ships in distress and engage in such work as towing drilling rigs and oil production platforms.