Tankers transport oil, chemical products and liquids gas. Oil tankers transport liquid products such as crude oil, refined petroleum products such as gasoline and chemical solutions. An oil tanker is a typical example of a ship of this class, which can transport crude oil in bulk and carries oil that supports the demands of human life and economic demands. As a rule, a crude oil tanker, such as a very large carrier, weighing more than 200,000-320,000 tons, is used for such cargo transfer. Different cargo tanks inside ships allow different types of crude oil to be transported. Ships are large and complex systems and are often part of some even larger and more complex transport systems under uncertain environmental influences and service requirements. They consist of several subsystems, each of which is important for the operation of the whole. Tankers are present in all seas today, and the first appeared in the late 19th century. They are most commonly built to transport crude oil or its derivatives, but there are also tankers for other types of liquid cargo such as chemicals and liquefied gas that perform transfers of these cargoes around the world. Various conventions and rules have been adopted to protect people as well as the ecology of the world in order to better preserve the world. Maneuvers with unloading and loading of cargo are very complex for each individual type of ship and due to the differences of cargo and very different. The construction of tanker construction changed over time as did the design characteristics of tankers. Various system technologies have been introduced for the best and most efficient way of doing work. Unloading cargo and washing tanks with crude oil are the most risky operations on oil tankers, where there is a need for careful planning of operations, and coordination of operations with the port terminal where the cargo is unloaded. Effective communication and efficient preparation are the key to safe and fast unloading of cargo