The position onboard, second after the Master, takes the command of the ship in case the Master is incapable ( for instance sick ). Supervises the work of the other deck officers and the deck crew, also responsible for cargo operations.

A seaman / sailor in charge of ship's ( life ) boat and usually it's helmsman. Not any more in common use on modern cargo ships. Also the person who steers a racing shell and calls out the rowing rhythm for the rowing crew.

The total weight of the volume of water the ship displaces when immersed to full cargo loading capacity. Includes everything onboard, also the weight of the ship itself.

Dynamic Positioning and Dynamic Positioning Operator. This is a computerized ship control system, using forward and stern thrusters ( propellers ) in combination with ship's main engine and rudder to remain in a constant position, regardless of wind and/or current. Mostly used during offshore operations when necessary for ship to stay within a few metres of an installation without touching it. The system can be controlled through an "joystick"

European ( Union ) Maritime Safety Agency. In the European Union this organization have the same function as country specific coast guard agencies, for instance US Coast Guard.

Seamen's medical fitness certificate issued by an authorised doctor. ENG1 is commonly used as an abbreviation because it's the name of the form used in Britain for a seafarer that's fit for duty in his/her chosen job position.

Electronic Position Indicating Radar Beacon. All ships subject to the International SOLAS convention must have this ( ships in foreign ocean-going trade ). There are a minimum of 2 beacons onboard, one at each side - usually on each bridge wing. If the ship sinks they float free and when coming in contact with seawater they will directly activate. The radar signal can be seen on a regular ship's radar.

"Floating, Storage, and Offloading" and "Floating, Production, Storage, and Offloading". Can be an old big tanker where a small refinery has been added on deck. Used as offshore storage with direct offloading to smaller shuttle tankers that take the oil to a shore terminal. FPSS is a "Floating Production Semi-Submersible".

"Floating, Storage, Regasification Unit" Used as offshore storage of LNG gas with direct offloading to smaller shuttle tankers that take the oil to a shore terminal.

Global Maritime Distress Signal System. International Satellite based ( INMARSAT ) Maritime Safety and Security Information System. This has also replaced former morse radio signal based communications at sea. The operator ( usually a deck officer ) must have a "GMDSS" certificate issued by a Maritime Authority. - ISPS Summary

Gross Tonnage ( GT, gt ) is a unitless index of a ship's total enclosed volume. It's different from Register Ton ( see below ) and came into force in 1982, replacing GRT. The formula for calculating this is given in Wikipedia.

200 grt equals about 500 GT; 1,600 grt equals about 3.000 GT - Source.

Gross Register Ton or Net Register Ton is a volume measurement ( 100 cubic feet = 1 ton ) of the ship's cargo carrying space. It was often used by port and canal authorities as a basis for charges ( fees ). Gross tonnage formed the basis for manning regulations, safety rules, and registration fees. Also used as a capacity measurement for passenger ships and for instance car carriers ( Ro-Ro ) where the weight of the cargo is very small compared to the ship's own weight. It was in 1982 replaced by Gross Tonnage ( GT ), see above.
- Gross = all enclosed space onboard ( according to calculation rules ).
- Net = all enclosed cargo space onboard.

Already before year 200 B.C. in early Roman times the ( Roman ) cubic feet was used as a ship cargo measurement. One Roman cubic feet was contained in one amphora, which was a clay "bottle" for carrying grain / wheat. Equals about 25 litres ( 6 US Gallons ) or about three percent less than a modern cubic feet. Same ship cargo measurement has therefore been in continuous use for well over 2.000 years.

Oil rig often of a triangular shape with one "leg" in each corner. The legs are operated either hydraulically or electro-hydraulically. When the rig has been towed into the desired position the legs are sank to the sea bottom, after which the rig "lifts itself" above the sea level.

Knot is the unit for indicating the speed through water of a boat or a ship ( or any floating vessel ). One knot means one nautical mile per hour.

During earlier times on the sailing ships, the ship's speed through the water was measured in the following way. Usually the bosun together with an assistant went to the forward most part of the deck. The assistant had an "hour-glass" measuring a short time, for instance 10 or 20 seconds. The Bosun had a rope with a piece of wood attached to the end. At regular intervals the rope had a knot tied on the rope, starting at a point where the piece of wood would touch the water. At same time as the Bosun threw the piece of wood overboard and let the rope run out through his hand, his assistant turned over the hour-glass. When the time run out he told Bosun, who fastened his hand on the rope. If his hand was, for instance, between the sixth and the seventh knot, the ship's speed at the moment was 6.5 knots or 6.5 nautical miles per hour.

Knots per hour therefore means acceleration or deceleration. If you say "we were doing 6 knots per hour" it would mean the ship's speed accelerated ( increased ) by 6 nautical miles per hour every hour.

Long Range Identification and Tracking, goes with AIS (which see), for tracking ships by satellite, for instance, in connection with terrorist hijacking - ISPS Summary.

One nautical mile is one 60^th of one degree of arc latitude ( i.e. one minute of arc ) and equals 1,000 fathoms or 6,000 feet or 1,852 metres.

Non-Destructive Testing - A quality control inspection method. For instance using X-ray or ultrasound for checking / testing a welding seam without any effect on neither the seam itself nor the surrounding area. This can also be done under water.

National Examination Board in Occupational Safety and Health - UK