6. Types of cargo ships.

On one hand all cargo ships are divided into two types: dry cargo ships & tankers. On other hand, cargo ships may be divided into universal ships design to carry principal different types of cargo & specialized ships design to carry one type of cargo (e.g. bulk cargo, timber, refrigerated goods, oil etc.)

UNIVERSAL VESSELS. Universal vessels can carry practically any types of cargoes, including refrigerated & liquids (in special tanks). However, most of them are designed to carry certain types of goods. Thus, liners are intended to carry general cargo, packaged cargo, containers, & also, in dependence of the route, special, liquid & refrigerated cargoes. The modern tramp travels at between 12 & 15 knots. Its deadweight varies between 2.000 & 10.000 tons.

The cargo spaces are holds, tweendecks & deeptanks. Holds & tweendecks are used to carry general & bulk cargoes. Deep-tanks may be of two types. The first type is design to carry liquids only. The second type is design to carry liquid & dry cargoes in turn. Empty deeptanks are also used for liquid ballast.Typical universal standard design vessel is of 14.700 dwt (9.000 gross & 6.000 net tons). Her overall length is 450 feet, beam 69 feet, draught 31 feet. Her five holds are arranged so that numbers one to four holds are forward of the superstructure & only number five hold is abaft it.With a single diesel engine & screw she has a service speed of 14.5 knots, her fuel consumptions being around 22 tons per day. She provides accommodation for a crew of thirty.

MULTI-PURPOSE VESSELS.Nowadays universal vessels are gradually being transformed into multi-purpose vessels. Multi-purpose vessels, retaining versatility of universal vessels, that is their capability to carry different bulk & general cargoes, are becoming, to a certain extent, specialized. Thus, all multi-purpose vessels are adapted to carry standard containers. Some of them are adapted to carry rolled vehicles or heavy/bulky cargoes.

CONTAINER SHIPS.The cellular type full container ship is equipped to carry ctrs in the holds & on the hatch covers. Within the holds of the vessel there is a cellular structure of angle bars forming ctr guides into which the ctrs are stowed, on top of another. The ctrs carried on deck are carefully secured to ensure that they will not shift.

RO-RO VESSELS.Ro-Ro vessels are designed to carry all sorts of rolled vehicles & motor cars – by driving them to on/off the ship - & unitized cargo & lengthy/bulky cargo units. The type of access & distribution facilities are numerous, each designed to serve a specific purpose, such as: stern/bow doors & side ports, the doors being normally hydraulically operated; access ramps, internal ramps; hoistable platforms, lifts & bulkhead doors.

BULKERS.Bulkers are single-deck ships. The cargo is often shot straight into the hold & discharged by grabs, pneumatic suction plants & other bulk handling methods. The modern ocean-going bulk carrier dates fm the mid-fifties. Subsequent development has led to an increase in ship size, though not to the same extent as in tankers. There are bulk carriers of over 150.000 dwt today, but the largest of those in normal use are 60.000 & 70.000 dwt, known as Panamax size, while “handy size” bulkers are those in the 25.000-30.000-dwt range.

TANKERS.At present abt 1/3 of the word’s shipping tonnage is tanker tonnage. Tankers are especially designed to carry liquids in bulk. Their construction is entirely different fm that of dry cargo ships: they are built on a cellular system by which the vessel is divided longitudinally & transversely into compartments. Tankers are equipped with pipes, valves & pumps to transfer cargo fm/to the shore & fm one tank to another when necessary. They also vary in size, fm 2.000 dwt coasting tanker to supertankers of 70.000 dwt. They speed vary between 10 & 20 knots.