TYPE OF SHIPS FOR SHIPPING ACTIVITIES

General-cargo ships - Once the most popular type, nowadays general-cargo ships are still built but in small quantities. Their carrying capacity is 4,000-6,000 t on average and may reach 16,000 - 20,000 t. General cargo includes items which are packed (boxes, barrels, bags, packages) or not packed (pipes, bricks, machinery, rolls of wire). Refrigerator chambers to keep perishable foods, tanks for carrying vegetable oils and air-conditioned systems for furs needing special care are being provided on modern vessels. However, the disadvantage is that loading and unloading takes a long time which causes delay. Ships for general cargo may sail on a fixed route (that is, making regular voyages between two ports) or may supply cargo wherever merchants want them to.

Specialized ships - Its based on the cargo is carefully distributed according to its type and requirement of special conditions and need special handling requirement provided by the ships.

Reefer - they transport perishable foods such as fruit, vegetables, meat, fish and dairy, having a carrying capacity of 8,000 - 12,000 t. T Foodstuffs are kept in holds with good heat and freezing insulation at a temperature varying from -25 C to +13 C depending on the type of cargo. Reefers are equipped to carry not only frozen stuff but also goods which first have to be refrigerated to a specific temperature for transportation.


Timber carriers - one-decked ships designed to carry logs and beams; carrying capacity - 5,000 - 20,000 t, speed - 13-15 knots.

Containerships - carrying capacity - 8,000-15,000 t on average and 25,000-30,000 t for big containerships;

These ships are classified as unit-load ships because freight is carried in huge boxes of standard size (units), usually from 10 to 40 t. 

Actually these are the same we see on trains and trucks proving one of the advantages of containerships and those boxes: the delivery can be transported to the recipient using the link wagon - car - ship with least damage of cargo.
The higher speed (of 20-26 knots) and shorter port stay are a few of their advantages over other types of ships. The boxes, also called containers, may carry anything - fruit and meat (in special refrigerator containers), chemicals and acids, textile, instruments and metals, TV sets, radios and computers, even cars and ships! 

Due to this peculiar ship design and method of units, loading and unloading is done much faster.
Records for the fastest work have been set, the recent one being an unloading of 104 containers per hour (Hong Kong, 1982). Usually loading procedures are performed with cranes ashore at special places called "terminals" but smaller containerships have their own cargo-handling gear.

Barge-carrying ships (lighter ships) -This type of ships pertains to the category of containerships but the principle is slightly different. Cargo is carried in floating containers, also referred to as barges or lighters, each with a carrying capacity of 375 t - 1050 t. 

As these barges cannot sail on their own, they need to be tugged or towed to the ship. There, they can be loaded aboard in different ways depending on the type of lighter ship. For example, LASH (Lighter Aboard Ship) type has a high-capacity crane at the stern which lifts the barge, moves it horizontally over the deck and arranges it. SEA BEE type has a platform at the stern which is just like an elevator - it takes the lighter on and lifts it up to the deck. 

From then on, another device carries the barge to its place. The "integrator" lighter ship has its hull divided into sections so that the tug can move the barge straight into its compartment. 

Unloading is done in the same way on the following principle - lighters are unloaded from the ship, let in the water and tugged to the pier.
The advantage of this type of ships being that cargo can be carried in separate barges to and from smaller ports through a series of rivers and canals that are inaccessible for big ships.

Ro-ro ships - used for transporting motor vehicles and other wheeled equipment. Ro-ro is short for roll-on roll-off ships and is thus called because cargo is carried on wheeled containers or trailers. 

 Roughly speaking, their shape is "boxy". Ro-ro ships usually have 2-6 decks and look like huge parking lots with stern openings and lifting platforms to sort out trailers. Needless to say, loading and unloading is quite speedy. A common "representative" of ro-ro type is the car carrier (car-loading) which usually has cars directly loaded on the ship without putting them in containers. Modern car carriers are capable of carrying about 6,500 automobiles.

Bulk-carriers (bulkers) - designed to carry loose goods which constitute about 70% of all the shipments carried by sea; speed - 14 - 16 knots, carrying capacity - varies (there are ships with 30,000 t and others with 150,000 t);

 Bulk-carriers do not have cargo-handling gear aboard and have their goods loaded/unloaded by means of port devices. 

That's why all the space before the deckhouse is vacant to make load operations easier. There is an exception for some bulkers that work on a self-unloading principle.
Bulk cargo is a wide term. Heavy bulk-carriers usually transport ore , coal and coke, building materials, such as cement and gravel. Light bulkers carry grain, salt and sugar.

Unfortunately, goods such as ores and grain cannot simply be dumped in the hold of the ship without taking any precautions. Any careless maintenance of this cargo may result in damage of the ship. Just to give you an example - grain may ignite under particular conditions. 

Bulkers can also be all-purpose i.e. they may export bulk cargo and import oil or vehicles. This type tends to have many holds. An example of this type is the oil-ore carrier which may have a carrying capacity of 280,000t.

Heavy-cargo ships - designed to carry cranes, oil drills, machinery for factories and power stations, equipment for heavy industry and other cargo weighing 700-1000 t.