Ship type of the three major transport ship ship type and performance analysis

One, the oil tanker

The oil tanker is used to transport crude oil, refined oil and other petroleum cargoes or other oil cargoes of the ship type. From the fleet structure, the representative ship type can be divided into five categories: ultra-large crude oil tankers, Suezmax, Aframax, Panamax, product tankers, chemical tankers.

Tanker by the cargo oil, their own weight, static water and ocean wave force, cargo oil shaking on the bulkhead of the impact of the combined load, as well as cargo oil on the structure of the corrosion and other roles, the structure must be more solid, but also must have enough fatigue resistance to the alternating load on the hull of the fatigue damage effect. Medium and large oil tankers, cargo oil area are used in the longitudinal structure, the bow and stern ends of the transverse structure, the engine room and cargo oil tank area are set double bottom. In addition to setting up longitudinal bone in side cabin, port side longitudinal truss is composed of truss frame structure, transverse in addition to setting up ordinary ribs, in the watertight transverse bulkheads, transverse frame is set up at certain spacing, in order to resist the impact of the cargo oil movement on the transverse bulkheads of the destruction of the cargo oil tanks set up a lightweight non-watertight system of the sloshing bulkheads. Longitudinal bulkheads are mostly flat bulkheads, and their reinforcement materials are placed in the side compartments, which is favorable for cabin cleaning; transverse bulkheads are mostly grooved bulkheads, and the lower end is connected with the wall piers to increase the load-bearing capacity. The arrangement of structural components and node connections, openings, pay close attention to the continuity and prevent stress concentration. In order to improve the longitudinal bending resistance and transverse shear capacity, many longitudinal and transverse members use high web truss structure.

For oil tankers, the loss and danger caused by marine accidents is much higher than that of bulk carriers and container ships, and the claim for marine pollution and the liability may be much higher than the value of the oil tanker itself. Tanker type in the development and evolution of the process, the cargo oil tank construction type appeared in the conventional type (single hull type), double bottom type and double hull type. Modern tankers are mostly double-hulled, generally with double shell, double bottom, single deck and several longitudinal bulkheads. Double shell space all arranged special ballast water tanks.

Two, container ship

1956 the first container ship came out, after more than 50 years of development, the container ship type after 6 generations of changes. 80's before the container ship for the small and medium-sized ship, the early 80's the emergence of the third generation of container ship is a high efficiency and energy saving type ship, . It increases the size of the hull, improve the transport efficiency, the loading number of container auxiliary reached 3000 TEU, load capacity of 20000 ~ 30000 tons, but the speed is reduced to 20 ~ 22 knots. The ship's scale is 240 to 275 meters in length. Less than 32 meters wide, draft 10.5 to 12 meters: cabin loaded with 9 to 10 Liu columns, 7-9 layers of containers: the deck can be loaded with 12 to 13 columns, 2 to 4 layers of containers. Since then the development of container ships is large, giant trend.

Contemporary large container ships can be divided into Panama-type ships, super Panama-type ships and ultra-large ships (VLCS) 3 categories. Recently, the Matouki company has taken the lead in the new generation of container ships "Emma Maersk", its ship size and box far more than the existing ultra-large ship, can be called "giant container ship" (ULCS). The ship to type width breakthrough 18 column box (45.6m) as the mark, and the most critical constraints on the technology is the propulsion system. At present, VLCS ship development to 10,000TEU type, single engine single propeller conventional propulsion has been played to the limit. To increase the size of the ship, there must be a change in the propulsion method, such as the use of double engines and double propellers, single engine + counter-rotating propellers (CRP) or a larger cylinder diameter, more cylinders of the single host. Maersk's new generation of "E" class ships were the first to break through 18 rows of box width, reaching 22 rows in one go. But its propulsion system is more special, not only for the first time using 14-cylinder main engine, but also another two power each up to 10,000kw power shaft system boost, by conventional generator sets and exhaust gas turbine generator to provide power.

Container ships in order to ensure high loading and unloading efficiency, the cargo hold opening is very large, the general width of the cargo hold opening for the ship's width of about 80%, and some even reach more than 89%. The strength of its hull longitudinal, transverse and torsional will be a problem that can not be ignored.

Three, bulk carriers

Currently the total capacity of bulk carriers in about 280 million tons. The current development trend is roughly ship type standardization, serialization, from the fleet structure, on behalf of the ship type can be divided into five categories, namely, 1 ~ 39,000t and 4 ~ 59,000t Handysize, 6 ~ 80,000t Panama-type, 10 ~ 190,000t Cape of Good Hope-type and more than 200,000t super-large bulk carriers. This kind of ships tend to shorten the length of the ship, the ship width and depth increase, the aspect ratio L / B decreased accordingly, handy type L / B about 5.5 ~ 5.8 between the hull of the short fat, but the load capacity and speed is increasing, and due to the Association of Classification Societies and other organizations on the hull safety issues are more and more attention to a variety of new requirements and rules continue to be introduced, the hull of the empty ship weight is also increasing.

The standard Panamax bulk carrier has a main scale configuration of 215 m×32.2m×12.5m, due to the limitation of navigable depth. Usually only get more than 60,000 tons of carrying capacity. In the Suez Canal navigation blocked period, in order to adapt to the long voyage, the demand for large capacity, excellent economy around the Cape of Good Hope of large bulk carriers have been developed, which is called the Cape of Good Hope type (Cape Size) of the bulk carrier usually has 10 ~ l 6 million tons of carrying capacity. In addition, there are ultra-large dedicated ore carriers, which can reach a scale of more than 200,000 tons. The newly proposed AFRAMAX ship type concept, that is, the comprehensive ship type economic argument weighing the best indicators of bulk carriers, breakthrough Panama Canal ship width restrictions, according to the capacity of most of the world's ports to accept bulk carriers to 45 feet as the upper limit of the ship's draught, through the increase in the way of increasing the width of the ship to increase the ship's carrying capacity. This type of vessel offers superior performance compared to the Panamax type and also allows for better economics.

Bulk carriers are different from other ships in terms of cargo type, loading condition and force deformation, which makes them more prone to "aging" than other types of ships and more likely to have accidents. Among them, bulk carriers with load capacity above 20000t and bulk solid heavy cargoes (e.g. ore) have the most sea damage accidents. The analysis of a large number of bulk carriers' sea loss accidents shows that under the adverse sea conditions, the damage of the structure causes the cargo hold to be flooded, which is the direct cause of the ship sinking accidents. Traditional single-hull bulk carriers on both sides of the single-hull outboard structure to deal with the cargo hold of the water defense line is essentially fragile, both sides of the hull steel plate in the collision stranding and torsion shear is most likely to rupture, resulting in the seawater back into the cargo hold, caused by the breakage of the stability of the cabin, the lack of anti-submergence, and ultimately lead to the sea loss accidents.

Therefore, the shipping and shipbuilding communities have proposed the adoption of a double-hulled (surface-flat cargo hold) bulk carrier concept that reduces the cost of heavy ship surveys and repairs and is inherently safer. The biggest advantage of a double-hulled bulk carrier over a single-hulled cargo of the same size is that even if cracks and holes occur somewhere on both sides of the hull of a double-hulled ship, the inner hull can withstand seawater backing up and prevent leakage of cargo from the holds, thus substantially improving the seagoing safety of the bulk carrier. However, the cost of double-hulled bulk carriers is higher than that of single-hulled bulk carriers, therefore, the preferred double-hulled bulk carriers that can better find this balance point will become the future development direction of bulk carriers.