_- 7 -_ _RoRo Vessels -_ Unit-load vessels where thU cargo is moved on and off using trailers normally carrying containers. A common characteristic of these vessels is their intermodal capability, which means that their cargo can go directly into the highway system.

- _Special Survey_ Every four years vessels must undergo a special survey of hull and another of machinery, although both may be postponed for up to a further twelve months if the classification society agrees, following a general examination which proves the vessel to be in a satisfactory condition. All sea-going vessels have to be maint ined in accordance with the rules and regulations of the class to which they were assigned.

- _Suezmax_ Referenced to vessels with certain dimensional limitations to be able to transit the Suez Canal.

_Tankers (Oil and Product) -_ These vessels are principally involved in the carriage of crude oil and its derivatives. The oil tanker category essentially comprises three types: (1) the Ultra Large Crude Carriers (ULCCs) which are used in long hauls; (2) the Very Large Crude Carriers which are used on the same routes as the ULCCs but with greater flexibilities in discharging port options, owing to their size; (3) the medium size Crude Carriers of 70,000 to 130,000 tons deadweight are mainly used on short hauls from Mediterranean, West African, Indonesian, and North Sea loading terminals to major nearby consuming areas. Product tankers with 26,000 to 40,000 tons deadweight are used primarily for the distribution of oil products from refinery to consumer.

_Tankers (Chemical,) -_ Class of vessel specifically designed to cater for the liquid chemicals market, capable of transporting various grades of chemicals, solvents, and acids in a variety of cargo compartments ranging from mild steel-lined, through tanks provided with different coatings, such as rubber-lined tanks for phosphoric acid.

_Tankers (Gas) -_ There are two categories: (1) Liquid Natural Gas (LNG) Tankers, and (2) Liquid Petroleum Gas (LPG) Tankers. The first category includes vessels designed to carry LNG, mostly methane, which is held in a liquid state by pressure and refrigeration. The cargo spaces consist of special tanks whose upper sections often protrude above deck height in domed or cylindrical form. The second category are vessels designed to carry LPG, such as butane or propane. These are also carried in special tanks under pressure and at very low temperatures. The tanks are often rectangular in section and may be flanked by wing tanks used to carry ballast water. The carrying capacity of both tanker categories is specified in cubic meters; typical tanker sizes range between 25,000 and 75,000 cubic meters.

_Time Charter -_ Under such contract a third party hires a ship for a fixed period of time. The shipowner is required to operate his ship but instead of freight payments he receives previously agreed sums of hire money, in advance and at regular intervals.

_Trip Charter -_ This type of chartering signifies a situation where a ship is hired for a single voyage or a roundtrip under which the owner maintains the responsibility for operating the vessel. But the rate of hire applicable to trip charters is generally more related to current spot market freight rates and not to the somewhat lower freight levels that are normally associated with time charters.

_Twenty-foot Equivalent Unit (TIEU) -_ The basic unit for expressing the capacity to carry containers on cellular, part-container, or RoRo vessels. The purpose of this unit is to have a common denominator for