Considering sea freight transportations, it is useful to know what ships are designed for transporting certain products and how their characteristics contribute to maximizing the benefits for the client.
From the general classification, the following most common types of sea freight transportations are being distinguished.
Container ships are designed to carry cargo packed into standard ISO containers. The length of container ships varies from 80 to 400 m, deadweight tonnage - 8 to 20 thousand tons, capacity - 250 to 18 thousand containers. Such ships are fitted with a high degree of automation, the manning requirement can fall to 10-14 people.
The hold of a container ship is equipped by vertical beams that facilitate loading of containers (containers are stacked one on top of another) and prevents their shifting during ship’s movements at sea. After containers are loaded into holds, they are loaded onto decks where they are secured by special equipment: lashing bars, chains, turnbuckles.
Loading and unloading processes are ten times faster than with general-purpose bulk carriers, since the holds are loaded with standard cargo containers instead of individual pieces of various sizes and tonnage. The discharging of such vessel is done with the use of port cargo handling equipment – gantry crane with a maximum lifting capacity of 25 tons.
A bulker (bulk carrier) is a ship designed to transport unpacked bulk cargo, such as coal, building materials, grains, sand, crushed stone, ore. Bulkers are constructed with a single deck and are characterized by a high deadweight tonnage (around 150 thousand tons) and slow speed. The holds have angled walls (upper and lower part) for sorting dry bulk cargo. The majority of such ships don’t have loading equipment, so the machinery available on the dock is used. Some bulkers are equipped with conveyor belts for unloading cargo from holds, so-called self-discharging ships.
Another common type of vessels used in sea freight transportations. They transport liquid foods (such as wine and vegetable oil), oil and petroleum products, and natural gas. Tankers account for almost half of all sea freight transportations.
Despite the fact that sea freight transportations are very time-consuming, they are suitable for transportation of perishable goods. Fish, meat and dairy products, fruits and vegetables can be transported on reefer ships, equipped with refrigerators. Due to the maintained temperature regime inside, cargo will not spoil during the transportation.
RORO ships are cargo vessels which have horizontal loading of wheelbase vehicles through stern ramps – trucks and passenger car, r/r wagons, etc. Cars can drive directly onto the ship or can be loaded with the use of port cranes with a maximum lifting capacity of 30 tons. Deadweight tonnage of such ships is 1 to 10 thousand tons. One of the main advantages of RORO ships is the high speed of loading/unloading. The hull of a RORO ship is loaded with wheeled cargo, and the deck is used for carrying 20’ and 40’ containers. RORO ships are essentially ferries, only freight ones.
Timber carriers are used for transporting timber (round and sawn wood), as a rule, with a single deck. They are reinforced with icebreaker bows which allow them to enter ports around the Arctic Ocean.
It is worth mentioning that nowadays cargo ships have a deadweight tonnage over 500 thousand tons, and their technical equipment allows not to be afraid of the wind sea, which makes sea freight transportations most convenient and safe.