Oil tanker ship

Out of the sheer need to transport “black gold” from remote areas of extraction to locations where they could be refined and become of significant importance, the creative ideas of an early oil miner found their feet and developed into a work of invention.

And a mighty marine masterpiece was born — the oil tanker ship.

An oil tanker ship is a large ship that moves oil across the globe. The size is dependent on the quantity of oil they carry and whether they travel through inland or coastal routes. With 2 million metric tons of oil each year, their importance in the oil industry cannot be overestimated.

Due to their colossal size, they offer a simple and cheap approach to transporting oil over long distances, providing a huge platform for big corporations to maximize their profit.

The advancement that was achieved by their emergence has never been relegated to the background. However, they‘ve caused serious issues too—the percentage of the most disastrous ecological calamities abounded because of their emergence on waterways cleaning equipment.

The first type of these ships was built in 1860s with wind-powered sail, which, subsequently, were replaced with steam engines. This was the ingenuity and product of the Palmer Shipbuilding and Iron Company, and was named Vaderland. Then, oil makers in Pennsylvania had their hands full with the utilization of badges; a large ship tugged by an alternate boat. They are usually unpowered.

Zoroaster was the name of the first oil tanker built and designed by Ludvig Nobel of Sweden in 1878. Ludvig and his sibling were at the helm of affairs at Branobel—a huge oil organization in the 1870s.

Oil tanker capacity

Oil tanker capacity is estimated based on their convey limit in dead weight (DWT), which is the total weight of a ship (including the load, crew, provisions, etc.) excluding the weight of the ship if unloaded.

Oil tanker capacities based on deadweight are as follows:


With an oil tanker size of 500,000 barrels, these tankers sure command a measure of respect in this industry. They are regarded as the largest vessel that travels through the Panama Canal.

A crude oil tanker of this sort weighs up to 70,000 dead weight tons (a crude oil tanker is one of the two types of oil tankers that move raw unrefined oil from where it is pumped out of the earth to where they will be refined).


Their weight ranges from 70,000 to 120,000 dead weight tons, with a capacity of 750,000 barrels of oil. In the Average Freight Rate Assessment tanker system (AFRA), they are the largest tankers. AFRA is a standard used for contract terms with well-defined ship capacity tanker explosion.


This is the largest tanker passing the Suez Canal with the range of deadweight tons from 120,000 to 200,000 and 1,000,000 barrels of oil.

Very large crude carrier (VLCC)

Their weight extends from 200,000 to 325,000 dead weight tons; used mainly in the Mediterranean Sea, the North Sea, and near West Africa, with an approximate capacity of 2,000,000 barrels of oil.

Ultra large crude carrier (ULCC)

It is also known as ULCC. The weight extends from 325,000 to 550,000 dead weight tons. Their capacity is up to 4,000,000 barrels of oil and they are used in the Persian Gulf to European and American to Asia.

Classification of tankers on the basis of their types

Oil tankers

They are tankers that convey oil and its by-products. The products also include petrol, gasoline, kerosene, paraffin.

The subdivisions of this category are as follows:

Product tankers: They’re used for transportation of petroleum-based chemicals

Crude tankers: They’re specifically used for transportation of crude oil from point of extraction to the point where it is refined.

LNG carrier

These ships are deployed for the transportation of LNG (Liquefied Natural Gas). Care and precautionary measures are taken due to the delicate nature of the materials they carry.

Oil chemical tanker

These tankers transport chemicals of various types. Their design allows for consistent maintenance. They are usually coated for ease of identification of chemicals to be transported.

Slurry tankers

Slurry is a word for the material that does not dissolve in water. They’re used as fertilizers and moved by these tankers to the areas of importance.

Hydrogen tankers

They find their importance in the transportation of liquefied hydrogen gas.

Juice tankers

These tankers are meant for carrying orange juice in mass quantities. Other fruit juice carriers are also available.


Transportation of wine these days can be done in sleek tankers of these types to the areas of intended use.

ITB (Integrated Tug Barges)

They are mainly used in the eastern coast of the US; basically, the tug and the barge are combined into a single cargo carrying unit.

As oil tankers ply the waterways, it has become imperative that their activities be put under control to ensure that safety procedures are absolutely complied with on board ships and at terminals. To this end, a safety guide meant to regulate the activities of vessels and terminals was published in 1978 and referred to as the International Safety Guide for Oil Tankers and Terminals (ISGOTT)

This guide provides operational advice to personnel involved in the activities of oil tankers and terminal operations. They include guidance, operational safety, better handling crude oil and petroleum products on tankers and at terminals.

ISGOTT is a combination of a petroleum tanker safety guide, international oil tanker safety guide, and terminal safety guide, published by the International Chamber of Shipping (ICS) and the Oil Companies International Marine Forum (OCIMF) respectively. Severally publications have been in the public domain since 1978.

This safety guide also extends to oil supertankers (VLCC) with capacities well over 250,000 DWT. These ships are capable of taking on 2,000,000 barrels of oil per 318,000 metric tons.


A barrel of oil

Questions such as “how many gallons make a barrel and how many barrels in a tanker?” will continue to generate so much fuss until things are put into perspective.

A barrel of oil is actually a unit of volume. In the US and Canada, one barrel contains 42 gallons of crude oil.

Today’s supertankers, on the average, can hold 2 million barrels or 84 million gallons of crude oil and petroleum products.

And according to the California Energy Commission, each crude oil barrel contains products such as:

  • Finished motor Gasoline (51.4%)
  • Jet fuel (12.3%)
  • Still gas (5.4%)
  • Distillate fuel oil (15.3%)
  • Marketable coke (5.0%)
  • Liquid refinery gas (2.8%)
  • Residual fuel oil (3.3%)
  • Asphalt and road oil (1.7%)
  • Lubricant (0.9%)
  • Other refined products (1.5%)

Oil tanker operational safety measures and general precautions

Oil tanker operation is a serious business in any part of the world and involves numerous complexities, and careful measures have to be taken into consideration to ensure safety on board.

They are as follows:

  • Restrictions on smoking, burning, and naked light activities on board of vessels.
  • Smoking prohibited in designated area when gas freeing and purging is in place
  • Hand gas lighters strictly prohibited but safety matches are allowed within the designated smoking area.
  • Permanent notices at entrance points and exits.
  • Strict control over the use of portable stoves and cooking appliances. Before their use, porthole and doors are closed and absence of hydrogen gas is confirmed.
  • At berth, gallery stoves are prohibited.
  • Electric heaters must be used at designated points only.
  • In areas, in which inflammable gas may be present, equipment like portable radios, electronic calculators are not used except for those of sealed-in type (for example tank volume calculator).
  • Personnel must be properly dressed when entering the cargo deck area and wear personal protective equipment.
  • Visitors on board are guided by notices at entrance points and allowed in upon presentation of ID.
  • Visitors are not allowed to access the cargo area or even the deck unless escorted by vessel personnel.
  • Combustible materials are stored in a well-ventilated area to avoid accumulation of inflammable gases—saw dust, oily rages, etc.


Oil tanker engine

Oil tanker engines are designed to power tankers carrying enormous amount of oil. For example, the largest oil tanker in the world—Jahre Viking, formally Seawise Giant,—with oil tanker dimensions measuring 1,504 feet (458.46m) as the oil tanker length; 266 feet as the width, and oil tanker weight of 564,650 DWT, carries up to 4,000,000 barrels of oil.

Tankers of this type are powered by very big engines, a typical example is the world’s biggest engine called Wartsila-sulzer RTA-96-c used to power super oil tankers and container ships, with dimensions measuring 89 feet long and 44 feet wide, and manufactured by Aioi Works in Japan.

The configurations of the cylinders are in these orders: 6, 8, 10, 12 feet and 2 inches. Each of the cylinders has a diameter of 3 feet 2 inches and a stroke of 8 feet and 2 inches.

The weight of the 12 cylinders is 2,000 metric tons with 90,000 horse power and a fuel economy of 53,244 HP at 100 Revs per minute.

This engine is regarded as the most powerful, and the fact that it operates at a slower rate, which is 20 times less than a 2.0 liter car engine makes it an added advantage to its life when at the middle of the sea with 100,000 tons of oil.

If the low speed is considered from the perspective of the power output, it’s a win-win situation when it comes to fuel consumption. The extraordinary fuel economy in the 14-cylinder type is too good to be true—it displaces 25,480 liters (1.56 million cubic inches burn only 1, 6660 gallons of crude oil per hour).

This colossal moving structure will continue to remain relevant in this industry, even if we use the chock full of opportunities it offers for years to come.

1 Star2 Stars3 Stars4 Stars5 Stars (4 votes, average: 4.00 out of 5)