Marine / Sea Transportation

Marine transportation means moving people, goods, etc. by boat, ship and other vessels across oceans, seas, lakes, canals and rivers. This type of transportation for bulk and relatively heavy goods is cheaper than other methods, so the owners of goods and commercial companies carry out the largest volume of movement in this way. Iran, with more than 2,700 kilometers of coastal borders in the north and south, as well as its special geographical location, can act as one of the main sources of international transportation, especially sea transportation in the region.

Different types of cargo ships:

Liner ships (Regular lines)

The ships travel along specific sea routes according to predetermined criteria and schedules (Fixed and specific ports, ships, and freight rates). Liner companies are usually large and complex and have a presence in all ports where their ships travel. Network systems enable these organizations to support their customers by providing them with logistic services and detailed planning ensures continuous cargo supply for vessels. Through network systems, these organizations provide their customers with logistical services, and detailed planning ensures a vessel's continuous cargo supply.

Tramp ships (Irregular Lines)

Contrary to liner ships, tramp ships have no definite routes and schedules and deliver cargoes to any destination that clients specify. The voyages take place independently of one another in this mode. Good owners, who require frequent voyages between certain ports to transport a specific type of cargo, can rent these ships for up to six months or even a year or more. A charter party is an official contract between the ship owner and the one who rents it. The tramp companies typically have a small fleet of ships. There may only be one ship.

Different methods of sea transportation:

Cross Stuffing

Unloading the contents of a shipping line's container and loading it into another shipping line's container, in an intermediate country


Moving a container from one vessel to another that belongs to the same shipping line without unloading its contents


An agreement in which a ship-owner rents out his ship to a cargo owner to move cargoes from one point to another. (Suitable for transporting a large volume of goods or goods without special packaging


Getting individual shipments from different shippers combined, issuing a group bill of ladings, and delivering them to different consignees

Different types of cargo ships based on construction and purpose in International Transportation:

There are many types of ships. Here, we will introduce only those that are used in the field of international transportation.
Container Ships

For the transportation of containerized shipments

Bulk Carriers

Bulk carriers are divided into 4 categories according to loading capacity:

  • Handy Size carriers with the capacity of 10,000 to 35,000 tons
  • Handy Max carriers with the capacity of 35,000 to 50,000 tons
  • Pana Max carriers with the maximum tonnage capacity that can pass through the Panama Canal
  • Cape Size carriers, incapable of passing through the Panama Canal due to their very large size, that must pass through Cape Horn in the south of Chile in order to cross the Atlantic Ocean.

• Dry Bulk Carrier
For the transportation of goods such as grains (wheat, corn, soybean, …), cement, minerals, …
These carriers have hollow warehouses on their decks. Loading and unloading these carriers is done by bucket cranes. The capacity of these carriers varies between 10,000 and 360,000 tons. The height of the highest bulk carrier is about 340 meters.

  • Liquid Bulk Carrier

These carriers are similar to bulk carriers, but instead of large hatches on the tanks, they have small hatches that are used to inspect the tanks. Loading and unloading tankers is done with powerful pumps. For the installation of these pumps, a separate place other than the place of the tanks and the engine room has been considered.

These carriers are large or small. Small ones have many warehouses as they transport various types of petroleum products, while larger ones have fewer number of warehouses. Few people work in these carriers as mechanical devices are used to wash and clean the warehouses. These carriers are divided into three categories:

  • Oil Tankers: To carry oil and its derivation. These carriers are divided into 7 categories according to their capacity:
  • Handy Size: 10000 to 30000 Tons
  • Handy Max: 35000 to 50000 tons
  • Pana Max: 55000 to 75000 tons
  • Afra Max: 80000 to 115000 tons
  • Suez Max: 120000 to 150000 tons
  • VLCC (Very Large Crude Carrier): 200000 to 300000
  • ULCC (Ultra Large Crude Carrier): 300000 to 550000
  • Chemical Carrier

To carry liquid chemicals

  • Chemical Carrier

To carry liquid chemicals

Reefer Vessels

To carry food or perishable goods such as fruit, dairy products, proteins, etc. These vessels are equipped with refrigerators.

Roll on Roll off:

For moving wheeled vehicles; These ships have ramps, platforms and several different and movable floors.

Livestock Carriers

To carry live animals in large numbers; There is food, water, litter, medicine, etc. for livestock in these carriers. These journeys last from three days to three or four weeks.

General Cargo

To transport and store a wide range of goods in different forms such as barrels, bales, pallets, etc. in general; These carriers are usually equipped with cranes that can load and unload any type of goods. The hatch of these carriers are very strong and can withstand a large amount of cargo. Today, despite the high number of these types of carriers in the sea fleet, due to their low loading capacity on the one hand and the presence of container and bulk carriers on the other hand, they have lost their position.

LASH Ship—Lighter Aboard ship

These carriers are designed to carry other vessels, especially barges. They have cranes for loading and unloading barges. (A barge is a rectangular cube with a hollow space that usually does not have an engine or other propulsion and is pulled or pushed forward by a boat or other vessel on the water. The barge is used to transport goods to shallow docks and rivers.

Shipping speed

In the old days, the speed of a carrier or vessel was measured with a metric unit called a Knot (one knot is equal to 1.852 km), but today this speed is estimated by GPS, which is the most accurate known method and consists of three parts: transmitter, receiver and satellite system. Doppler shift is another method that is more expensive compared to GPS and uses the physical effect of Doppler in its operation. In this method the relative changes of the wave while moving are measured with the use of sonar devices. The average speed of different types of ships is as follows:

  • Bulk Carriers : 14 knots
  • Container ships : 20 knots
  • Oil tankers and its derivatives : 15 knots

Calculating sea transportation costs:

Sea transport advantages:

Recommended cargoes for sea transport:

Recommended destinations for sea transport:

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