Glossary

These definitions, provided for readers not familiar with nautical terms, are those used for purposes of the present study. Some definitions may not be applicable in other contexts.


ballast:

non-cargo load (generally sea water) used to make a vessel without cargo heavier and more stable.

barge:

a tank vessel lacking onboard means of propulsion.

bending moment:

the summation of forces (ship and cargo weight, buoyancy, and dynamic) acting on a vessel's hull that tend to bend the hull.

bulkhead:

longitudinal or transverse structure dividing cargo tanks.


class:

classification society.

combination carrier:

a vessel designed and built to carry dry, bulk, or liquid cargo.

crude oil washing (COW):

a method of washing or rinsing out cargo tanks, using high-pressure jets of crude oil as the washing medium.


deadweight:

a measure of the carrying capacity of a vessel (the weight of cargo, fuel, fresh water, and stores).

draft:

the depth of water a vessel draws, especially when loaded.

DWT:

deadweight tons.


Exclusive Economic Zone:

area generally considered to extend 200 nautical miles from shore.



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OCR for page 335
Tanker Spills: Prevention by Design Glossary These definitions, provided for readers not familiar with nautical terms, are those used for purposes of the present study. Some definitions may not be applicable in other contexts. ballast: non-cargo load (generally sea water) used to make a vessel without cargo heavier and more stable. barge: a tank vessel lacking onboard means of propulsion. bending moment: the summation of forces (ship and cargo weight, buoyancy, and dynamic) acting on a vessel's hull that tend to bend the hull. bulkhead: longitudinal or transverse structure dividing cargo tanks. class: classification society. combination carrier: a vessel designed and built to carry dry, bulk, or liquid cargo. crude oil washing (COW): a method of washing or rinsing out cargo tanks, using high-pressure jets of crude oil as the washing medium. deadweight: a measure of the carrying capacity of a vessel (the weight of cargo, fuel, fresh water, and stores). draft: the depth of water a vessel draws, especially when loaded. DWT: deadweight tons. Exclusive Economic Zone: area generally considered to extend 200 nautical miles from shore.

OCR for page 335
Tanker Spills: Prevention by Design flag of convenience: flag state selected (by non-resident shipowners) on the basis of favorable conditions for non-residents in terms of commercial flexibility and tax treatment. flag state: a nation where ships can be registered. freeboard: the distance from the waterline to a vessel's deck. free surface effect: cargo movement resulting from light loading of tanks that tends to reduce vessel stability. girders: large structural support framing in tanker hull. Girders can be transverse or longitudinal, and vertical or horizontal. green water: heavy seas washed on deck. gross registered tonnage (GRT): a volumetric measure of both earning spaces (for cargo) and non-earning spaces, such as the engine room, bridge, and accommodations. heel: the extent of a vessel's incline or tilt to one side. hydrostatic balance: the level of oil in a cargo tank such that the oil pressure is equal to the exterior sea water pressure. IGS: inert gas system (a safety feature that prevents combustion by using non-flammable, or "inert", gas to exclude oxygen from tanks). IMO: International Maritime Organization, the United Nations agency responsible for maritime safety and environmental protection of the seas. lightening: same as lightering. lightering: the process of transferring cargo at sea, from one vessel to another. lightweight: weight of a ship without cargo, crew, fuel, or stores (same as lightship weight). list: a ship's tilt to one side in a state of equilibrium (as from unbalanced loading). load on top (LOT): a cargo loading system that minimizes operational pollution: when oil and water are left standing, the heavier water sinks and can be drawn off and returned to the sea, and cargo "loaded on top" of remaining oil/water residues. LOOP: Louisiana OffShore Oil Port (18 miles off the coast of Louisiana in the U.S. Gulf of Mexico). MARPOL: The International Convention for the Prevention of Pollution from Ships, adopted in 1973 and amended in 1978. It constitutes the basic international law for limiting all ship-source pollution, including structural and operational provisions for tank vessel pollution control; the term is used in this study to describe the current standard for vessel design.

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Tanker Spills: Prevention by Design net registered tonnage: a measure of the earning capacity of a vessel, based on cubic capacity of revenue-earning spaces. ocean-going: a vessel designed and certificated (authorized by the U.S. Coast Guard) for operation on ocean routes but not on inland (except for port entrances) or Great Lakes waters. In the present study, the term refers to vessels over 10,000 DWT. peak tanks: tanks at the bow and stern, often used for ballast. PL: a MARPOL provision for protectively located ballast tanks (refers to strategic placement of SBT, to afford some protection in a grounding or collision). retrofit: major structural alteration of an existing vessel. SBT: segregated ballast tanks (tanks dedicated to carriage of seawater ballast, never cargo). For purposes of this study, refers to MARPOL requirements for SBT. scantlings: the dimensions of the structural members of a vessel. SOLAS: the international convention for the Safety of Life at Sea. It constitutes the basic international law governing ship safety features for ships and their crew. tanker: a tank vessel with onboard means of propulsion. territorial waters: each flag state may establish its territorial waters up to 12 nautical miles from baselines (determined in accordance with the 1982 Law of the Sea Convention). transshipment: re-shipment of crude oil or petroleum products. trim: the position of a vessel with reference to the horizontal, or the difference in draft forward and aft. ullage: the space in a cargo tank above the cargo. VLCC: Very Large Crude Carrier (can refer to vessels over 160,000 DWT or 200,000 DWT). webs: structural support framing in tanker hull (see girders).

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