Tankers are used for bulk transporting of crude oil, finished petroleum products, liquefied natural gas (LNG), chemicals, edible oils, wine, juice, molasses, fresh water, and other liquids. They play an important role in international trade with a share of over 33% of the world tonnage. Tankers come in varied sizes ranging from handysize tankers to ultra large crude carriers (ULCC) with a deadweight tonnage ranging between 320,000 to 550,000.

LNG carrier Mozah

History of Tankers

The first use of tankers in transporting bulk liquids dates back to the later years of the 19th century.  Before the advent of tankers, the idea of carrying bulk liquids in ships was considered a costly and even an infeasible affair. In that period, the market was also not ready for transporting or selling cargo in bulk. As a result, ships were used for transportation of a wide range of products in their holds. Liquids including wines and fresh water were usually loaded in casks.  With the discovery and exploration of oil, tankers have emerged as the main mode of transportation to carry crude and refined oil to ports across the world. Today, tankers carry over 33% of the world tonnage.

Juice carrier Carlos Fischer

Types of Tankers

Tankers can be classified on the basis of their cargo capacity as well as the type of product they transport.  On the basis of their purpose, they can be classified as oil tankers, chemical tankers, LNG carriers, Slurry tankers, Hydrogen tankers, Wine tankers, Juice Tankers and Integrated Tug Barges (ITB). Nowadays, supertankers like very large crude carriers (VLCC) and ultra large crude carriers (ULCC - deadweight tonnage of up to 550,000) are being built to carry huge amount of crude and refined fuels across the continents.  After pipelines, supertankers are the second best method for transporting huge quantity of oil in the world.
Product carrier Nord Inspiration

Classification of tankers by size

Aframax: Aframax are medium-sized crude tankers with a deadweight tonnage (DWT) ranging between 80,000 and 120,000. The tanker has a crude carrying capacity between 70,000 and 100,000 metric tonnes of crude. The average fuel carrying capacity of Aframax vessels is approximately 750,000 barrels. Due to their size, Aframax tankers are able to serve most ports in the world.

Panamax: Panamax are the mid-sized tankers that are capable of passing through the lock chambers of the Panama Canal. They have a deadweight tonnage between 50,000 to 80,000. These tankers are primarily used for carrying crude oil and petroleum products. 

Suezmax: Suezmax are medium to large-sized tankers with a deadweight tonnage (DWT) ranging between 120,000 to 200,000. They are the largest marine vessels that meet the restrictions of the Suez, and are capable of transiting the canal in a laden condition. A typical Suezmax tanker is 275 m (900 ft) long, 48 m (157 ft) wide, and 16.2 m (53 ft) in draught corresponding to about 150,000 DWT.

Very Large Crude Carriers (VLCC): VLCCs are large size tankers with deadweight tonnage ranging between 180,000 to 320,000. These tankers are capable of passing through the Suez Canal in Egypt, and as a result are used extensively around the North Sea, Mediterranean and West Africa. A VLCC can measure up to 1,540 ft (470 m) in length, up to 200 ft (60 m) in width, and has a draught of up to 66 ft (20 m).

Ultra Large Crude Carriers: ULCC or Ultra Large Crude Carriers are the largest tankers in the world with a size ranging between 320,000 to 550,000 DWT.  Due to their huge size, they require custom built terminals. As a result, they are able to serve limited number of ports in the world. They are primarily used for very long distance crude oil transportation, especially from the Persian Gulf to Europe, Asia and North America. Today, ULCC are among the largest shipping vessels with standard dimensions of 415 meters length, 63 meters width, and 35 meters draught. Knock Nevis was the longest ULCC supertanker ever built in the world with dimensions of 458.4 meters length and 68 meters in width.
ULCC Knock Newis